Hi..I am Indrani Banerjee. I completed my bachelor's degree in mechanical engineering. I am an enthusiastic person and I am a person who is positive about every aspect of life. I like to read Books and listen to music.
In this given article we will briefly discuss about the topic of “Milling Machine Parts”. The milling machine parts are very useful and uses widely in the work of the production engineering.
In every milling machine tool in generally contain eleven parts.The parts which are carried by the milling machine tool is
The base is the part which is placed at the bottom of the milling machine tool. The whole parts of the machine tool are situated in the base.
The base is the foundation of the milling machine tool. The base should be enough rigid and the strength should be enough thus it could hold the whole machine tool.
Material used to make:
The body of the base made with cast iron.
Working Purpose:
1. To hold properly the machine parts of the milling machine tool.
2. Storage of the cutting fluid
3. To absorb the surroundings shocks.
Table:
Table is situated at the saddle’s top portion. The shape of the table is rectangular.
The table is control by the electric power in milling machine. But in common milling machine the milling machine is controlled by both man power and electric power and when the table is controlled by the manpower the hand crank is engaged longitudinally and when the table of the machine tool is controlled by the electric power that time control lever is engaged longitudinally.
Material used to make:
Table of the machine tool is made with cast iron.
Working Purpose:
1. The main purpose of the table is to grip the work piece and the work tool.
2. T slots are also placed in the table of the milling machine tool which are used to hold the work piece and work tool such as jigs and fixtures.
Arbor support:
In the milling machine the tool is support the arbor’s end portion with arbor support’s axle. The support of the arbor is pitch with the help of bearing.
In the milling machine tool general arbor support is categorized in two types. The one type is smaller diameter bearing which containing the hole diameter maximum up to 1 inch and the another one is bigger diameter bearing which containing the hole diameter is 5.75 inch.
Working Purpose:
1. The oil reservoir is placed in the arbor supports. Lubricate which is comes from the oil reservoir uses in the surface of the bearings.
2. In overhanging arm’s any places the arbor support can be clamped.
Knee:
The shape of the knee in the milling machine tool is almost looks like a human’s knee. The movement of the knee is vertically upon the face of the column. The knee can be moved upward and downward in the directions both.
Material used to make:
The knee of the milling machine tool is made with the help of grey cast iron.
Working Purpose:
1. Help to hold the feed mechanism which is situated in the table of the milling machine tool.
2. Also helps to grip the saddle.
3. By the help of the knee we could easily adjust the height of the column which is attached with the elevating screw.
Spindle:
The spindle is a machine tool which is act as an intermediate between the knee and table of the milling machine tool. The spindle is placed in the upper portion of the column.
It is actually a shaft which is work in the rotating motion. The spindle can be moved by both manpower and the electric power. The power of the machine tool such as gears, belt and clutches is received by the spindle.
Working Purpose:
1. To horizontally moves the workpiece.
2. The shaft of the spindle is act like as a supporter and positioned for the tool devices.
3. Support the column.
4. The spindle’s face is situated in the tapered machine of the table. The taper of the internal position is situated in the spindle’s face and only permits with arbor or the cutter which is in tapered.
Column:
The column of the milling machine tool is placed the vertical position of the base. The column is one of the most important part of the milling machine tool which carrying all the driving mechanism and also carry the motor.
In the column the v belt is used. The v belt is usually connected the motor and the driving mechanism. The driving mechanism is mainly used to control the speed. It is shaped like a box and all driving mechanisms are situated on it.
Material used to make:
Cast iron is used to make the column of the milling machine tool.
Working Purpose:
1. To hold the driving mechanism and motor.
Ram:
Ram can be defined as if the overhanging arm is present in the milling machine. The ram’s one ending part is attached with the column and other ending part is attached with the head of the milling machine tool.
By the help of the hand lever ram easily can be moved.
Motor:
The power is generated of the milling machine by the motor.
Head:
As the human body’s head the milling machine head is also situated at the top. The controlling mechanism is totally handle bf the milling head. The spindle and driven motor also placed in the head.
Machine tool:
The machine tool means the spindle carried the all the components by this the excess amount of material is removed to achieve the desired part.
Machine interface:
The meaning of the machine interface is the operator of the machine components used as machine program of the computer numerical control, load and initiate.
Saddle:
The saddle is placed in the knee and worked as a supporter of a table of the milling machine tool. The dovetail which is placed paralleled to the spindle’s axis. The saddle is present in the horizontal milling machine tool.
Working Purpose:
1. Guide the table with the help of the top portion of the saddle.
Front brace:
Front brace actually an additional support tool. By the help of the front brace the knee and overhanging arm get extra support.
Arbor:
The arbor of the milling machine meaning into the spindle when the component of the shaft is insert into the horizontal milling machine where tools of machine can be mounted. The component of the milling machine is in various sizes and diameters.
The arbor is present all most every milling machine that could be in end milling, normal milling machine, slitting saw milling cutter, screw, shell cutter arbors and milling cutter arbors.
Working Purpose:
1. Worked as the supporter of the cutters which are used in the milling machining tool.
2. Work tool can be easily hold and move by the arbor.
Milling machine:
In a production industry there a lots of machine and machine tools are present to do a wide range of operation in the work piece among them milling machine is one of the machine tool. By the help of the machine tool a wide range of cutting can be done in the work piece. A lots of operations which are in general very complicated to do on a work piece but with the help of the milling machine tool we can provide this complicated operation too. The operation we could easily do by the machine tool is,
Straddle milling
Indexing
End milling
Gang milling
Plain milling
Face milling
Side milling
Saw milling
Form milling
Angular milling or bevel milling
Spiral milling or helical milling
In industrial area the milling machine tool mainly used to produce the surfaces .The surfaces which are mainly in form of flat profiled. In other way the slots are made with the help of the tooth cutter which are revolving in multiple.
In the production engineering field there are different types of milling machine tools are present. The types of milling machine which are present in different form is named in the below section,
Solution: Jigs can be defined as the device which is helps to grip and locate workpiece of the milling machine tool and control the cutting tool that could be one or more than one.
In this article we will discuss about the topic of “Low Discharge Pressure” and also we will briefly discuss the others facts like types, causes, and how with the some several facts are directly related with the low discharge pressure.
Low discharge pressure can be defined as when the gases are discharges under the pressure of the gas in the range between some millitorr to very less than the atmospheric pressure. In the system if the pressure of suction side is increasing continuously then the phenomenon is increases inside the system.
The capacity of the compressor of the refrigeration system is decreases when the quantity of the inside temperature in increasing for some defects of the system. The benefit of the low discharge pressure is it’s required very less amount of power because the rate of the volume combination is less than the discharge substances.
The benefit of the low discharge superheat is the discharge is easily can be achieve uniformly .In the system only the plasma gas is flow in the plasma chamber when the air-conditioning system is pumped . The ionized gas present in the system is argon that is the big reason to break it very easily by chemically.
The phenomenon is of the air conditioning system can be easily resolve by following some steps. The coils in the refrigeration system carried dirt. When the dirt are mixed with the air which is flowing in the compressor’s suction line to the evaporator coils the temperature is increases and lower head pressure is appear inside the system.
The problem is mainly begins from the compressor of the refrigeration system. If we beginning of the process go through in the condition of the compressor and check the discharge valve of the compressor then the low discharge pressure can be avoided without any hassle.
Now the other process to control the low discharge valve into the refrigeration system is to check the inside condition of the valve of the evaporator. By the help of the evaporator coil the refrigerant is passes through from the compressor to the evaporator. In this situation to avoid the unwanted situation need to open the valve of the expansion.
And we should to check the condition of the evaporator in the refrigeration system.
The low discharge pressure easily can be check by the measuring instruments like Manometer and Bourdon tube gauge.
What is low discharge pressure?
When the excessive amount of refrigerant is present in the suction line of the compressor then the heat cannot flow properly across the coils of the evaporator in the refrigeration system.
In the air conditioning system simultaneously when the pressure is excessive lower than the normal pressure this condition called the low discharge pressure. In the low discharge pressure the temperature is excessive higher than the normal temperature and refrigerant is present in suction line of the compressor in a particular area.
The excessive amount of the refrigerant is present in the compressor’s suction line which is not suitable for the air conditioning system.
The coils which are used in the refrigeration system usually these are made with metal. The main reason using the metal is less power will be needed for generating the heat in the system.
The low discharge pressure is created unbalanced condition in the whole refrigeration system. In this condition the amount of pressurized refrigerant near about 65 – 75 pound per square. The refrigerant is pressurized in the compressor’s suction line and inside temperature is gradually an increase without any limitation. The low discharge pressure also slows down the refrigeration cycle.
In the refrigeration system inside the suction lime and the in the coils mainly metals are used. The metal is chosen for the systems which are good in heat conduction. The name of the metal is copper and alternatively the tungsten also can be used. With the help of the suction line the evaporator valve and the condenser’s whole unit are connected.
Low discharge pressure high suction pressure:
In this section we will discuss about the topic of low discharge pressure high suction pressure.
In the refrigeration system the low discharge pressure is generates for the bad condition of the equipment. The leakage is present in the return line of the oil separator, the piston’s condition of the compressor is not well or the discharge valve which is placed in the outside of the compressor is generate lower pressure than the regular pressure and increases unwanted temperature is excessive inside the system is appear low discharge pressure.
The condition for the low discharge pressure the capacity of the system became less.
Most of the discharges in the refrigeration system used in the industry related to the semiconductors.
Low discharge pressure type:
When the proper reason behind the low discharge pressure is not detect properly that time the pressure gauge can be used in the compressor of the refrigeration system.
The low discharge pressure for an air conditioning system is increases when the amount of insufficient compressor is more than the usual amount. So, the low discharge pressure cannot be classified only the range of the air conditioning system it can be only read by the measuring instruments.
The reading range of the air conditioning system where the low discharge pressure is appearing is between 155 PSI to 30 PSI.
The ranges of the reading for the air conditioning system is summarize briefly in below,
1. 250 PSI / 30 PSI – If the unwanted amount of air is present inside the air conditioning system then this range of reading is appearing.
2. 250 PSI / 50 PSI – From the range reading we can recognize the inside condition of the condenser. The condenser may be not cool as much it’s required or may be somewhere blocked.
3. 225 PSI / 80 PSI – This range of reading tell us that the refrigerant is present in excess amount in the compressor some leakage is present in the expansion valve and also the size is too large.
4. 200 PSI / 70 PSI – This range of reading directly shows some blockage definitely present in the refrigeration system or may be in device of the expansion.
5.160 PSI / 10 PSI – This range of reading denoted that frosting is happened inside the evaporator of the refrigeration system. This situation is happened when pressure is too low in the pipe or may be the clogged of the valve of the expansion. For resolve the problem need to check the evaporator or the evaporator valve.
6.150 PSI / 30 PSI – The range is appearing when in the cooling medium of the refrigeration cycle water is carry by the refrigeration system.
7.150 PSI / > 10 PSI – The range of reading of the air conditioning system helps to understand that, in the refrigeration system some leakage is must be present. The leakage can be easily detected by the technician. If the problem can be solve at beginning of the process then the low discharge pressure cannot be arise.
8.125 PSI / 30 PSI – The range for the refrigeration system gives us a clear concept that, the whole system is not carry the sufficient charged or may be excessive amount of oil is carry by the oil separator.
9.100 PSI / 100 PSI – The range is clearly gives us the clear concept about the condition of the compressor in the refrigeration system. In this range the compressor cannot be engage just because the brunt coil not transfers the power.
10. 50 PSI / 50 PSI – By this range of the reading we could understand the inside condition of the clutch for the refrigeration system.
Low discharge pressure cause:
In this portion of the article we will discuss about the causes of the of the low discharge pressure.
The reasons which are consider to as primary causes for the low discharge pressure is,
1. Malfunction of the thermostatic expansion valve
2. The condition of the refrigerant is when under the charge
The secondary reasons for the low discharge pressure is discuss in below section,
1. The leakage of the valve of the compressor: The common problem for the air conditioning system of the discharge valve of the compressor is the leakage. If we go through the air conditioning reading then the range of the reading is about 150 PSI. The condition in practically very hard to detects. Only the condition can be fixed by professional technician.
2. The compressor’s piston rings face the damage: The discharge gas is emitted by holes present in the compressor’s piston ring the pressure of the refrigeration cycle became low more than the regular pressure and low discharge pressure is happened in the system.
3. Leakage from oil separator to the return line:
4. Overcharged of the refrigerant:
The electronic expansion valve size is more than the normal size then the overfeeding is happened in the electronic expansion valve and the low discharge pressure is causes in the system.
5. Increasing the temperature:
When the air of the refrigeration system could not flow properly across the suction line of the compressor as a result excess amount of temperature is an increase which is not good for the system.
6. Size of the valve is excessive: The valves which are present in the air-conditioning system are larger than the regular size then the low discharge pressure is appearing.
In the article we will discuss about the topic of “High Discharge Pressure” and their related facts with types, causes, and how the high discharge pressure is related with the other parameters with several facts.
High discharge pressure can be defined as the pressure of the gas compressor’s which carrying by the suction line into the air conditioning system is facing leakage from the discharge valve is present in the compressor’s output side and combined with an indicator’s lower suction pressure.
The phenomenon named high discharge pressure of an air conditioning system can be easily fixed without facing any problem.
When the dirt is present in the compressor and if it is continuously flow by the coil in the refrigeration system then the flow of the air could not get sufficient place to flow properly in the coils and increases unwanted temperature and pressure. So, if at beginning we focus on cleaning of the dirt then high discharge pressure easily can avoided.
The problem is mainly arising from the compressor. If at the beginning of the process we go through over the compressor then this unwanted high discharge pressure can be easily avoided. If the condition of the air conditioning system is not handling immediately then the compressor it needs to repair.
In the next step we need to observe the condition of the evaporator coil. The refrigerant of the compressor passes through the outlet of the evaporator due to high temperature. In this situation the expansion valve need to open immediately to move the refrigerant.
Or the other process to control the high discharge pressure in the air conditioning system is to observe the expansion valve for the temperature and the pressure.
The phenomenon measured by the measuring instrument which is Bourdon tube pressure gauge, Manometer.
The main reason behind the high discharge pressure is excess amount of pressurized gas is present in the refrigeration system which is flowing from the compressor’s suction line to evaporator coil.
The high discharge pressure is excess amount of vaporised gas is present in the compressor’s suction line in the fixed area of the air conditioning system which is increases unwanted temperature and pressure because of the heat transfer is not happed properly.
The main reason behind this situation is the refrigerant present in the compressor of the air conditioning system is not able to transfer into heat which is carrying by the evaporator coil.
The coils are usually made with metal such as copper, tungsten which is used in the high discharge pressure in the air conditioning system. The evaporator coil and condenser unit connected with the help of suction line.
In the suction line present refrigerant is pressurized about 60 – 72 pound per square. When this amount of pressurized refrigerant is crosses the compressor the pressure is arise and thus the inside temperature is also increases. This condition can slow the whole process even can damage the air conditioning system.
The high discharge pressure is an unwanted situation which is occurs by the present of insufficient compressor of the refrigeration system in the cooling medium which may be water or gas.
The term of insufficient compressor means the leakage should be contained by the discharge valve of the compressor which is situated outside of the compressor. In the refrigeration system the refrigerant is present in the suction line of the compressor which obviously not enough for the cooling medium that could be liquid gas or water.
When the refrigerant of the compressor is not totally transfer into heat then the low head pressure is continuously increases and the pressurized range of the cooling medium became too high near about 72 PSI which is not required to the system. At the high discharge pressure the temperature of the refrigeration system is also became high than the normal temperature because of the present oil could not able to lubricate properly when the cylinders and compressor are too hot.
The chillers are works in the basic law of vapour absorption or in the law of vapour absorption.
A device by which heat can be remove with the help of the vapour compressor from a coolant which should be stayed in a liquid form in the refrigeration system is called high discharge pressure in chillers.
If we go through the refrigeration cycle then we could find t first the liquid which is present in refrigeration system is circulated in the heat exchanger for coiling the liquid. The excess amount of heat which is produced in refrigeration system during the refrigeration cycle that would be discharge in the atmosphere to balanced the whole process.
The chillers can be classified in some categories in basic of technology used in the compressor. The classification chillers name given in below,
Reciprocating chillers
Centrifugal chillers
Scroll chillers
Screw chillers
The chillers classified in the basis of system names are given below
Water chillers
Air chillers
Evaporative condensed chillers
High discharge pressure cause:
The reason of high discharge pressure is briefly summarize in below,
1. When the compressor of the air conditioning system carry the cooling medium.
The cooling medium can be water or liquid gas.
2. Temperature of the cooling medium is more than the normal temperature for the refrigeration cycle in air conditioning system.
3. Size of the evaporator is too high: If the size of the evaporator is excess than the normal size then the unbalanced situation is occurred.
4. Get not enough space to floe the refrigerant in the air conditioning system.
5. Leakage from the valve of the compressor:
In the air conditioning system one of the common problems for the phenomenon of high discharge pressure is the leakage from the compressor valve of the compressor. This is very difficult to detect but when this condition occur the gasses are emitted from the holes and the air flow is not flow properly .Thus discharge gas is moves into the compressor cylinder by the down stroke of the crankshaft.
When the sealing of the discharge valve is not done properly thus the causes low head pressure and increases the temperature .The discharge temperature became more than the usual temperature of the refrigeration cycle.
Sometimes the gases which are discharge from the compressor cylinder is run through short cycle, in this situation the flow of the present refrigerants became low. As a result the pressure and temperature became less for the heat load which is present in the condenser.
When the low refrigerant go through the condenser, the rate of the heat is reduced, means the sub cooling of condenser causes high suction pressure.
6. Damage of the piston ring of the compressor:
When the emit gasses facing leakage due to the piston ring of the compressor the pressure is developed than the normal pressure and the high suction pressure is happened. During the compressor stroke the piston ring of the compressor is produce low head pressure.
7. Leakage of the return line of the oil separator:
The purpose of the oil separator is to differentiate and control the level of the high and low sides of the air conditioning system. In the refrigeration system the oil separator is place in the higher side of the level and the compressor crankcase is situated in the lower side of the air condition system. The oil is flow by high level means the oil separator to low side of the level means in the crankcase.
If the size of the electronic expansion valve is large than the usual size then the evaporator is overfeed and causes the high suction pressure.
9. Excessive temperature:
When the flow of discharge gasses is not go properly through the suction line the temperature increases and high suction pressure is appear.
High discharge pressure type:
High discharge pressure is the inside condition of the air conditioning system. When some unnecessary situation or object is present in the refrigeration system the temperature is increases and causes a lot of problem.
The high discharge pressure is a phenomenon in the air conditioning system which is appears in present of insufficient compressor. So, the classification of high discharge pressure cannot be done only the reading of the air-conditioning system can be done.
The air conditioning system works in the between the range of 155 PSI to 30 PSI.
The reading ranges of the air conditioning system is given below,
1.100 PSI / 100PSI – In this range reading we could understand that the generated power of the refrigeration system is can not reach to the compressor thus the compressor of the air conditioning system is not properly engaged.
2.50 PSI / 50 PSI – In this reading of the range the clutch of the refrigeration system is not engaged.
3.150 PSI / 30 PSI – If the water is present in the refrigeration cycle as the cooling medium then the range is belong to the refrigeration system.
4.150 PSI / > 10 PSI – The range of the conditioning system can help to recognize us that, there should some leakage definitely present in the refrigeration system. If at this situation the technician tried to find the leakage then the condition of the refrigeration system could not go so bad but the detection of the leakage is not too easy work.
5.125 PSI / 30 PSI – The range tells us that the refrigeration system may be oil is present in the compressor of the return line from the oil separator. The alternative reason behind the range can be the charge of the refrigeration system is not enough.
In the article we will discuss about the topic of “High Suction Pressure” and their related facts with types, causes, and how the high suction pressure is related with the other parameters with several facts.
High suction pressure is the present of refrigerant to the compressor which is carrying by the suction line into the air conditioning system is facing leakage from the discharge valve which is increasing the temperature and pressure without any necessity to the system of the evaporator at its outlet.
The phenomenon high suction pressure for the air conditioning system can be easily fixed. When the dirt is contains by the coil by this situation the air flow could not flow properly by the coils and increases unwanted temperature and pressure.
The problem is mainly arising from the compressor. If at the beginning of the process we go through over the compressor then this unwanted situation can be easily avoided. If the condition of the air conditioning system is not handle by the compressor then it need to repair.
In the next step we need to observe the condition of the evaporator. The refrigerant is passes through the outlet of the evaporator due to high temperature. In this situation the expansion valve need to open to move the refrigerant.
Or the other process to control the high pressure suction in the air conditioning system is to observe the expansion valve for the temperature and the pressure.
The phenomenon measured by the measuring instrument which is, Manometer.
The main reason behind the high suction pressure is excess amount of temperature and pressure is present in the system which is flowing from the compressor of the air conditioning system.
The high suction pressure is excess amount of refrigerant is present in the evaporator’s suction line with in the fixed area of the air conditioning system which is increases unwanted temperature and pressure.
The main reason behind this situation is the refrigerant present in the evaporator of the air conditioning system is not able to transfer into heat which is carrying by the evaporator coil.
The coils are usually made with metal such as copper, tungsten which is used in the high section pressure in the air conditioning system. The evaporator coil and condenser unit connected with the help of suction line. Mainly the refrigerants present in the evaporator carrying by the suction line which could not move the heat properly.
In the suction line present refrigerant is pressurized about 60 – 72 pound per square. When this amount of pressurized refrigerant is crosses the compressor the pressure is arise and thus the inside temperature is also increases. This condition can slow the whole process even can damage the air conditioning system.
High suction pressure causes:
In this portion we will discuss the causes behind the reason of the high suction pressure. The reasons are discuss in given below briefly,
Leakage from the valve of the compressor:
In the air conditioning system one of the common problems for the phenomenon of high suction pressure is leakage of the compressor valve. This is very difficult to detect but when this condition occur the gasses are emitted from the holes and the air flow is not flow perfectly .The discharge gas is moves into the compressor cylinder by the down stroke of the crankshaft.
When the sealing of the discharge valve is not done properly thus the causes low head pressure and increases the temperature thus the discharge temperature is more than the usual temperature.
Sometimes the gases which are discharge from the compressor cylinder is run through short cycle, in this situation the flow of the present refrigerants became low. As a result the pressure and temperature became less for the heat load which is present in the condenser.
When the low refrigerant go through the condenser, the rate of the heat is reduced, means the subcooling of condenser causes high suction pressure.
Damage of the piston ring of the compressor:
When the emit gasses facing leakage due to the piston ring of the compressor the pressure is developed than the normal pressure and the high suction pressure is happened. During the compressor stroke the piston ring of the compressor is produce low head pressure.
Leakage of the return line of the oil separator:
The purpose of the oil separator is to differentiate and control the level of the high and low sides of the air conditioning system. In the refrigeration system the oil separator is place in the higher side of the level and the compressor crankcase is situated in the lower side of the air condition system. The oil is flow by high level means the oil separator to low side of the level means in the crankcase.
If the oil is could not flow properly in the air conditioning system then high pressure is occur and high suction pressure is appear.
When the refrigerant is overcharged:
If the size of the electronic expansion valve is large than the usual size then the evaporator is overfeed and causes the high suction pressure.
Excessive temperature:
When the flow of discharge gasses is not go properly through the suction line the temperature increases and high suction pressure is appear.
High suction pressure types:
High suction pressure is the inside condition of the air conditioning system. When some unnecessary situation or object is present in the refrigeration system the temperature is increases and causes a lot of problem.
High suction pressure cannot be classified the pressure reading inside the air conditioning system can be classified. The reading of the pressure measuring instrument is, Pressure Gauge.
In the air conditioning system if the suction side the pressure is increasing continuously then the low head pressure will be increasing inside the system. When the refrigeration system continuously faces the less temperature the amount of capacity will be also decreases.
When the discharge gasses facing the leakage of the piston ring of the compressor the high head pressure is appears.
The pressure is developed inside the refrigeration system more than the normal pressure. When the pressure is sudden increases the temperature is also increases. Thus, the unwanted unbalanced condition of high suction pressure is happened. During the compressor stroke the piston ring of the compressor is produce low head pressure than the normal pressure.
High suction pressure in refrigeration system:
The condition of high suction pressure in the refrigeration system is occurs just because of the absence of the insufficient compressor.
From the term for the insufficient compressor means the leakage should be present in the discharge valve of the compressor. In the refrigeration system the refrigerant present in the compressor is not enough for the cooling medium. When the refrigerant of the compressor is not totally transfer into heat this low head pressure is increases and temperature increases.
High suction pressure in heat mode:
The high suction pressure is a phenomenon where the pressurized gas is reaching about 60 -72 pounds per square and crated an imbalance situation inside the refrigeration system.
When the discharge gasses are passes through the condenser the dirt can be present in it. Mixing the dirt with discharge gasses the motion of the flow cannot be stay as same as a result the quantity of the vaporized gas is increases and the heat properly does not transfer thus the temperature is also increases and causes extreme high head pressure to the air conditioning system.
High suction pressure in heating:
When the refrigeration system is go through the condition of the high suction pressure the inside temperature and pressure is also increases.
This condition of high suction pressure in heating occurs for the insufficient compressor. From the term of insufficient compressor we easily could say that, definitely a leakage should be present in the discharge valve. In the refrigeration system the refrigerant present in the compressor is not enough for the cooling medium.
High suction pressure in heat pump:
Heat pump can be defined as, by the help of the refrigeration cycle without taking any external power the device by which hot or cool medium is flowing in a closed or domestic medium by transferring the thermal energy from a less temperature space to more temperature area.
If in the heat pump of the refrigeration cycle without taking any external power the flowing liquid could not flow in normal manner then the pressure and temperature will be increases in the refrigeration system and high suction pressure is appear.
What causes high suction pressure and high discharge pressure?
The high suction pressure is an unwanted phenomenon of the air conditioning system. The sudden increasing of the temperature and pressure not only damage the equipment but also can damage the whole system. In below the causes of this phenomenon briefly described.
Causes of the high suction pressure:
1.Heavy load of the system:
From the compressor the discharge gas is flow in a motion to the evaporator. When the gas is flow if the gaps are present in the compressor due to less uses the discharge gas could not transfer properly to the heat thus the air conditioning system became very high due to heavy load.
2.The capacity of the expansion valve of the air conditioning system is too high.
3. Leakage of the compressor’s valve
4. The capacity of the regulation is higher than the normal
5.Dirt present in the suction line and the evaporator coil
6.Unbalance of the oil flow in the oil separator
7. Subcooling of the condenser
8.Heavy size of the equipments
High discharge pressure can be described as, the pressure of the compressor in the refrigeration system is produced by the discharge gases is usually more than the normal pressure generated in the outside of the compressor.
Causes of the high discharge pressure:
1. When the compressor of the air conditioning system carry the cooling medium.
2. Temperature of the cooling medium is more than the normal temperature for the refrigeration or air conditioning system.
In the article we will discuss about the topic of “Volumetric flow rate with pressure” and their related facts and their relationship which is applied in the field of engineering.
In the piping system the pressure related to the inside net force which is applied perpendicular to the axis of the pipe or the channel and volumetric flow rate means the inside condition related to the volume of the liquid substance in the pipe or channelwhere the force is applied parallel to the pipe or the channel of the piping system. For the both condition the force is applied from the external to the object.
In the system of the piping the volumetric flow rate is a very important factor. By the help of the volumetric flow rate we could easily summarize the inside condition of the piping system.
In the inside condition of a pipe or a channel, the volume of the liquid substance is moving at a cross sectional area of the pipe or channel in a particular given time period at some standard condition where the temperature and pressure is remains unchanged.
The formula of the volumetric flow rate in piping system is,
Volumetric flow rate = (Flow velocity of the liquid substance) *(Cross sectional area of a pipe or a channel)
The mathematically form of the volumetric flow rate of the piping system is,
Q = vA
Where,
Q = Volumetric flow rate of the liquid substance
v = Velocity of the liquid substance
A = Cross sectional area of a pipe or a channel
In another word we could express that,
The volumetric flow rate is the ratio between the changes of volume with the change in time.
Formula:
The formula of the volumetric flow rate is,
Volumetric flow rate = Change in volume/Change in time
It can be expressed as,
Q = dV/dt
The unit of this parameter is cubic meter per second. The dimension can be written for the volumetric flow rate is, L3T-1.
Pressure:
In the S.I. system the parameter of pressure is measured by the units is Newton per square metre, Newton per square millimetre, Meganewton per square metre, kilo Newton per square metre. But sometimes for measuring the bigger amount the bigger pressure or bar is used. The most used unit that is used to measure the pressure is Pascal.
Pressure can be defined for the piping system is the net force perpendicularly applied to the axis of the pipe or the channel in a particular given area at a standard time.
Pressure = Net force applied / Cross sectional area of the pipe or the channel
The pressure can be mathematically expressed as,
P = F/A
Where,
P = Pressure
F= Net force applied to the pipe or channel
A = Cross sectional area
1 Pa = 1 N/ square metre and
1 kPa = 1 KN/square metre
Volume flow rate pressure relationship:
In an open system when the liquid substance is moved in a motion from one place to another place in a given particular area at a fixed temperature. If that time the net force is applied parallel axis to the pipe or the channel pressure is produced.
The volumetric flow rate pressure relationship can be written as,
F = Q/t
Where, F = Flow of the liquid substance
Q = Quantity of the flowing liquid substance in the piping system
t = Taken time to flow
The relation between the volumetric flow rate and the pressure is directly proportional. Means increasing the pressure the more volumetric flow rate as well as decreasing the pressure means less amount of volumetric flow rate arise.
Flow can be categorized with pressure in two types,
Laminar flow
Turbulent flow
Laminar flow:
Laminar flow can be defined as the particles which are present in the liquid substance are going through in a defined path at a specified area and under some standard condition.
Turbulent flow:
Turbulent flow can be defined as the particles which are present in the liquid substance are going through not in a defined path and the particles are crosses to each other at a specified area and under some standard condition.
The topic of volumetric flow rate equation with pressure we get a very clear concept from the Bernoulli’s equation.
Bernoulli’s equation: When the incompressible liquid substance is flow in a defined path in a particular area at a fixed time the particle of the liquid substance containing the energy is remain constant.
The mathematical expression for the Bernoulli’s equation is given below,
The eqn (1) only applied for the ideal incompressible liquid substance.
hL = Loss of energy in the sections between 1 and 2.
The eqn(2) is applicable for the real liquid substance.
Calculate volume flow rate with pressure:
Now we will understand this topic with the help of some problems.
Problem: Soumen have a hobby of gardening. He daily gives water to his garden by the water pipe with is attached to his houses pipeline. The volume rate of the pipe by which he gives water is 40 cubic meters per second. The diameter of the pipe is 5 meter .Now calculate the speed of the pipe.
Solution: Given data are, d = 5 meter, r =5/2 = 2.5 meter.
We know that,
V = Ah = Ad
Δ V = AΔd
Δ V/Δt = AΔd/Δt = A x v
40m3/s = π x (2.5)2 x v
[40 = 5 π x v
v = 40/5 x π = 2.54 m/s
So the speed of the pipe is, 2.54 meter per second.
Volumetric flow rate vs. pressure:
Here we will discuss about the topic of volumetric flow rate vs. pressure. These both topics are used to understand the internal condition of the piping systems and also help the process to run smoothly.
Volumetric flow rate
Pressure
Relation with velocity
The relation between the volumetric flow rate and the velocity is directly proportional. Means if the value of the velocity increases then the value of volumetric flow rate is also increases and if the value of velocity decreases then the value of volumetric flow rate is also decreases in the pipe or a channel.
The relation with the pressure and velocity is directly inversely proportional. Means the value of the velocity is increases then the value of pressure is decreases and if the value of velocity is deceases then the value of pressure is increases in the pipe or the channel of a piping system.
Classification
The types of the volumetric flow rate is, 1.Vortex meter 2.Ultrasonic meter 3.Turbine meter 4.Magnetic meter
The types of pressure is, 1.Gauge pressure 2.Absolute pressure 3.Atmospheric pressure 4.Sealed pressure or vacuum pressure
Dimension
The dimension of the flow for liquid is, M0L3T-1.
The dimension of the pressure is, ML-1T-2.
Inside condition
The volumetric flow rate is mainly used to understand that, how much the volume is present inside of the pipe or channel at a given time.
The pressure means the molecules present inside the pipe.
Formula
The formula of the volumetric flow rate is, Volumetric flow rate = (Flow velocity of the liquid substance) *(Cross sectional area of a pipe or a channel)
The formula of the pressure is,Pressure = Net force applied / Cross sectional area of the pipe or the channel
Measuring instruments
The value of the volumetric flow rate is measured by the instruments are, 1. Anemometer 2. Electromagnetic 3. Ultrasonic 4. Fluid dynamic 5. Mass flow meter 6. Positive displacement flow meter 7. Obstruction type 8. Inferential
The measuring instrument of the pressure is, 1.Manometer 2.Pressure gauge 3.Pressure tube 4.Barometer 5.Micro meter 6.Bourdon gauge 7.Piezometer
The relation between the volumetric flow rate and pressure is inversely proportional. When the liquid substance is pumped in the certain place that time pressure is increases inside of the piping system at that same time the volumetric flow rate decreases.
Yes, the volumetric flow rate is changed with the pressure.
Volumetric flow rate pressure drop:
In the laminar flow the conditions of volumetric flow rate pressure drop is arise. If the pressure drop is greater than the volumetric flow rate is also greater. The pressure drop and the volumetric flow rate are dependent with each other.
Volumetric flow rate: The volume of the liquid substance in unchanged during the motion.
Suppose a huge size amount a of physical quantities’ body is changed into a smaller physical quantities’ body, then as a result the quantity of the volume which is present in the new transformed physical body also present in the small portion of the new physical body, if the portions of the bodies are collect all together and then if they are added then the total volume for the body remain same.
Pressure drop: The pressure drop in a liquid substance can be explain as, the difference between the total pressures with two points, which a fluid is carry as a network.
In the article we will investigate the topic of “Is flow rate constant “with a focus of how it is worked in the piping system. In below we also discussing the related facts with the “Is flow rate constant.”
Yes,flow rate is constant only under some fixed standard condition. In an open system the liquid substance or gas moving in a motion of the system from one place to another place by applied net force parallel axis to the pipe or the channel at standard temperature and pressure.
In an open system through a medium in a certain time period at some standard condition the liquid substances go through in a motion by unbalanced force, this is called the flow rate.
From the law of conversion of mass we get a clear concept about the mass flow rate. The conversion of mass flow rates states that, the amount of the mass of a particular object cannot not be created or destroyed. The mass of a body is measured by lever balance.
Mass flow rate can be defined as the, an object which is containing mass is constant at standard temperature and pressurewhen force is applied to the pipe or the channel externally.
The formula for the mass flow rate is,
Mass flow rate = (Density of the liquid substance)* (Velocity of the liquid substance)* (Cross sectional area of the system)
With the help of the volumetric flow rate we could understand how much volume is inside of the pipe in the piping system.
The volumetric flow rate can be defined as the for an object the inside volume is moving in a particular space from one area to another by the external applied force.
The formula for the volumetric flow rate is,
Volumetric flow rate = flow velocity of the liquid substance * cross section area of the open system
Mathematically volumetric flow rate can be written as,
Q = vA
Where,
Q = Volumetric flow rate of the liquid substance
V = Velocity of the liquid substance
A = Cross sectional area of the open system
When we go through the above equation we easily can recognize the relation for the volumetric flow rate is, the velocity and the cross section area are directly proportional to each other. The unit of the volumetric flow rate is cubic meter per second.
If we go through of the equation of continuity the flow rate of a pipe or a channel is equal to the each and every point of the piping system. In other word we can say the rate of inflow and outflow of the pipe or channel is equal.
The flow rate is constant only for the incompressible fluids.The flow rate can be regulated by the output pressure of the pump.
The pump is a device by which the fluid is pumped in the piping system. The output pressure control by the pump with which the back pressure regulator is attached.
How is flow rate constant?
The flow rate is a very important factor of an industrial area. By the help of this parameter we could easily understand the inside condition of a pipe or a channel. This parameter reduces the cost of the process and also helps to maintain the whole system.
The flow rate constant when the density of the fluid is unchanged.In the piping system the liquid substance flow through the parallel axis of the pipe or channel at the certain crosses sectional area, in this time laminar flow can be observed.
Is volumetric flow rate constant?
The volumetric flow rate used in the engineering field in the piping system. The main purpose of the volumetric flow rate is to measure the quantity of volume, in the pipe or channel for the liquid substance. The mass flow rate used to measure the molecules in the flowing fluid.
The volumetric rate for a gas or a fluid is remains constant only when the value of volumetric flow rate is measure under unchanged conditions which is mainly imaginary.
Volumetric flow rate can be defined as the, in a 3 – dimensional cross sectional area the present gas or liquid substance is moving at a fixed temperature and pressure in a given time period.
When the liquid substance flow through a pipe or a channel in the piping system the volume of the liquid substance is close to incompressible at fixed time.
Thedimension of the volumetric flow rate is,L3T-1.
Problems on are flow rate constant and how are flow rate constant
Problem: In a water tank the water is pumped in the top of roof. The water tank is situated in the 7th floor of the house. The water is flow by the pipeline. The water is travelled by the pipes of the pipeline is 10 ft/sec.The width of the pipe is 36 inch. Now calculate the amount of flow rate of the water in the pipe.
Solution:
Given data are, v = 10 ft/sec
We know the formula of the area of the pipe is,
A = π x r2 = = 0.785 x D x D = 0.785 x 3 x 3 = 7.06 ft2
Now the volumetric flow rate formula is,
Q = Velocity of the water * Cross sectional area of the pipe
Q = 70.6 ft3/sec = (70.6ft3 x 60sec x 7.48gal)/(sec x 1min x 1ft3) = 31,685 gpm
The flow rate of the water pipe is,31,685 gpm.
Problem: In a XYZ named industry has four oil tanks. All the oil tanks are attached with the oil supplier tank. The oil has the density is 489 kg per cubic meters and velocity is 10.9 meter per second. The oil tank’s pipe diameter is about 6 cm. Determine the value of volumetric flow rate.
Solution:
Given data are, d = 6 cm, v = 10.9 m/s
Radius = r = d/2 = 6/2 = 3 cm
A = π x r2 =π x 32 = 28.26 cm2 x 1m2/100 cm2 = 0.2826 m2
Q = A x v = 0.2826 x 10.9 = 3.080 cubic meter per second.
Solution: When the liquid substance flow through a pipe the tendency of the liquid is to maintain the volume. In this condition the liquid is incompressible.
An incompressible liquid substance which is flow in a certain amount of cross sectional area through a channel or a pipe at a fixed time period then quantity of the liquid substance which is passes in the piping system is same and each section of the pipe or the channel. This is the Equation of continuity.
Mathematically it can be expressed as,
Q1 = Q2 = Q3 =Q4 =…………….
a1v1 = a2v2 = a3v3 = a4v4 = …………..
Problem: In a house a water tank is situated in the roof of the house. The water is supply in the whole house through the pipe lines which are attached with the water tank. The water flows through the pipe 0.9 meters per second. Now from where the flow is emitted that is the one third of the sourcing pipe. Determine the amount of speed at which the water is flow through the pipeline.
Solution: Given data, v1 = 0.90 meters per second
We know the equation of continuity is,
A1v1 = A2v2
A2 = 1/3A1
A2 = 1/3A1v2
v2 = 3 x v1= 3 x 0.90 meter/second = 2.7 meter per second
The amount of speed at which the water is flow through the pipe is, 2.7 meter per second.
Question: What is the alternative formula of the volumetric flow rate?
Solution: The another way to write the volumetric flow rate is,
Volumetric flow rate =Q = V/t ……eqn(1)
In a pipe from where the fluid is flowing there volumetric flow can be written as,
V = Ad …..eqn(2)
Where, V = Volume of the liquid in the pipe
A = Cross sectional area of the flowing fluid in the pipe
d = Width of the pipe
Now we could write volumetric rate for the cylindrical pipe is,
Q = V/t = Ad/t
The term d/t is written for express the fluid is flowing in a fixed time in fixed diameter of the pipe.
Comparing the eqn (1) and eqn (2) we get,
Q = Av [v = d/t]
Where, A = Cross sectional area of the pipe in the piping system.
We also know that, the formula for the area,
A = π x r2
So in the above equation we get three parameters.
1. If area and density if given then we easily can calculated the value of velocity.
2. In another way if density and velocity given then we also can calculated the value of area.
3. And finally velocity and area is given then the value of density of the liquid we can calculate.
Question: What is the incompressible fluid?
Solution: In all liquid substance the incompressible flow is visible.
Incompressible flow: When a liquid substance is flow in a certain amount of a cross sectional area at a given time period at fixed temperature and pressure, if that time the velocity and the density of the flied substance s remain unchanged is called incompressible flow.
What is incompressible liquid?
Solution: Water flow in a pipe or a channel in the piping system the incompressible liquid is present.
Incompressible liquid: When the fluid is moving in the piping system through a pipe or a channel at a given area in fixed time period, that time if the density and the velocity is remain unchanged is called the liquid as incompressible liquid.
In the article we will discuss about the topic of Mass flow rate to volumetric flow rate and their related facts and the application of Mass flow rate to volumetric flow rate in the flied of engineering and their purposes.
For the getting value of volumetric flow rate from mass flow rate we need to divide the value of mass flow rate by the density.
Mass flow Rate:
From the law of the conversion of mass we get a clear concept of the mass flow rate. The mass flow rate remains constant at a standard condition where time and pressure are fixed, if no mass added or removed from the external source to the object.
Mass flow rate can be defined as the mass of a liquid substance is moving at a fixed time period from a given a cross sectional area at a constant pressure and temperature.
With the help of the mass flow rate we could measure the molecules which are present in the flowing liquid through the measurement instruments.
Volumetric flow rate:
In the piping system the volumetric flow rate is a vital factor. By this volumetric flow rate we could summarize the condition of the fluid.
In the inside of the pipe, the volume of fluid is flowing at a cross sectional area in a particular time period at the standard condition where the temperature and pressure is constant.
Mass flow rate = (Density of the fluid)* (Velocity of the liquid)* (Cross sectional area)
Mathematically it can be expressed as,
ṁ = ρVA
Where, ρ = Density of the flowing fluid
V = Velocity of the liquid substance
A = Cross sectional area
From the above equation the mass flow rate can be easily recognize that, the mass flow rate depend on the density, velocity and area and it is has direct relation with these three parameters
In another word mass flow rate also can be expressed as, ratio between the change in mass of the liquid substance to the change in fixed time.
Numerically it can be expressed as,
ṁ = dm/dt
The unit of the mass flow rate is kilogram per second (kg/s). In the equation the is mainly used to classified from regular m, which we are generally used in work purpose.
Volumetric flow rate:
The formula of the volumetric flow rate is,
Volumetric flow rate = (Flow velocity of the fluid) *(Cross sectional area)
Mathematically the form of the volumetric flow rate is,
Q = vA
Where, Q = Volumetric flow rate of the fluid
v = Velocity
A = Cross sectional area
In another word volumetric flow rate defined as the ratio between the changes of volume with the change in time.
It can be expressed as, Q = dV/dt
After study the formula of the volumetric flow rate we found that, the volumetric flow rate mainly dependent on the velocity of the fluid and area. The unit of this parameter is cubic meter per second. The dimension of the volumetric flow rate is, L3T-1.
How do you convert mass flow rate to volume flow rate?
Mass flow rate of a piping system is the total mass is moving in a material.In numerically the mass flow rate expressed in pounds. In another way the volumetric flow rate is total volume is moving for a material. Numerically the volumetric flow rate expressed as cubic feet.
Convert mass flow rate to volume flow rate: At the beginning of the process the mass flow rate is divided by the density of the flowing fluid. After the division which result is coming that is the volumetric flow rate value. Numerically this is expressed as cubic feet.
In generally when we considering the measuring for flow that time liquid substance and gases are consider for an object. The mass of an object considered as density which contained the volume for the object. It can be express as pounds per cubic foot.
Example:
Suppose the mass floe rate for an object is 200 pounds and density is 20 pounds in cubic feet, then the volumetric flow rate is,
Is volumetric flow rate the same as mass flow rate?
The volumetric flow rate mainly used to measure the amount of volume present in the fluid where as the mass flow rate used to measure the molecules in the flowing fluid.
Volumetric flow rate can be defined as the, in a 3 – dimensional area the present gas is flowing at a fixed temperature and pressure in a given time period.
Mass flow rate can be defined as the molecules present in the liquid substance are flow through in a given cross sectional area at standard condition.
Problems on how to convert mass flow rate to volume flow rate:
Problem: In the house of Rajesh he filled a water tank with the help of a pipe. The radius of the pipe is 3 cm. When Rajesh filled the tank he takes 2 hours. The velocity of the water which is flow through the pipe is 8.2 m/s. Assume the density of the water is 940 kg/cubic per meters. Find the volumetric and mass flow rate.
Solution: We know that,
Area for the pipe is,
The volumetric flow rate for the pipe is,
The mass rate for the pipe is,
Frequently asked questions:
Problem: A water tank is totally full with a fluid. The fluid is flowing in the water tank at a speed of 90 meters per second. The total area of the water tank is 0.9 square meters. The fluid carry the density amount is 1.6 grams per cubic meters. Calculate the mass flow rate for the fluid in the water tank.
Solution: Given data,
ρ = 1.6 grams per cubic meters
A = 0.9 square meters
V = 90 meters per second
We know that,
ṁ =ρ VA
ṁ= 1.6 x 0.9 x 90 = 129.6 grams per second.
The mass flow rate for the liquid in the water tank is 129.6 grams per second.
Problem: Determine the diameter of the pipe. A pipe which is attached with the water tank through this the water is flowing. The mass flow rate of the water which is flow by the pipe is 120 grams per second. The density and the velocity of the water respectively are 1.2 grams per cubic meter and 0.2 meter per second.
Solution: Given data are,
ṁ = 120 grams per second
ρ = 1.2 grams per second
V = 0.2 meter per second
We know that,
ṁ = ρVA
A = m/ρV = 120/1.2 x 0.2 = 500 sq. metre
Now we also know that, the formula of the cross sectional area is,
A = π x R2
Here, r = Radius
d = 119.52 meter So, the diameter of the pipe is 119.52 meter.
In this article we will investigate the topic of Flow vs. Pressure with a focus on how they are worked in the various fields and their applications in the various industrial areas.
Flow
Pressure
Definition
Flow can be describe as the measurement for any device that air is emitted from that device at any point in time that is given in terms of volume.
Pressure can be describe as the measurement for any device that, at any point in time that is given for an area the force is applied to determine the performance of the compressor which is able to perform in a differentiate the portion of the work.
Unit
The unit of the Flow is cubic feet per minute (cfm).cubic meter per second (cms), gallon per second (gps), gallon per minute (gpm).
In S.I. system the pressure is measured the units are, Newton per square metre, Newton per square millimetre, Meganewton per square metre, kilo Newton per square metre. But sometimes foe measure the bigger amount the bigger pressure or bar is used. The another unit that is also used to measure the pressure is Pascal.
Application
The application of the measurement of flow in the various water recourses such as controlling the water resource system, designing and many others.
The application of the pressure is prevent from sinking the base of the construction of the building or dams and many others.
Dimension
The dimension of the flow for liquid is, M0L3T-1.
The dimension of the pressure is, ML-1T-2.
Deviation from other quantities
Q =vA
p =F/A
Types
The types of flow is 1.Laminar flow 2.Turbulent flow Laminar flow again divided in three categories, 1.Unidirectional laminar flow 2. Pulsatile laminar flow 3.Oscillatory laminar flow The types of pressure is, 1.Atmospheric pressure 2.Absolute pressure 3.Gauge pressure
The relation between the flow and the pressure is directly proportional.
Flow:
The meaning of the flow is when a liquid substance goes through in a motion at a specific time at the given cross sectional area of the system.
The flow rate can be defined as the mass of the fluid is flowing per unit area at a standard temperature and pressure.
In an open system by the process the mass of the liquid substance is move one area to another area in a fixed time at a standard pressure.
Pressure graph:
The pressure graph actually looks like a hyperbola.
For draw a pressure graph at first we need to plot the pressure variable horizontally means along with the x axis. After that vertically means along with the y axis we will plot the volume variable. Then the value of the pressure which we get from the experiments should be pointed in the graph.
From the above equation we easily can relate the relation is the volumetric flow rate is directly proportional to the velocity and the cross section area. The unit of the flow rate is cubic meter per second.
The relation between the flow and the pressure is directly proportional. If the pressure increases at a standard temperature then the flow also increases and if the pressure is decreases then the flow is also decreases.
Pressure relationship:
Only for an ideal gas which has fixed mass and standard temperature there only the pressure relationship applicable. This topic easily can describe from the Boyle’s law. This law is founded by Robert Boyle in1662.
Boyle’s Law: The Boyle’s law states that, in a fixed mass for an ideal gas the absolute pressure is inversely proportional to the ideal gas volume.
Mathematically it can be expressed as,
ρ ∝ 1/v
pv = Constant … eqn (1)
Where, p = Pressure
v = Volume
The more effective form of the eqn (1) is,
p1v1 = p2v2 = p3v3 = ………..= Constant
The suffixes uses in the above formula is denoted the different conditions.
Flow vs pressure trigger:
The term triggering is attached with the other physical quantities, they are respectively, motion, pressure, impedance, flow and volume.Triggering means the signal which is shown the inspiration.
Flow trigger:
In the mechanical ventilation flow trigger is the one of the most popular method. Flow trigger mainly works in the bias flow.
Flow trigger is allowing the patient who is present in the mechanical ventilation to initiate foe breathing.
Pressure trigger:
In the mechanical ventilation, the flow trigger is designed as that process where the airway pressure would be decreases thus the pressure trigger is appear. The pressure trigger increases the breathing of the patient.
In the mechanical ventilator system the drop of the airway pressure is detected with the help of the inspiratory effort.
Hydraulic flow vs pressure:
Hydraulic flow:
In the piping system the hydraulic flow one of the important factor. In the area of the engineering the engineers are used the hydraulic flow to determine the volumetric flux and also how much power should be required to a pump a fluid.
In a specified time period liquid substance is flow in a particular given area is called Hydraulic flow.
Hydraulic flow is also known as flow rate. The unit of the flow rate is cubic metres per second.
Pressure:
Pressure can be expressed s atmospheric pressure.
The pressure which is available in the atmosphere of the earth’s radius is known as atmospheric pressure.
Centrifugal pump flow vs pressure:
Centrifugal pump flow:
In a centrifugal pump there mainly three types of flow can be present. The types of flow are: Rapid flow, axial flow and mixed flow. This pump is also known as Turbine pump.
Centrifugal pump can be defined as the a mechanical device by which the fluid is go through by the impeller (driven motor).In the centrifugal pump the fluid is transfer its energy to rotational energy by the impeller.
Pressure:
In S.I. unit there are lots of partial units are present to express the pressure, mainly Pascal is used to measure the pressure. Pascal is related to the other partial units is given below,
1 Pa = 1 N/ square metre and
1 kPa = 1 KN/square metre
When the perpendicular force is applied to a particular given surface is called pressure.
Flow rate vs pressure in pipe:
Flow:
Flow is measure by the digital flow meter instrument. The common type of the flow meter used in the industrial area are given below,
In the piping system the liquid substance flows through the pipe at a certain time period. For this reason the property of the physical bodies we easily can recognize. These physical properties are density and dynamic viscosity. By this we easily can determine the kinematic viscosity.
When the fluid is flow through a pipe in a certain time period at a unit time pressure is occur in this way, this condition called pressure in pipe.
At first we will decide which material should be used in the pipe for the piping system. Then we could estimate how much length (L) of the pipe we will use in this process from the layout of the construction. From here we easily could find the roughness of the pipe. In the piping system the fluid is pumped that causes corrosion in the material present on the pipe. Now in the whole process three parameters are appearing.
The parameters respectively are head loss, pressure drop and mass flow rate. From the factor of pressure in pipe the cost of the system can reduce and helps to flow the process in a perfectly manner. If any two parameters are given from there the third one we can find so easily.
3. And at the last case mass flow rate and head loss given, then pressure drop also can be determine.
Flow vs pressure drop:
Now we will discuss about the topic of flow vs. pressure drop.
Flow:
A pressure gradientis very important factor for a fluid to flow. If the pressure gradient is high to a system then the flow of a fluid is also high, and if the pressure gradient is low to a system then the flow of a fluid is also low.
Flow can be defined as the, in a certain time the amount of fluid is passes.
Pressure drop:
In piping system the pressure drop is a very important factor. With this pressure drop factor the examiner of the engineering field get a lot of benefits. They design the piping system with this pressure drop which helps them to determine the diameter of the pipe, specifications of the pipe, which valve should to be used and many others.
Pressure drop can be derives as the difference between the total pressure with two points, which a fluid is carry as a network.
Pressure drop or head loss has a relation with the Fanning friction factor f is,
In a alternative way the pressure drop can be written as,
Flow vs. Pressure relationship:
In this section we will briefly summarize the topic of Flow vs. Pressure relationship.Flow and pressure both are the key factor for the measuring of compressed air system, which is helps us to understand the size of the compressor which is used in the system and also the power is applied to the system with the amount of the flow rate and air volume.
Flow:
When unbalanced force is applied in an open system to an object the motion is generared, which is call the flow.
Pressure relationship:
For a particular given mass in an ideal gas absolute pressure is directly proportional to the absolute temperature.
When it comes to fluid dynamics, one of the key concepts to understand is the mass flow rate. The mass flow rate refers to the amount of mass that passes through a given point in a system per unit of time. In certain situations, the mass flow rate remains constant, regardless of changes in other variables. This phenomenon is known as a constant mass flow rate. Understanding this concept is crucial in various fields, such as engineering, physics, and environmental science, where the movement of fluids plays a significant role.
Key Takeaways:
Mass Flow Rate Constant
Definition
Formula
Units
Factors Affecting
Applications
Understanding Mass Flow Rate
Mass flow rate is an important concept in fluid dynamics and is used to measure the amount of mass that passes through a given point in a system per unit of time. It is a fundamental principle in the study of fluid mechanics and is based on the conservation of mass.
The mass flow rate can be calculated using the equation:
Mass Flow Rate = Density of Fluid × Volumetric Flow Rate
where the density of the fluid is the mass per unit volume and the volumetric flow rate is the volume of fluid passing through a given point per unit of time. This equation allows us to determine the mass flow rate by knowing the density of the fluid and the volumetric flow rate.
Is Mass Flow Rate Always Constant?
In many cases, the mass flow rate remains constant throughout a system. This is because of the principle of mass conservation, which states that mass cannot be created or destroyed. Therefore, the mass flow rate into a system must equal the mass flow rate out of the system, assuming no mass is being stored within the system.
Why is Mass Flow Rate Constant?
The constant mass flow rate is a result of the continuity equation, which is based on the principle of conservation of mass. According to this equation, the mass flow rate remains constant in a steady flow system, where the flow velocity and the density of the fluid remain constant. This means that as the flow velocity increases, the cross-sectional area of the pipe must decrease to maintain a constant mass flow rate.
When is Mass Flow Rate Constant?
The mass flow rate is constant in a steady flow system where there are no changes in the flow velocity, density of the fluid, or cross-sectional area of the pipe. This is often the case in many practical applications, such as in pipe flow or flow through a nozzle. In these situations, the mass flow rate can be easily calculated using the mass flow rate equation mentioned earlier.
Understanding the concept of mass flow rate is crucial in fluid dynamics and has practical applications in various fields. It helps in designing efficient systems, determining the performance of flow meters, and understanding the behavior of fluids in different scenarios, whether it is incompressible flow or compressible flow.
Remember, the mass flow rate is a measure of the amount of mass passing through a point in a system per unit of time. By understanding the mass flow rate equation and the factors that affect its constancy, we can gain valuable insights into the behavior of fluid flow and its impact on various processes.
Mass Flow Rate in Different Scenarios
In fluid dynamics, the mass flow rate is a fundamental concept that describes the amount of mass flowing through a given cross-sectional area per unit time. It is a crucial parameter in various scenarios, including turbines, nozzles, and compressible flow. Let’s explore each of these scenarios to understand if the mass flow rate remains constant.
Is Mass Flow Rate Constant in a Turbine?
When it comes to turbines, the mass flow rate is not constant. Turbines are devices that convert the kinetic energy of a fluid into mechanical work. As the fluid passes through the turbine, its velocity and pressure change, resulting in a change in the mass flow rate. According to the principle of conservation of mass, the mass flow rate remains constant in an isolated system. However, in a turbine, the mass flow rate varies due to the conversion of kinetic energy into work.
Is Mass Flow Rate Constant in a Nozzle?
Similar to turbines, the mass flow rate is not constant in a nozzle. Nozzles are designed to accelerate the flow of fluid by increasing its velocity while decreasing its pressure. As the fluid passes through the nozzle, its velocity increases, leading to a decrease in pressure according to Bernoulli’s principle. Consequently, the mass flow rate changes as the fluid undergoes this acceleration process.
Is Mass Flow Rate Constant in Compressible Flow?
In compressible flow, where the density of the fluid changes significantly, the mass flow rate is not constant. Compressible flow occurs when the fluid’s density varies due to changes in pressure, temperature, or velocity. The continuity equation, a fundamental principle in fluid mechanics, states that the mass flow rate remains constant in an incompressible flow. However, in compressible flow, the density of the fluid changes, resulting in a varying mass flow rate.
To better understand the concept of mass flow rate in different scenarios, let’s summarize the key points in a table:
Scenario
Is Mass Flow Rate Constant?
Turbine
No
Nozzle
No
Compressible Flow
No
As we can see, the mass flow rate is not constant in turbines, nozzles, or compressible flow scenarios. Understanding the variations in mass flow rate is crucial for various applications, such as flow rate calculations, pipe flow analysis, and the design of fluid flow systems.
Remember, the mass flow rate is a fundamental parameter in fluid dynamics, and its variations in different scenarios are governed by the principles of conservation of mass, Bernoulli’s principle, and the continuity equation.
Practical Applications and Problems
Fluid dynamics and the conservation of mass are fundamental concepts in fluid mechanics. Understanding these principles is crucial for solving various problems related to fluid flow. In this section, we will explore practical applications and problems that involve calculating mass flow rates and other related parameters.
Problem: Calculating Mass of Air Discharges in a Nozzle
One common problem in fluid mechanics is determining the mass of air discharged through a nozzle. This calculation is important in applications such as jet engines, where the mass flow rate of air affects the engine’s performance. To solve this problem, we can utilize the principles of Bernoulli’s equation and the continuity equation.
The Bernoulli’s principle states that in a steady flow of an incompressible fluid, the sum of the pressure, kinetic energy, and potential energy per unit volume remains constant. By applying this principle and considering the flow velocity and density of the fluid, we can calculate the mass flow rate through the nozzle.
Problem: Calculating Mass Flow Rate in a Tank
Another practical problem involves determining the mass flow rate of fluid entering or leaving a tank. This calculation is essential in industries such as chemical engineering, where accurate measurements of mass flow rates are crucial for process control. To solve this problem, we can use the concept of the continuity equation.
The continuity equation states that for a steady flow of fluid in a pipe, the mass flow rate is constant. By considering the cross-sectional area of the pipe and the fluid velocity, we can calculate the mass flow rate in the tank. This information is valuable for monitoring and optimizing the fluid flow in various industrial processes.
Problem: Calculating Mass Flow Rate in a Cylinder
In some applications, it is necessary to determine the mass flow rate of fluid in a cylinder. This problem often arises in hydraulic systems, where the mass flow rate affects the performance of the system. To solve this problem, we can apply the principles of fluid mechanics and the continuity equation.
By considering the cross-sectional area of the cylinder and the fluid velocity, we can calculate the mass flow rate. This information is crucial for designing and optimizing hydraulic systems, ensuring efficient and reliable operation.
Problem: Calculating Mass Flow and Power in a Reaction Turbine
The calculation of mass flow and power in a reaction turbine is another practical problem in fluid mechanics. Reaction turbines are commonly used in power generation systems, where the mass flow rate and power output are critical parameters. To solve this problem, we can utilize the principles of fluid dynamics and the conservation of mass.
By considering the flow velocity, density of the fluid, and the pressure change across the turbine, we can calculate the mass flow rate and power output. This information is essential for designing and operating efficient power generation systems.
In summary, understanding the principles of fluid dynamics, conservation of mass, and various calculations related to mass flow rates is crucial for solving practical problems in fluid mechanics. Whether it’s calculating the mass of air discharged in a nozzle, determining mass flow rates in tanks and cylinders, or analyzing the performance of a reaction turbine, these concepts play a vital role in various engineering applications.
Frequently Asked Questions
What is the Mach Number and its Importance?
The Mach number is a dimensionless quantity that represents the ratio of the flow velocity of a fluid to the local speed of sound. It is named after the Austrian physicist and philosopher Ernst Mach. The Mach number is important in fluid dynamics, especially in compressible flow, as it helps determine the behavior of the fluid and its interaction with objects in its path.
The importance of the Mach number lies in its ability to indicate whether the flow is subsonic, transonic, or supersonic. In subsonic flow, the Mach number is less than 1, indicating that the flow velocity is slower than the speed of sound. Transonic flow occurs when the Mach number is close to 1, and supersonic flow happens when the Mach number exceeds 1. These distinctions are crucial in understanding the characteristics of fluid flow and designing efficient systems.
Where is the Mass Flow Rate Applied?
The concept of mass flow rate is applied in various fields, including fluid mechanics, engineering, and physics. Mass flow rate refers to the amount of mass that passes through a given cross-sectional area per unit time. It is a fundamental quantity used to describe the movement of fluids and is often denoted by the symbol “ṁ.”
In fluid mechanics, the mass flow rate is used to analyze and predict the behavior of fluids in pipes, channels, and other flow systems. It helps determine the velocity, pressure, and density of the fluid at different points along the flow path. Understanding the mass flow rate is crucial for designing efficient systems, such as pipelines, cooling systems, and hydraulic systems.
Is Mass Flow Rate Conserved?
Yes, mass flow rate is conserved in a closed system according to the principle of conservation of mass. This principle states that the mass of a system remains constant over time, provided that no mass is added or removed from the system.
In the context of fluid dynamics, the conservation of mass is expressed through the continuity equation. This equation states that the mass flow rate at any point in a steady flow system is constant. It means that the mass entering a given section of a pipe or channel is equal to the mass exitingthat section. This principle holds true for both incompressible and compressible flows, as long as the system remains closed.
What is Mass Flow Rate Isentropic?
Mass flow rate isentropic refers to the condition where the flow of a fluid remains reversible and adiabatic, with no heat transfer or energy loss. In an isentropic process, the entropy of the fluid remains constant.
In the context of fluid flow, maintaining an isentropic mass flow rate is desirable in certain applications, such as gas turbines and compressors. It ensures that the flow remains efficient and minimizes energy losses. By maintaining an isentropic mass flow rate, the system can achieve maximum work output or efficiency.
In summary, understanding the Mach number and its importance helps analyze fluid behavior, while the mass flow rate is applied in various fields to describe fluid movement. Mass flow rate is conserved in a closed system, and maintaining an isentropic mass flow rate ensures efficient flow. These concepts are fundamental in fluid dynamics and play a crucial role in designing and optimizing fluid flow systems.
Conclusion
In conclusion, the concept of mass flow rate being constant is crucial in various fields, especially in fluid dynamics and engineering. The mass flow rate refers to the amount of mass passing through a given point per unit time. When the mass flow rate is constant, it means that the rate at which mass enters a system is equal to the rate at which it exits. This principle is essential for the proper functioning of many systems, such as pipelines, ventilation systems, and chemical processes. By ensuring a constant mass flow rate, engineers can maintain stability and efficiency in these systems, ultimately leading to better performance and reliability.
References
Fluid dynamics is a branch of fluid mechanics that studies the motion of fluids, including gases and liquids. It involves the principles of conservation of mass and energy, as well as the analysis of fluid flow and its properties. One of the fundamental concepts in fluid dynamics is the conservation of mass, which states that the mass of a fluid remains constant within a closed system.
In fluid dynamics, volumetric flow rate refers to the volume of fluid that passes through a given cross-sectional area per unit of time. It is a measure of how quickly the fluid is flowing and is often denoted as Q. The volumetric flow rate can be constant in a steady flow, where the flow velocity and the cross-sectional area remain constant.
Bernoulli’s principle is another important concept in fluid dynamics. It states that in a steady flow of an incompressible fluid, the sum of the flow velocity, the potential energy per unit volume, and the pressure energy per unit volume remains constant along a streamline. This principle helps explain the relationship between flow velocity, density of the fluid, and pressure change in a fluid system.
Pipe flow is a common example of fluid flow in many engineering applications. The continuity equation, which is derived from the conservation of mass, is used to analyze pipe flow. It states that the product of the cross-sectional area and the flow velocity of a fluid remains constant along a streamline.
In a constant flow system, the fluid flow rate remains constant over time. This can be achieved by using flow control devices such as valves or flow meters. Flow meters are instruments used to measure the flow rate of a fluid, and they come in various types, including differential pressure meters, turbine meters, and electromagnetic meters.
The fluid velocity is an important parameter in fluid dynamics. It determines the rate at which the fluid flows and affects the pressure distribution within the fluid. The velocity can be calculated using the flow rate and the cross-sectional area of the flow.
In compressible flow, the density of the fluid changes significantly due to variations in pressure and temperature. This type of flow is commonly observed in gases. In contrast, incompressible flow refers to the flow of fluids where the density remains constant.
In conclusion, fluid dynamics is a fascinating field that involves the study of fluid flow and its properties. Understanding concepts such as conservation of mass, volumetric flow rate, Bernoulli’s principle, and pipe flow is essential for analyzing and designing fluid systems. By applying the principles of fluid dynamics, engineers and scientists can develop efficient and effective solutions for various applications.
Frequently Asked Questions
What is the relationship between thermodynamics and fluid dynamics?
Thermodynamics is the study of energy and its transformations, while fluid dynamics is the study of the motion of fluid substances. Both fields intersect when considering energy transformations in fluid systems, such as heat transfer, work done by or on the fluid, and changes in the internal energy of the fluid.
How does mass flow rate maintain constant velocity in fluid dynamics?
In fluid dynamics, the mass flow rate can maintain a constant velocity if the cross-sectional area of the flow and the density of the fluid remain constant. This is based on the continuity equation, which states that the mass flow rate is equal to the product of the fluid’s density, the cross-sectional area of the pipe, and the flow velocity.
Is mass flow rate always conserved in fluid mechanics?
Yes, mass flow rate is always conserved in fluid mechanics. This principle is known as the conservation of mass, which states that the mass of a system must remain constant over time. This means that the mass flow rate entering a system must equal the mass flow rate leaving the system, assuming no accumulation of mass within the system.
What is the mass flow rate in fluid dynamics?
In fluid dynamics, the mass flow rate is the mass of a fluid passing through a given surface per unit time. It is calculated by multiplying the fluid’s density by its volumetric flow rate.
How does the mass flow rate behave in an isentropic process?
In an isentropic process, which is a thermodynamic process that is both adiabatic (no heat transfer) and reversible, the mass flow rate remains constant. This is because the density and velocity of the fluid do not change, assuming the cross-sectional area of the flow remains constant.
Why is the mass flow rate constant in fluid dynamics?
The mass flow rate remains constant in fluid dynamics due to the principle of conservation of mass. This principle states that the mass of a fluid entering a system must equal the mass leaving the system, assuming no accumulation of mass within the system.
Is the mass flow rate constant in a nozzle?
Yes, the mass flow rate is constant in a nozzle. According to the continuity equation, the product of the cross-sectional area, flow velocity, and density of the fluid remains constant. So, if the cross-sectional area decreases in a nozzle, the flow velocity increases to maintain a constant mass flow rate.
Is the mass flow rate constant in compressible flow?
In compressible flow, the mass flow rate can remain constant if the system is in a steady state, meaning the conditions at any point in the system do not change over time. However, changes in pressure and temperature can affect the fluid’s density, which may impact the mass flow rate.
When is the mass flow rate constant in fluid dynamics?
The mass flow rate is constant in fluid dynamics when the system is in a steady state, and there are no changes in the fluid’s density or the cross-sectional area of the flow. This is based on the principle of conservation of mass.
Is the mass flow rate always constant in fluid mechanics?
In fluid mechanics, the mass flow rate is not always constant. It can vary depending on changes in the fluid’s density, the cross-sectional area of the flow, and the flow velocity. However, in a steady-state system with no changes in these parameters, the mass flow rate remains constant.
In this article we will discuss about the “Low discharge superheat” and its related factors.
The Low discharge superheat is when the refrigerant liquid flooding to the compressor or in the screw compressor in the very low oil temperature. The insufficient amount of air flows through the evaporator coils causes low discharge superheat.
With a high ambient temperature the refrigerant liquid go back to the compressor which causes the leakage to the heat exchangers and liquid injection device if it is fitted. This condition also point to an Actuator or Check valve issue. A dirty air filter, evaporator coil or air flow causes discharge measure low. The heat which is carried by the coils is low which result in low discharge superheat.
Process:
The low discharge superheat can be obtaind by the following,
At first we need to run the refrigeration system minimum for 10 min.
When the system running for a while we have to attach the pipe clamp thermocouple in one side of the refrigerant line which actually separate the thermal expansion valve and the condenser discharge valve.
Connect with the refrigerant manifold gauges with discharge service valve.
Read refrigerant manifold gauge to check the discharge service valve.
Check the thermocouple temperature using a digital thermometer.
Now need to turn over the condenser pressure reading to a condenser saturation temp.
Pressure takes from the thermocouple and the temperature of the condenser saturation from it.
Formula:
The low discharge superheat is calculated in the way as any other discharge superheat calculated on a system, by measuring the low discharge superheat and have to subtract the suction superheat and then then leaves with a figure of how much low superheat the compressor has given through compression and mechanical/electrical inefficiencies.
Work:
Prevent damage the machine from worn rings, acid formation and oils breakdowns and make it run more effective.
Example:
Let, the Discharge Temperature = 152, Condensing Sat. Temp. = 91
Then the discharge superheat would be = 61
Exhaustive facts:
In the discharge superheat refrigerant is saturated with oil causes low discharge superheat. Low discharge superheat can causes low temperature to the compressor, if the condition goes more low and low then it could damage the compressor too.
What does a low superheat indicate?
The low discharge of a system means refrigerant liquid floods to the compressor for the load is present through the evaporator coil.
When excess amount of refrigerant is enter into the coil or excessive amount of heat present into coil to vaporize the refrigerant properly,that time this condition appear.
Flooding to the compressor with the refrigerant liquid through the evaporator coil. The situation mostly happened when the expansion valve overfeeding to the evaporator or faulty of an actuator.
Pressure is too high.
Low evaporator air flow.
Temperature is low.
The shape of the system is over sized during discharge of a superheated liquid.
Reduced airflow through the evaporator.
Due to low cooling water flow or dirty tubes the refrigerant charge may be excess.
Over charged of refrigerant liquid or oil.
Low discharge superheat trane chiller:
With the help of the compressor’s discharge temperature the inside condition of the refrigeration or air conditioning system easily can be recognize. In other term the discharge temperature describe as a measurement of the superheated refrigerant’s vapour temperature.
This is used to point an actuator or check the valve issue. The Trane chillers are used to system for improve the efficiency mechanical or electrical to the compressor,deliver the correct amount of the temperature, humidity. During the flooding of the refrigerant liquid or oil the sound of the system is increases, with the Trane chillers the sound became less which impact is good for the environment .The Trane chillers deliver ventilation for the space and also helps to minimize the operating cost.
York yvaa low discharge superheat:
The low discharge superheat faults due to reason of the quantity of oil in the oil separator causes York Yvaa low discharge superheat. For this reason the oil charge is reduced in these specific circuits to correct the nuisance superheat trips. The change is only applicable to the circuits.
Procedure:
The first step is to identify the unit and the amount of the oil. The oil should be taken as that much quantity with which it could be removed as per the corresponding compressor.
As per the correct size the compressors are verified.
Need to walkout the unit.
After that need to discharge the unit.
A container is used which should be have measuring indicators gradually.
In the next step required oil is removed from the container.
The oil is separate from the compressor on the oil line.
In the starting if the refrigerant was removed from the low discharge superheat then make sure to correct the refrigerant level.
Adding the adjusted refrigerant to the system.
Apply unit to the system.
For about one hour the unit should be operate at full load.
Finally need to note down the oil level from the oil separator.
York low discharge superheat:
Low discharge superheat usually the situation occurs because of overcharge of refrigerant or overcharge of oil. Both condition gives lower discharge temperature. Once the refrigerant is saturated with oil low discharge will continue to occur.
Low discharge superheat sensor:
In the low discharge superheat all chillers will have a certain amount of the oil in the refrigerant, a little amount of oil is good but the system but too much is not good for the entire system. An excess amount of present of oil can cut blade from the impeller and reduce the efficiency of the compressor and also minimize the percentage of the heat transfer. For the recovery from this unwanted situation in the low discharge superheat’s chillers recovery equipment is needed, the recovery equipment is called the low discharge superheat sensor.
The main purpose of the sensor is to sense the oil which is float on the top of the refrigerant. The low discharge superheat condition is happened when the refrigerant liquid flooding into the compressor, or in the case of screw compressor, low cold oil temperature.
Low discharge superheat in chiller :
In the application field after doing the investigation we could find that the performance of the chillers attached with an electronic expansion valve. The chillers mainly work in steady state and transient condition. .The chillers capacity works in both hot and cold starts.
In low pressure the chillers start to work, at this condition the refrigerant enter to the evaporator. In case of low discharge superheat the capacity is very fast. In the cooling condition the chillers leading to low off/on cycling losses. The expansion valve works on the both steady and transient state of the chillers.
The capacity of the chillers is about 25 kW. The chillers mainly consists four components. The components are compressor, evaporator, expansion unit and condenser. Every chillers system has refrigerant.
The temperature of the ideal discharge superheat is about 10K-15K.
Frequently Asked Questions:
Q.What is low discharge superheat?
When a little amount of air could passes to the system for the reason of stopping the head load entry through the evaporator coils,which occur low discharge superheat.
The low discharge indicates that the quantity of refrigerant liquid or oil present in the compressor.
