The experience of troubleshooting refrigeration installations on commercial refrigeration and air conditioning used to classify faults in refrigeration eight major families as follows
the first four failures are characterized by an abnormally low BP1 / the failure of the regulator too small (the power of the regulator is insufficient)2 / the fault of lack of support in FF (the refrigerant circuit does not contain enough of FF)3 / failure of the pre-expansion (pre-expansion reaction in the liquid line before the regulator)4 / failure of the evaporator too small (the cooling capacity of the evaporator is insufficient)5 / the fifth failure is characterized by a high BP with a low cooling capacity, it is too small compressor failure, compressor capacity is insufficient
the last three faults are characterized by an abnormally high HP6 / failure of the excess charge (it 's too much FF in the cooling circuit)7 / failure of the condensable (will have one large excess of noncondensable in the circuit)8 / failure of the condenser is too small (the condenser capacity is insufficient)
Whatever the breakdown, it is characterized by a refrigeration low compared to normal power.Failure of the regulator too smallIt is often a row has a bad selection of thermostatic expansion valve (nozzle too small). The regulator does not let enough of FF in the evaporator, the last drop of liquid will appear too very inside of the evaporator, the HS of the vapors leaving the evaporator will be important, the temperature of FF to the compressor suction is high and therefore the discharge of FF also.The compressor can suck more vapor produced in the evaporator, the BP becomes abnormally low. The compressor casing is abnormally hot.The BP has a tendency to decline while the temperature of the fluid to be cooled at the inlet of the evaporator increases, the maximum difference in temperature of the evaporator will be important.The condenser is potentially overkill and since the cooling power generated is low (lack of FF in the evaporator), the excess of FF is found in the condenser, the SR will be very good.
Do not confuse this with the failure of the pre-expansion which is characterized by a temperature difference between the departure of the liquid line and entering the valve.
When the failure of the regulator is located with certainty, it is necessary that the exact cause may be among the following causes:- Poorly chosen regulator- Valve closed too after a poor adjustment- Thermostatic expansion valve being drilled or planned for another FF- Regulator jammed mechanically- Filter entering the valve clogged ...Failure to lack of supportWhen lack of FF in the installation, it also lacks in all organs of the plant, particularly in the major organs.
The evaporator is poorly supplied with FF and impact than the failure of the regulator too small to be observed.
The condenser is overkill but it lacks FF in the condenser also, liquid line will be filled with evil, where the presence of FF gas in the piping, the SR will be virtually zero and bubbles will appear on the sight glass.
The presence of bubbles in the sight glass does not necessarily mean a lack of support in FF, however maque charge always results in the presence of bubbles in the sight glass.
Failure of the pre-expansion
This is a failure following a relaxation of FF on the liquid line before the regulator strictly speaking.For example when the filter-drier is clogged, it opposes the passage of liquid and FF can cause a large pressure drop (depending on the extent of clogging), this pressure drop can be comparable to that created by the "relaxation normal ", then we can find a mixture of liquid and vapor at the outlet of the filter-drier and sight glass is" bubbling ".It follows a lack of FF liquid entering the valve and hence inappropriate power FF of the evaporator with the same symptoms as the failure of the regulator too small. These differ in the two failures fact that there is a temperature difference in the liquid line for the breakdown of the pre-expansion.Failure of the evaporator too small
This failure characterizes all faults causing an abnormal decrease in the capacity of the evaporator. The evaporator produces less vapor that the compressor can aspire, the BP will decrease sharply.Exchanges between the FF liquid in the evaporator and the cooling fluid does not perform properly, the temperature difference of the fluid increases, the fluid is not cooled properly, the FF is not completely vaporized The HS is low and there's risk of stroke liquid, it is as if the regulator becomes overkill.The condenser is potentially overkill since the cooling power generated is low, the SR will be pretty good.
These failures may have two originsA-lack of air flow over the evaporator: the speed of circulation of the fluid (air) is low, the fluid (air) remains in contact with the exchange surfaces, the outlet temperature fluid decreases while the input increases, the temperature difference on the fluid is importantB-evaporator is dirty: the fluid is less well cooled and the temperature difference on the fluid is rather lowThe failure of the evaporator is too small can have several causes (air evaporator):- The tubes and fins of the evaporator are dirty- Air filters are dirty- The evaporator fan belt is broken or patina- Loss of network load of the evaporator airflow is too high- The traffic is bad in the cold- One of the evaporator fan not working- The evaporator fan is running backwards ...It should be noted that the direction of air flow is reversed to an axial type fan when the fan is running backwards, for a centrifugal fan, the flow direction remains unchanged; against by the airflow pressure and ventilation provided fall sharply.Compressor failure too small
This failure includes all the deficiencies which may cause loss of compressor capacity.
For example, when the compressor loses power (a two-cylinder operation, the other being off), everything asse as if the evaporator produces more FF vapor that the compressor can aspire, the BP will rise sharply.The mass flow of traffic in FF is reduced, the cooling capacity will decrease as well.The regulator is overkill and there's risk of slugging, the HS will be low.The amount of FF suction vapor is reduced, the compressor will be less well cooled and housing will be rather hot. The electrical energy consumed by the compressor will decrease.The condenser is overkill, the SR will be good.
- The following list provides an update of some failures of the compressor is too small:- Broken or leaking valve- Broken valve- Compressor is undersized with respect to the evaporator ...Failure of the excess load
The thermostatic expansion valve adjusting the amount of FF in the evaporator, the favorite place for the excess charge is liquid and the bottle to a lesser extent the condenser.In case of excess charge, the liquid level in the bottle will increase and liquid in the condenser, thereby reducing the exchange surface of the condenser.Vapor condensation of FF will go wrong with repercussions on an increase in HP.By the FF against liquid that is in the condenser and liquid in the bottle will stay longer in contact with the coolant (atmosphere), which would assure a good SR.The increase in HP reduces the mass flow of FF sucked by the compressor and consequently a decrease in cooling capacity.The regulator is overkill because of the increase in HP and HS vapors at the outlet of the evaporator will be normal or low.
Note: If an operating pressure (BP or HP) varies in one direction, the other pressure always tends to vary in the same direction except for the small compressor failure or down while the HP BP increases.The increase in HP will lead to higher power consumption and the maximum temperature difference of the condenser will be rather high.It is preferable to testing of condensable not to confuse the failure of the excess charge with the failure of condensable, these two faults having substantially the same symptoms.Failure of condensableThe unwanted gases are condensable (air, nitrogen ...) that are in the refrigerant circuit.They are usually trapped at the top of the bottle and liquid they artificially increase the pressure HP (Dalton's law).The symptoms are the same as those of the breakdown of excess load. Only the test of condensable can differentiate these two faults.
The test is performed condensable as follows:1 - bring all FF liquid in the bottle (or condenser) by an operation such as "Pump Down"2 - forcing the circulation of cooling fluid (for example starting the condenser fan in the case of an air condenser) for some time (1/4 hour)3 - measuring the temperature of cooling fluid (air temperature in the case of an air condenser)4 - compare this temperature indication of the temperature of the manometer HP- If the respective indications of HP pressure gauge and thermometer coincide approximately 2 ° C, there is no condensables in the refrigerant circuit- If the temperature gauge reading is more than 2 ° C warmer than the thermometer, it there's traces of condensable which are even more important that the gap is larger- If the temperature gauge reading is less than 2 ° C warmer than the thermometer, it means that the circuit is loaded with FF, see completely empty
Purging is possible when the bottle includes a liquid trap e upper or creating a drain on the inlet fitting if it is not soldered.Otherwise, empty (recover), to evacuate and recharge the system in FF.Failure of the condenser is too small
This failure characterizes all faults causing an abnormal decrease of the condenser capacity. The condenser can no longer ensure a good cooling vapors FF, HP will increase significantly.The vapor exchanges between the condenser and FF in the cooling fluid does not perform properly, the temperature of the coolant at the outlet of the condenser as well as decreases the temperature difference on the fluid. FF vapors are not fully condensed and the SR is very low or nonexistent. In some cases, even the sight glass can "chill out" while the burden is correct in FF.The increase in HP reduces the cooling capacity and it is as if the regulator becomes overkill, the HS will be normal or low.Because of the high HP, the power consumption of the compressor is greater and the mass flow of FF pumped by the compressor decreases.The compressor suction within FF it may, the BP will increase.These failures may have two origins:- A - the lack of air flow over the condenser: the speed of circulation of the fluid (air) is low, the fluid (air) remains in contact with the exchange surfaces, the outlet temperature the fluid increases, the temperature difference on the fluid is important-B-is dirty the condenser: the temperature of the fluid at the outlet of the condenser is lower than normal, the temperature difference of the fluid will be rather weakThe failure of the condenser is too small can have several causes (air condenser):- Tubes and condenser fins are dirty- The location of the condenser is a misnomer- The condenser fan belt is broken or patina- Loss of network load of the evaporator airflow is too high- Will have one recycling of hot air over the condenser- One of the condenser fans not working- The evaporator fan is running backwards ...Synthetic scheme refrigerated failures
the first four failures are characterized by an abnormally low BP1 / the failure of the regulator too small (the power of the regulator is insufficient)2 / the fault of lack of support in FF (the refrigerant circuit does not contain enough of FF)3 / failure of the pre-expansion (pre-expansion reaction in the liquid line before the regulator)4 / failure of the evaporator too small (the cooling capacity of the evaporator is insufficient)5 / the fifth failure is characterized by a high BP with a low cooling capacity, it is too small compressor failure, compressor capacity is insufficient
the last three faults are characterized by an abnormally high HP6 / failure of the excess charge (it 's too much FF in the cooling circuit)7 / failure of the condensable (will have one large excess of noncondensable in the circuit)8 / failure of the condenser is too small (the condenser capacity is insufficient)
Whatever the breakdown, it is characterized by a refrigeration low compared to normal power.Failure of the regulator too smallIt is often a row has a bad selection of thermostatic expansion valve (nozzle too small). The regulator does not let enough of FF in the evaporator, the last drop of liquid will appear too very inside of the evaporator, the HS of the vapors leaving the evaporator will be important, the temperature of FF to the compressor suction is high and therefore the discharge of FF also.The compressor can suck more vapor produced in the evaporator, the BP becomes abnormally low. The compressor casing is abnormally hot.The BP has a tendency to decline while the temperature of the fluid to be cooled at the inlet of the evaporator increases, the maximum difference in temperature of the evaporator will be important.The condenser is potentially overkill and since the cooling power generated is low (lack of FF in the evaporator), the excess of FF is found in the condenser, the SR will be very good.
Do not confuse this with the failure of the pre-expansion which is characterized by a temperature difference between the departure of the liquid line and entering the valve.
When the failure of the regulator is located with certainty, it is necessary that the exact cause may be among the following causes:- Poorly chosen regulator- Valve closed too after a poor adjustment- Thermostatic expansion valve being drilled or planned for another FF- Regulator jammed mechanically- Filter entering the valve clogged ...Failure to lack of supportWhen lack of FF in the installation, it also lacks in all organs of the plant, particularly in the major organs.
The evaporator is poorly supplied with FF and impact than the failure of the regulator too small to be observed.
The condenser is overkill but it lacks FF in the condenser also, liquid line will be filled with evil, where the presence of FF gas in the piping, the SR will be virtually zero and bubbles will appear on the sight glass.
The presence of bubbles in the sight glass does not necessarily mean a lack of support in FF, however maque charge always results in the presence of bubbles in the sight glass.
Failure of the pre-expansion
This is a failure following a relaxation of FF on the liquid line before the regulator strictly speaking.For example when the filter-drier is clogged, it opposes the passage of liquid and FF can cause a large pressure drop (depending on the extent of clogging), this pressure drop can be comparable to that created by the "relaxation normal ", then we can find a mixture of liquid and vapor at the outlet of the filter-drier and sight glass is" bubbling ".It follows a lack of FF liquid entering the valve and hence inappropriate power FF of the evaporator with the same symptoms as the failure of the regulator too small. These differ in the two failures fact that there is a temperature difference in the liquid line for the breakdown of the pre-expansion.Failure of the evaporator too small
This failure characterizes all faults causing an abnormal decrease in the capacity of the evaporator. The evaporator produces less vapor that the compressor can aspire, the BP will decrease sharply.Exchanges between the FF liquid in the evaporator and the cooling fluid does not perform properly, the temperature difference of the fluid increases, the fluid is not cooled properly, the FF is not completely vaporized The HS is low and there's risk of stroke liquid, it is as if the regulator becomes overkill.The condenser is potentially overkill since the cooling power generated is low, the SR will be pretty good.
These failures may have two originsA-lack of air flow over the evaporator: the speed of circulation of the fluid (air) is low, the fluid (air) remains in contact with the exchange surfaces, the outlet temperature fluid decreases while the input increases, the temperature difference on the fluid is importantB-evaporator is dirty: the fluid is less well cooled and the temperature difference on the fluid is rather lowThe failure of the evaporator is too small can have several causes (air evaporator):- The tubes and fins of the evaporator are dirty- Air filters are dirty- The evaporator fan belt is broken or patina- Loss of network load of the evaporator airflow is too high- The traffic is bad in the cold- One of the evaporator fan not working- The evaporator fan is running backwards ...It should be noted that the direction of air flow is reversed to an axial type fan when the fan is running backwards, for a centrifugal fan, the flow direction remains unchanged; against by the airflow pressure and ventilation provided fall sharply.Compressor failure too small
This failure includes all the deficiencies which may cause loss of compressor capacity.
For example, when the compressor loses power (a two-cylinder operation, the other being off), everything asse as if the evaporator produces more FF vapor that the compressor can aspire, the BP will rise sharply.The mass flow of traffic in FF is reduced, the cooling capacity will decrease as well.The regulator is overkill and there's risk of slugging, the HS will be low.The amount of FF suction vapor is reduced, the compressor will be less well cooled and housing will be rather hot. The electrical energy consumed by the compressor will decrease.The condenser is overkill, the SR will be good.
- The following list provides an update of some failures of the compressor is too small:- Broken or leaking valve- Broken valve- Compressor is undersized with respect to the evaporator ...Failure of the excess load
The thermostatic expansion valve adjusting the amount of FF in the evaporator, the favorite place for the excess charge is liquid and the bottle to a lesser extent the condenser.In case of excess charge, the liquid level in the bottle will increase and liquid in the condenser, thereby reducing the exchange surface of the condenser.Vapor condensation of FF will go wrong with repercussions on an increase in HP.By the FF against liquid that is in the condenser and liquid in the bottle will stay longer in contact with the coolant (atmosphere), which would assure a good SR.The increase in HP reduces the mass flow of FF sucked by the compressor and consequently a decrease in cooling capacity.The regulator is overkill because of the increase in HP and HS vapors at the outlet of the evaporator will be normal or low.
Note: If an operating pressure (BP or HP) varies in one direction, the other pressure always tends to vary in the same direction except for the small compressor failure or down while the HP BP increases.The increase in HP will lead to higher power consumption and the maximum temperature difference of the condenser will be rather high.It is preferable to testing of condensable not to confuse the failure of the excess charge with the failure of condensable, these two faults having substantially the same symptoms.Failure of condensableThe unwanted gases are condensable (air, nitrogen ...) that are in the refrigerant circuit.They are usually trapped at the top of the bottle and liquid they artificially increase the pressure HP (Dalton's law).The symptoms are the same as those of the breakdown of excess load. Only the test of condensable can differentiate these two faults.
The test is performed condensable as follows:1 - bring all FF liquid in the bottle (or condenser) by an operation such as "Pump Down"2 - forcing the circulation of cooling fluid (for example starting the condenser fan in the case of an air condenser) for some time (1/4 hour)3 - measuring the temperature of cooling fluid (air temperature in the case of an air condenser)4 - compare this temperature indication of the temperature of the manometer HP- If the respective indications of HP pressure gauge and thermometer coincide approximately 2 ° C, there is no condensables in the refrigerant circuit- If the temperature gauge reading is more than 2 ° C warmer than the thermometer, it there's traces of condensable which are even more important that the gap is larger- If the temperature gauge reading is less than 2 ° C warmer than the thermometer, it means that the circuit is loaded with FF, see completely empty
Purging is possible when the bottle includes a liquid trap e upper or creating a drain on the inlet fitting if it is not soldered.Otherwise, empty (recover), to evacuate and recharge the system in FF.Failure of the condenser is too small
This failure characterizes all faults causing an abnormal decrease of the condenser capacity. The condenser can no longer ensure a good cooling vapors FF, HP will increase significantly.The vapor exchanges between the condenser and FF in the cooling fluid does not perform properly, the temperature of the coolant at the outlet of the condenser as well as decreases the temperature difference on the fluid. FF vapors are not fully condensed and the SR is very low or nonexistent. In some cases, even the sight glass can "chill out" while the burden is correct in FF.The increase in HP reduces the cooling capacity and it is as if the regulator becomes overkill, the HS will be normal or low.Because of the high HP, the power consumption of the compressor is greater and the mass flow of FF pumped by the compressor decreases.The compressor suction within FF it may, the BP will increase.These failures may have two origins:- A - the lack of air flow over the condenser: the speed of circulation of the fluid (air) is low, the fluid (air) remains in contact with the exchange surfaces, the outlet temperature the fluid increases, the temperature difference on the fluid is important-B-is dirty the condenser: the temperature of the fluid at the outlet of the condenser is lower than normal, the temperature difference of the fluid will be rather weakThe failure of the condenser is too small can have several causes (air condenser):- Tubes and condenser fins are dirty- The location of the condenser is a misnomer- The condenser fan belt is broken or patina- Loss of network load of the evaporator airflow is too high- Will have one recycling of hot air over the condenser- One of the condenser fans not working- The evaporator fan is running backwards ...Synthetic scheme refrigerated failures
