On low pressure chillers, moisture typically enters the refrigerant system through - Answer- air leaks from areas with gaskets or fittings
The maximum test pressure for leak testing a low pressure centrifugal is: - An
...
On low pressure chillers, moisture typically enters the refrigerant system through - Answer- air leaks from areas with gaskets or fittings
The maximum test pressure for leak testing a low pressure centrifugal is: - Answer- 10 psig
Leak test and repair the chiller to reduce refrigerant loss from a pruge unit on CFC-11 chiller - Answer- ...
A hydrostatic tube test kit is used to: - Answer- determine if a tube leaks
Commercial and industrial process refrigeration systems must be repaired when the leak rate exceeds ____ of the charge per year. - Answer- 35%
Refrigerant recovery typically start with liquid recovery it is faster. - Answer- ...
A rupture disc on a recovery vessel for a low pressure refrigerants relieves at: - Answer- 15 psig
According to ASHRAE Guideline 3-1996, if the pressure in a system rises from 1 mm Hg to a level above ____ during a standing vacuum test, the system should be checked for leaks. - Answer- 2.5 mm Hg
The primary water source for a recovery unit condensing coil is _____. - Answer- local municipal water supply
When recharging a refrigeration system with R-11, what vaporpressure is necessary in the shells before changing with liquid? - Answer- 16.9" Hg vacuum
After recovering the liquid refrigerant you must: - Answer- recover the vapor refrigerant
According to the EPA there is approximately _____ refrigerant vapor left in an average 350 ton R-11 chiller at 0 psig pressure once all the R-11 liquid has been removed. - Answer- 100 pounds
Charging refrigerant liquid into a refrigeration system when it is under a 29 inch Hg vacuum can cause the: - Answer- system water to freeze
A system does not have to be evacuated all the way to the required level when: - Answer- leaks in the appliance make evacuation to the prescribed level unattainable
Which of the foloowing repairs would ALWAYS be considered "major" under EPA's - Answer- replacement of evaporator coil
Under EPA's regulation's _______ is used to pressurize a low pressure chiller for the purpose of opening the system for a non major repair? - Answer- warming the refrigerant
If you are using a recovery machine manufactored AFTER 11-15-93 you must evacuate an low pressure appliance to _______ before making a major repair. - Answer- 25 mm of Hg absolute
After reaching the required recovery vacuum on a chiller, you should - Answer- Wait for at least a few minutes to see if the system pressure rises, indicating that there is till refrigerant in a liquid form or in the oil
The pressure corresponding to 32 F for R-123 - Answer- 20 inches of HG vacuum
When evacuating a system the use of too large a vacuum pump can cause? - Answer- trapped water to freeze
Refrigerant-11 at a pressure of 17 inches HG vacuum has a saturation temperature of: - Answer- 35F
During the evacuation of a system containing large amounts of moisture you can prevent freezing of this moisture by increasing the pressure with______gas - Answer- nitrogen
ASHRAE standard 15-1994 requires that each machinery room must activate an alarm and mechanical ventilation beofre refrigerant concentrations exceed: - Answer- the threshold limit valve and time weighted average
The typical design burst pressure for a rupture disk on a low pressure centrifugal air-conditioning system is set at_______ - Answer- 15 psi
Heat pumps that have been retrofitted from R22 to R407C should be leak checked with: - Answer- pressurized nitrogen
When a new system has been assembled, the first thing to do is: - Answer- pressurize the system with inert gas and leak check
EPA regulations require that leaking commercial or industrial process refrigeration equipment must be repaired when the leak rate exceeds______ of the charge per year. - Answer- 35%
Prior to replacing the condenser coil in a high pressure system, the refrigerant was recovered and stored in a refillable container. The refrigerant: - Answer- can probably be charged back into the system
R-410A requires recovery tanks rated for at least: - Answer- 400 psig
to recover liquid refrigerant you must connect one hose to the - Answer- liquid line
The primary water source for cooling the condenser of a water-cooled recovery unit is: - Answer- local municipal water supply
After refrigerant liquid has been recovered from a system, any remaining vapor is: - Answer- condensed by the recovery system
the recovery of refrigerant from a system as a vapor only will minimize the loss of: - Answer- oil
When using recovery or recycling equipment that was made after 11-15-93 you must evacute a system containing MORE than 200 pounds of CFC-12 to ________ before making a major repair. - Answer- 15 inches of HG vacuum
With an air-cooled condenser on the roof of a building and the evaporator on the first floor, recovery should first occur: - Answer- from the liquid line entering the evaporator
When using recovery or recycling equipment that was made BEFORE 11-15-93 technicians must evacuate a unit that has a normal charge of 10 pounds of CFC-500 to _____ before disposing of the system. - Answer- 4 inches of HG vacuum
A system can be evacuated to only atmospheric pressure when: - Answer- leaks in the appliance make the evacuation to the prescribed level unattainable
To change the compressor on a system cantaining 40 pounds R-500 using a recycling machine that was manufactured AFTER 11-15-93 you must isolate the compressor then: - Answer- evacuate the isolated section of the system to 10 inches of vacuum and hold. If the system pressure does not rise, remove the compressor.
Recycling and recovery equipment maufactured after 11-15-93 does not need an oil separator - Answer- ...
To change the compressor on a system containing R-410A, you must isolate the compressor then: - Answer- Evacuate the isolated section of the system to atmospheric pressure and hold. If system pressure does not rise, remove the compressor.
System- dependent recovery equipment CANNOT be used when: - Answer- the appliance contains over 15 pounds of refrigerant
Moisture is removed a system by: - Answer- using a filter drier
When a unit is opened for servicing the ______ should always be replaced - Answer- filter drier
The backseating of a suction shutoff valvee will close the: - Answer- guage port
When charging an R-12 refrigeration system that uses a water cooled condensor, you must first charge with vapor to a pressure of at least _____ , before switching to a liquid charging. - Answer- 35 psig
A compressor heater is used to: - Answer- reduce the amount of refrigerant in the lubricating oil
While R-410A is a high pressure refrigerant, it can be stored in the back of your service van as long as: - Answer- the temperature inside the vehicle does not exceed 125 degrees F. This is the same guidance given for R-22 and other common refrigerants.
For what refrigerant is an equipment room refrigerant monitor required under ASHRAE standard 15? - Answer- R-123
A reciprocating compressor should not be energized if the - Answer- discharge service valve has closed
What factor affects the speed of evacuation? - Answer- the size of the equipment
the ambient temperature
the amount of moisture in the system
The evacuation of a system is a method of: - Answer- dehydration
When moisrture exists in an operating system which is likely to occur? - Answer- Acid will form
The over-evacuation of a system: - Answer- does not occur
A system is considered dehydrated when: - Answer- the vacuum indicator shows you have reached & held the required finished vacuum
When evacuating a system the hoses should be: - Answer- equal to or larger than the vacuum pump inlet connection
When evacuating a system the hoses should be: - Answer- short in length & as large in diameter as possible
When operating refrigerant recovery or recycling equipment the following precautions should be taken - Answer- safety glasses & gloves along with following equipment safety precautions
The color code for refrigerant recovery cylinders is - Answer- yellow tops with grey bodies
Never use oxygen or compressed air to pressurize a sytem because: - Answer- when mixed with compresser oil or some refrigerants it could explode
what type of refrigerant is clorine free - Answer- HFC's
When using any solvent, chemical, cleaner, chemical or refrigerant you should review - Answer- MSDS (data sheets)
Refrigerant vapors or mist should not be inhaled because - Answer- they may cause heart irregularities & or unconsciousness
When using recovery unit the fill level of the recovery tank can be controlled by - Answer- mechanical float switch
electronic shutt-off device
weight
HCFC - Answer- R-22
R-123
R-124
it is necessary to place a refrigerant label on: - Answer- a frigerant cylinder that is being returned for reclaiming
DOT requires youdo this when transporting cylinders - Answer- attach DOT
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