When a new system has been assembled, the first thing to do is?
Pressurize the system with an inert gas & leak check.
After installation of a
... [Show More] field-piped R-410A split heat pulp, the unit should first be?
Pressurized with nitrogen then leak checked.
The EPA regulations require that any appliances containing more than 50 pounds of refrigerant (except for commercial & industrial process refrigeration) must be repaired when the leak rate exceeds _________ of the charge per year?
15%
R-410A requires recovery tanks rated for at least?
400 psig
After refrigerant liquid has been recovered from a system, any remaining vapor is?
Condensed by the recovery system.
Your recovery/recycling machine has R-502 refrigerant in it. You now have to recover refrigerant from a unit with R-22. What must be done before the R-22 refrigerant can be recovered/recycled?
Recover as much R-502 from the recovery unit as possible, change filter, & evacuate.
In a refrigeration system with a TXV (or other type of throttling device), the component directly following the condenser is the?
Receiver
When charging an R-410A system that uses a water-cooled condenser, you must first charge with vapor to a pressure of at least________, before switching to liquid charging.
120 psig
Recovered refrigerant may contain what?
1.) Acids
2.) Moisture
3.) Oils
Your recovery/recycling machine has R-22 refrigerant in it. You now have to recover refrigerant from a unit with R-410A. What must be done before your recovery unit can be used to recover R-410A?
1.) The recovery unit must be EPA certified for use with R-410A.
2.) The recovery tank must be designed for the pressure of R-410A.
3.) The filter & lubricant in the recovery unit must be changed, & the recovery unit evacuated.
To recover liquid refrigerant, you must connect one hose to the?
Liquid Line.
The proper charging method for blended (non-azeotropic) refrigerants (400 Series) is to use a remove the charge from the cylinder as a?
Liquid
Before using a recovery unit to remove a charge, what steps should be taken?
1.) Check service valve positions.
2.) Check the oil level in the recovery unit.
3.) Evacuate recovery unit & recovery tank.
On refrigeration units that use an open compressor; the ________ is most likely to leak if the unit is not used for several months.
The rotating shaft seal.
Noncondensables in a system cause?
Higher discharge pressure.
Heat Pumps that use R-410A should be leak checked with?
Pressurized Nitrogen.
A reciprocating compressor should not be energized when?
The discharge service valve is closed.
In a refrigeration system, the component directly following the evaporator is the?
Accumulator.
Manifold gauge set hoses should have self-sealing connectors or hand valves to?
Minimize the release of refrigerant when the hoses are connected & disconnected.
The EPA regulations require that leaking commercial or industrial process refrigeration equipment must be repaired when the leak rate exceeds _____ of the charge per year.
35%
Moisture is removed from a system by?
Using a filter drier.
Oil foaming usually occurs in the?
Compressor
R-410A is different from other ASHRAE 400 series non-azeotropic blends because?
R-410A behaves as a near azeotropic refrigerant, & can be topped off.
With an air-cooled condenser on the roof of a building & the evaporator on the first floor, recovery should first occur?
From the liquid line entering the evaporator.
A deep vacuum is usually measured in?
Microns.
Heat Pumps that use R-134A should be leak checked with?
Pressurized Nitrogen.
During the evacuation of a system that contains large amounts of moisture it may be necessary to increase pressure in the system with ________, to counteract the freezing of the moisture.
Nitrogen.
When under a deep vacuum, the motor winding of a hermetic refrigeration compressor?
Will be damaged if energized.
When using recovery or recycling equipment that was manufactured AFTER November 15, 1993: you must evacuate a system containing MORE than 200 pounds of CFC-12 to _______ before making a major repair.
15 inches Hg vacuum
When inspecting a system for leaks, you should look for?
Traces of oil.
Refrigerant leaves the receiver of a system as a?
High pressure liquid.
A compressor heater is used to?
Reduce the amount of refrigerant in the lubricating oil.
The evaporation temperature of R-134a at 0 psig is?
-15F
Dry nitrogen should be used to break the first vacuum when dehydrating by the double evacuation method. However, it?
Can be dangerous if not used with a pressure regulator.
When servicing a 60-ton packaged rooftop unit. The easiest way to check the type of refrigerant is uses is to?
Look at the unit nameplate.
R-410A requires certified recovery & recycling machines rated for at least?
400 psig
When using recovery or recycling equipment that was manufactured BEFORE November 15, 1993, technicians must evacuate a unit that has a normal charge of 10 pounds of CFC-500 to _______ before disposing of the system.
4 inches of Hg vacuum.
An oil sample should be taken when _________.
The compressor has burned-out.
You are going to service a newer residential split system air conditioner. You would expect to find the system charged with what refrigerant?
R-410A
A system can be evacuated to only atmospheric pressure when?
Leaks in the appliance make evacuation to the prescribed level unattainable.
When evacuating a system, the use of a large vacuum pump could?
Cause trapped water to freeze.
On a high-pressure system___________ is an indicator of a possible leak.
Excessive superheat.
A routine maintenance task which must be performed on refrigerant recycling machines is to?
Change filter & compressor oil (if any).
To change the compressor on a system containing 40 pounds of R-500, using a recycling machine that was manufactured AFTER November 15, 1993, you must isolate the compressor then?
Evacuate the isolated section of the system to 10 inches of vacuum & hold. If system pressure does not rise, remove the compressor.
The backseating of a suction shutoff valve will close the?
Gauge Port.
The primary water source for cooling the condenser of a water-cooled recovery unit is?
Local municipal water supply.
Which statement is NOT true about recycling & recovery equipment manufactured after November 15, 1993?
It must have an oil separator.
When using recovery or recycling equipment that was manufactured AFTER November 15, 1993, you must evacuate a system containing MORE than 200 pounds of CFC-12 to _______ before making a major repair.
15 inches of Hg vacuum.
Never use oxygen or compressed air to leak-check hardware because R-410A can?
Explode when mixed with air or oxygen.
When a unit is opened for servicing, the _______ should always be replaced.
Filter-drier.
The evaporation temperature of R-134A at 0 psig is?
-15F
Refrigerant should be removed from the condenser outlet if the?
Condenser is below the receiver.
In a refrigeration system, the component directly following the evaporator is the?
Accumulator.
Before using a recovery unit to remove a charge, what steps should be taken?
A.) Check service valve positions
B.) Check the oil level in the recovery tank.
C.) Evacuate recovery unit & recovery tank.
After reaching the required vacuum on a system you must?
Wait to see if the pressure rises, indicating that there is still refrigerant in liquid form or refrigerant trapped in the oil.
Which component is NOT part of the low side of the system?
Receiver.
Refrigerant leaves the receiver of a system as a?
High pressure liquid.
Use ___________ to remove ice from a sight glass.
An alcohol spray.
Soap bubble testing is used to?
Pinpoint refrigerant leaks.
The refrigerant pressure inside an R-12 unit which is at room temperature (72F) & not operating is?
Approximately 74 psig.
R-410A requires a high pressure manifold gauge & hose set. They must have a?
4000 psig burst pressure & 800 psig working pressure.
The refrigerant pressure inside an R-410A unit which is at room temperature (72F) & not operating is?
Approximately 210 psig.
A recovery machine that uses a hermetic compressor will overheat when drawing a deep vacuum because?
The motor needs a flow of refrigerant through the compressor to provide motor cooling.
On refrigeration units that use an open compressor; the _______ is most likely to leak if the unit is not used for several months.
The rotating shaft seal.
Heat pumps that have been retrofitted from R-22 to R-407C should be leak checked with?
Pressurized nitrogen.
When a refrigerant trace gas becomes absolutely necessary, which of the available refrigerants should be used to identify a leak?
HCFC-22
When charging an R-12 refrigeration system that uses a water-cooled condenser, you must first charge with vapor to a pressure of at least ________, before switching to liquid charging.
35 psig.
The vacuum pump used to evacuate a system should be capable of pulling a vacuum of?
500 microns.
While R-410A is a high pressure refrigerant, it can be stored in the back of your service van as long as?
The temperature inside the vehicle does not exceed 125F. This is the same guidance given for R-22 & other common refrigerants.
You are going to service an older residential split system air conditioner. You would expect to find the system charged with which refrigerant?
R-22 [Show Less]