EPA Type III

A typical setting for the high-pressure cut-out control on a recovery unit used for evacuating refrigerant from a low-pressure chiller is

10 psig

A charged low pressure refrigeration system can be efficiently leak-checked by

The existence of air in a low pressure system causes

Which safety precaution should be adhered to for low pressure systems?

Do not siphon refrigerant by mouth .. dummy.

Avoid spilling liquid refrigerant on your skin.

Use gloves and safety goggles when working with liquid refrigerant.

All of the above

Refrigerant-11 (R-11) at 14.7 psia, will boil at about

74.5 F

When there is excessive moisture collecting in the purge unit of a low pressure refrigeration system, this indicates that

the condenser or chiller barrel tubes are leaking.

ASHRAE Standard 15-1994 requires equipment room refrigerant sensors for what safety group classification?

A1

B2

A2

All refrigerant safety groups

After reaching the required recovery vacuum on a chiller, you should

wait for at least a few minutes to see if the system pressure rises, indicating there is still refrigerant in liquid form or in the oil.

A hydrostatic tube test kit is used to

determine if a tube leaks.

When charging a chiller, refrigerant vapor is introduced into the system before charging with liquid refrigerant. This is because

liquid charged into a deep vacuum will cause the refrigerant to boil and may lower temperatures enough to freeze the water in the tubes.

When evacuating a system, the use of too large a vacuum pump can cause

trapped water to freeze.

On a low pressure chiller with an open-type compressor, the _________ is/are very susceptible to leaks.

shaft seal

What steps may be taken to prevent air accumulation into an idle low-pressure refrigeration system?

System pressure should be maintained slightly above atmospheric pressure.

Commercial and industrial process refrigeration systems must be repaired when the leak rate exceeds ______ percent of the charge per year.

30 percent

When recovering vapor from a low pressure refrigeration system,

the system water pumps, the recovery compressor, and the recovery condenser water should all be on.

Where does refrigerant go after it leaves the purge unit of a low pressure centrifugal system?

The evaporator

The purge unit takes its suction from the

top of the condenser

Which of the following repairs would ALWAYS be considered a “major” repair unde EPA’s regulations?

Replacement of an evaporator coil.

Charging liquid refrigerant into a refrigeration system when it is under a 29-inch Hg vacuum can cause the

system water to freeze.

According to the EPA there is approximately ________ of refrigerant vapor left in an average 350 ton R-11 chiller at 0 psig pressure once all the R-11 liquid has been removed.

100 lbs

An oil sample should be taken when

there has been a compressor burnout.

Both CFC-11 and HCFC-123 chillers require purge units because

the system operates below atmospheric pressure.

Refrigerant recovery typically starts with __________ because it is faster.

liquid recovery

Under EPA regulations, _________ is used to pressurize a low-pressure chiller for the purpose of opening the system for a non-major repair.

warming the refrigerant

The primary water source for a recovery unit condensing coil is

the local municipal water supply.

Which statement is NOT true of recycling and recovery equipment manufactured after November 15 1993?

It must be able to handle more than one refrigerant.

A system does not have to be evacuated all the way to the required level when

leaks in the appliance make evacuation to the prescribed level impossible.

Which action listed below is the proper method to reduce refrigerant loss from a purge unit on a CFC-11 chiller?

Leak-test and repair the chiller.

Identify the pressure corresponding to 32F for R-123:

20 inches of Hg vacuum.

What precaution should be taken prior to recovering refrigerant from a chiller suspected of having tube leaks?

Drain the water sides of the evaporator and condenser.

Pressure relief valves must never be

installed in series.

If you are going to be removing oil from a low-pressure system, you should heat the oil because

less refrigerant will be contained in the oil at high temperatures.

After recovering the liquid refrigerant you must

recover the refrigerant vapor.

EPA regulations require that any appliances containing more than 50 pounds of refrigerant, except for commercial and industrial process refrigeration, must be repaired when the leak-rate exceeds ______ of the charge per year.

10 percent

If you are using a recovery machine manufactured BEFORE November 15 1993, you must evacuate any low-pressure appliance to ______ before making a major repair.

25 inches of Hg vacuum

On low-pressure chillers, moisture typically enters the refrigerant system through

air leaks from areas with gaskets or fittings.

Refrigerant-11 at a pressure of 17 inches Hg vacuum has a saturation temperature of

35 F

The lowest access point on a low-pressure centrifugal air-conditioning unit is the

evaporator charging valve.

A rupture disc on a recovery vessel for low-pressure refrigerants relieves at

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.

2.5 mm Hg

During chiller evacuation, water is circulated to

prevent freezing of the water.

When charging an R-410a water chiller, you must first charge with vapor to a pressure of at least  ______ before switching to liquid charging.

120 psig

If you leak test a low-pressure chiller with nitrogen in excess of 10 psig you could cause the ______ to fail.

rupture disc

ASHRAE Standard 15-1994 requires that each machinery room must activate an alarm and mechanical ventilation before refrigerant concentrations exceed

the TLV - TWA (Threshold Limit Value - Time Weighted Average)

Which repair WOULD NOT fall under the EPA definition for major maintenance, service, or repair?

Replacing an oil filter.

Refrigerant is added to a centrifugal machine through the

evaporator charging valve.

What is meant by the term “high efficiency purge unit”?

Those purge units which discharge a low percentage of refrigerant with the air they remove.

The primary purpose of a purge unit on a CFC-11 chiller is to

remove noncondensables from the system.

If you are using a recovery machine manufactured AFTER November 15 1993, you must evacuate any low pressure appliance to ______ before making a major repair.

25 inches of Hg vacuum

During the evacuation of a system containing large amounts of moisture, you can prevent freezing of this moisture by increasing the pressure with

nitrogen gas