313A Refrigerant Handling 2

Question 1

What is the purpose of evacuating a refrigeration system and what vacuum level should be achieved?

Accepted Answer

Evacuation removes air and moisture by pulling a deep vacuum; target is 500 microns (0.5 mm Hg) or lower for systems using hygroscopic refrigerants like R-410A

Answer

Evacuation removes excess refrigerant; target is 0 psig

Answer

Evacuation removes oil; target is atmospheric pressure

Answer

Evacuation is optional if the system is new

Question 2

What is the proper method for charging R-410A refrigerant into a system?

Accepted Answer

Charge as a liquid through the high side (liquid line) or through the suction side with a metering device to prevent liquid slugging, because R-410A is a near-azeotropic blend

Answer

Charge as a gas through the suction side only

Answer

Charge as a gas through the discharge side

Answer

Charge by weight through the compressor oil port

Question 3

What is a triple evacuation and when is it recommended?

Accepted Answer

Three cycles of pulling a vacuum then breaking with dry nitrogen, followed by a final deep vacuum; recommended for systems with significant moisture contamination

Answer

Evacuating the system three times in a row

Answer

Three different vacuum pumps used simultaneously

Answer

Evacuating the high side, low side, and oil sump separately

Question 4

What are the dangers of mixing different refrigerants in a system?

Accepted Answer

It can create unpredictable pressures, reduce capacity, damage the compressor, void equipment warranties, and create unsafe operating conditions

Answer

It only causes a slight reduction in efficiency

Answer

Different refrigerants naturally separate and cause no issues

Answer

Mixing is recommended for better performance

Question 5

What is a standing pressure test and what does it verify?

Accepted Answer

Pressurizing the system with dry nitrogen to a specified pressure and monitoring for a drop over time to verify the system has no leaks

Answer

A test of the compressor's discharge pressure during operation

Answer

A test of the water pressure in cooling towers

Answer

A measurement of oil pressure in the compressor

Question 6

Under Canada's Environmental Protection Act, what is the maximum allowable leak rate for commercial refrigeration systems before repairs are required?

Accepted Answer

Systems containing more than a threshold amount of refrigerant must repair leaks within a specified timeframe, and annual leak rates exceeding approximately 10-20% (depending on province) require mandatory reporting and repair

Answer

There is no regulated limit

Answer

50% per year is acceptable

Answer

Only total loss requires reporting