CARO Piping Systems and Valves 2

Question 1

What is the purpose of a wet suction riser in an ammonia refrigeration system?

Accepted Answer

To carry a mixture of vapor and liquid upward without trapping liquid at the compressor

Answer

To carry high-pressure liquid refrigerant to the evaporator

Answer

To separate oil from liquid ammonia in vertical piping

Answer

To equalize pressure between vessels at different elevations

Question 2

Which valve type is best suited for throttling or regulating flow in a refrigeration system?

Accepted Answer

Globe valve

Answer

Gate valve

Answer

Check valve

Answer

Ball valve

Question 3

What does 'pipe schedule' refer to in refrigeration piping specifications?

Accepted Answer

The wall thickness of the pipe relative to its nominal diameter

Answer

The maintenance interval for pipe inspections

Answer

The flow velocity specification for the system

Answer

The installation sequence for pipe sections

Question 4

Why is it important to pitch refrigerant suction lines toward the compressor?

Accepted Answer

To ensure oil and liquid refrigerant drain back to the compressor rather than trap in low spots

Answer

To increase refrigerant velocity and capacity

Answer

To reduce pressure drop in the suction line

Answer

To prevent condensation on the outside of insulated piping

Question 5

What is a liquid seal in ammonia refrigeration piping used for?

Accepted Answer

To prevent vapor from migrating from the high-pressure side to the low-pressure side through liquid piping

Answer

To lubricate valve stems in cold service

Answer

To trap oil before it enters the evaporator

Answer

To equalize pressure across the expansion valve

Question 6

When installing ammonia refrigeration piping, copper fittings must NOT be used because:

Accepted Answer

Ammonia reacts with copper to form copper amide, which causes corrosion and system contamination

Answer

Copper is too expensive for industrial applications

Answer

Copper cannot handle the low temperatures of refrigeration systems

Answer

Copper fittings do not meet ASME pressure ratings for refrigerants

Question 7

What is the function of an oil drain valve on an ammonia refrigeration vessel?

Accepted Answer

To drain accumulated oil from the vessel back to the oil pot or drain point

Answer

To release refrigerant pressure before maintenance

Answer

To sample refrigerant quality for purity testing

Answer

To equalize pressure between the vessel and atmosphere