313A Piping, Brazing & Leak Detection 2

Question 1

Which refrigerant leak detection method offers the highest sensitivity, capable of detecting leaks as small as 0.1 oz per year?

Accepted Answer

Electronic refrigerant leak detector

Answer

Bubble solution (soap) test

Answer

UV fluorescent dye and black light

Answer

Nitrogen standing pressure test

Question 2

Under Canadian federal refrigerant regulations, technicians must repair leaks in systems with a refrigerant charge above what threshold within 30 days of detection?

Accepted Answer

Systems with a charge above 3 kg

Answer

Any system regardless of charge size

Answer

Systems with a charge above 100 kg

Answer

Only R-22 and other HCFC systems

Question 3

When pressure testing a refrigerant system, dry nitrogen is preferred over refrigerant because:

Accepted Answer

Nitrogen is inert, non-toxic, non-flammable, and leaves no residue in the system

Answer

Nitrogen is less expensive and always available at the jobsite

Answer

Nitrogen can reach higher test pressures than most refrigerants

Answer

Nitrogen dissolves in refrigeration oil, making leak paths more visible

Question 4

UV dye leak detection requires which additional piece of equipment to be effective?

Accepted Answer

A UV (black light) lamp and UV-filtering safety glasses

Answer

An infrared thermal camera

Answer

A digital manifold gauge set to confirm suction side leaks

Answer

A refrigerant identifier to confirm dye compatibility

Question 5

A nitrogen standing pressure test is held at 200 psig. After 60 minutes the gauge reads 192 psig with no change in ambient temperature. What is the most likely explanation?

Accepted Answer

A leak exists somewhere in the system

Answer

Normal absorption of nitrogen into the refrigeration oil

Answer

Nitrogen is condensing inside the tubing at operating temperature

Answer

The Bourdon gauge is reading low due to calibration drift

Question 6

Which type of electronic leak detector is best suited for detecting leaks of HFO refrigerants such as R-1234yf?

Accepted Answer

Infrared (IR) sensor detector

Answer

Heated diode (halide) detector

Answer

Heated pentode detector

Answer

Ultrasonic acoustic detector

Question 7

After repairing a refrigerant system leak, what two steps are mandatory before recharging with refrigerant?

Accepted Answer

Perform a leak test, then evacuate the system to deep vacuum

Answer

Flush the system with dry nitrogen, then recharge immediately

Answer

Pressure test with refrigerant, then add a drier and recharge

Answer

Run the compressor briefly on nitrogen, then recharge to nameplate weight