HVAC Type 3

In low-pressure systems, what will leaks in gaskets or fittings cause?

• Loss of oil from the compressor

• Air and moisture to enter the system

• Refrigerant to solidify in the condenser

• Immediate tripping of all safety controls

What is a purge unit?

• A device that meters liquid refrigerant into the evaporator

• A pump that circulates condenser water

• A unit that removes non‑condensables that leak into a low‑pressure chiller system

• A filter drier used to remove moisture from refrigerant lines

Where does a purge unit get its suction from?

• The bottom of the evaporator

• A connection on top of the condenser where most non‑condensables accumulate

• The oil sump of the compressor

• The discharge line after the compressor

Once the air is separated from the refrigerant, where does the purge unit send the refrigerant to?

• The condenser

• The evaporator

• The receiver

• The liquid line filter drier

What is a sign that the system might be leaking?

• Low condenser water temperature

• Excessive running of a purge system

• High evaporator approach temperature

• Frequent cycling of the thermostat

What type of kit is used to determine if a tube is leaking?

• Dye injection kit

• Hydrostatic tube test kit

• Ultrasonic acoustic kit

• Halide torch kit

If you are leak testing a low‑pressure centrifugal chiller with nitrogen, what is the maximum test pressure?

• 5 psig

• 10 psig

• 25 psig

• 50 psig

What is the most efficient way to leak check a low‑pressure refrigeration machine?

• Pressurize with nitrogen to a high pressure

• Use soap bubbles on every joint

• Adding heat with circulated hot water or heating blankets

• Rely on an electronic leak detector alone

How do you prevent air accumulation in an idled low‑pressure refrigeration system?

• Isolate and evacuate the condenser only

• Maintain system pressure slightly above atmospheric pressure

• Shut all valves and power down the purge unit

• Flood the evaporator with liquid refrigerant

According to ASHRAE Guideline 3, the system should be checked for leaks if, during a standard vacuum test, the pressure in a system rises from ___ mm Hg to a level above ___ mm Hg.

• From 1 mm Hg to above 2.5 mm Hg

• From 2.5 mm Hg to above 5 mm Hg

• From 10 mm Hg to above 20 mm Hg

• From 0.5 mm Hg to above 1.0 mm Hg