2 Safe Service of Low-Pressure Chillers Free Online FlashCards

What can a leak draw into a low-pressure chiller?

A leak in a below-atmospheric section can draw air and moisture into the system.

What can unusually frequent purging indicate?

Unusually frequent or prolonged purging can signal air infiltration, but it does not locate the leak.

Which sites should be inspected for refrigerant leaks?

Inspect likely sites such as gaskets, fittings, shaft seals, and heat-exchanger tubes with a suitable detector or approved locating method.

How should pressure generally be raised for a charged-system leak check?

Controlled heating, such as circulated warm water or a built-in heating device, is generally preferred. Use nitrogen only when the applicable procedure allows it.

What limits must leak-test pressure stay within?

Never exceed the pressure limit on the chiller nameplate or in its service manual; overpressure can damage components such as rupture discs.

What refrigerant phases must be recovered?

Recover liquid first when possible to speed recovery, then recover the remaining vapor. Removing liquid alone is not complete recovery.

Why protect chiller water during evacuation?

Follow the manufacturer’s directions to circulate or remove water. Excessive cooling during evacuation can freeze water in the tubes and damage the heat exchanger.

Why heat chiller oil before removing it?

When applicable, heat the oil to about 130°F before removal to reduce refrigerant release from the oil.

What evacuation level does EPA’s table specify for low-pressure appliances?

EPA’s table specifies 25 mm Hg absolute for low-pressure appliances when an evacuation level is required. Apply the current rules and equipment instructions for the specific repair.

What can a pressure rise after evacuation indicate?

A pressure rise can indicate remaining liquid refrigerant or refrigerant desorbing from oil.

What pressure applies to a specified non-major-repair exception?

For certain non-major repairs under specified conditions, a low-pressure appliance is brought to 0 psig before opening if it will not be evacuated to the atmosphere after service. Confirm the exact rule first.

What work can qualify as a major repair?

Major repairs include removing certain heat-exchange or compressor components, or opening a sufficiently large flow area for more than 15 minutes.