EPA 608 Technician Certification High-Pressure Recovery Requirements and Techniques Summary

Table 1 in 40 CFR 82.156 requires 0 inches of mercury for a high-pressure appliance under 200 pounds, with either older or newer recovery equipment. With 200 pounds or more and newer equipment, the level is 10 inches.

Wrong choices

• 15 inches of mercury vacuum: 15 inches applies to medium-pressure appliances with 200 pounds or more.
• 25 mm Hg absolute: 25 mm Hg absolute applies to low-pressure appliances.
• 10 inches of mercury vacuum: 10 inches applies to high-pressure appliances with 200 pounds or more.

Removing liquid first moves most of the refrigerant much faster than removing it as vapor. After the liquid is out, recover the remaining vapor.

Wrong choices

• Warm the recovery cylinder: Warming the recovery cylinder raises its pressure and slows recovery.
• Recover vapor first and liquid last: Recovering only vapor first is slower when there is a lot of liquid.
• Use longer hoses: Longer hoses add restriction and slow recovery.

For a high-pressure appliance with 200 pounds or more, Table 1 requires 10 inches of mercury vacuum with recovery equipment made on or after November 15, 1993 (4 inches with older equipment).

Wrong choices

• 4 inches of mercury vacuum: 4 inches applies when using equipment made before November 15, 1993.
• 15 inches of mercury vacuum: 15 inches applies to medium-pressure appliances with 200 pounds or more.
• 0 inches of mercury: 0 inches applies when the charge is under 200 pounds.

Under 40 CFR 82.156(a)(1), if a repair is not major and is not followed by evacuation to the air, a medium-, high-, or very high-pressure appliance needs to be evacuated only to 0 psig before opening.

Wrong choices

• 5 psig: 5 psig is allowed only for oil changes.
• 25 mm Hg absolute: 25 mm Hg absolute is for low-pressure appliances.
• 10 inches of mercury vacuum: 10 inches is a Table 1 level for some appliances, but non-major repairs need only 0 psig.

40 CFR 82.152 defines a major repair as one that removes the compressor, condenser, evaporator, or auxiliary heat exchange coil, or uncovers an opening of more than 4 square inches of flow area for more than 15 minutes.

Wrong choices

• Tightening a flare nut: Tightening a fitting does not remove a component.
• Replacing a thermostat: A thermostat is not part of the refrigerant circuit.
• Replacing a fan motor: A fan motor is not one of the listed refrigerant components.

Recovery works because refrigerant moves from higher to lower pressure. Chilling the recovery cylinder lowers its pressure, and heating the appliance (not with a flame) raises its pressure. Both speed up recovery.

Wrong choices

• Cooling the appliance being recovered: Cooling the appliance lowers its pressure and slows recovery.
• Heating the recovery cylinder: Heating the cylinder raises its pressure and slows recovery.
• Using the smallest hoses available: Small hoses restrict flow.

EPA's test topics say to wait a few minutes after reaching the required vacuum. If the pressure rises, liquid refrigerant or refrigerant dissolved in the oil is still boiling off. Continue recovery.

Wrong choices

• Air has been fully removed: This test is about refrigerant left behind, not air.
• The recovery is complete and the system can be opened: A pressure rise shows recovery is not complete.
• The vacuum gauge is broken: A rising pressure is a normal sign of leftover refrigerant, not a broken gauge.

40 CFR 82.156(e) says system-dependent recovery equipment may not be used with appliances with a full charge of more than 15 pounds, unless it is a pump-out unit permanently attached to the appliance.

Wrong choices

• 5 pounds: 5 pounds is the small appliance limit.
• 200 pounds: 200 pounds is a break point in the evacuation table.
• 50 pounds: 50 pounds is the leak repair threshold for ODS appliances.

R-134a is a medium-pressure refrigerant. For a medium-pressure appliance with 200 pounds or more, Table 1 requires 15 inches of mercury vacuum with equipment made on or after November 15, 1993.

Wrong choices

• 10 inches of mercury vacuum: 10 inches applies to medium-pressure under 200 pounds or high-pressure 200 pounds or more.
• 0 inches of mercury: 0 inches applies to high-pressure appliances under 200 pounds and very high-pressure appliances.
• 4 inches of mercury vacuum: 4 inches applies when using older equipment.

Under 40 CFR 82.156(a), technicians may evacuate either the entire appliance or just the part to be serviced, if the refrigerant in that part can be isolated in a system receiver. The technician must verify the required level before opening.

Wrong choices

• Venting the isolated part since it is small: Venting is illegal.
• Recovering the entire system no matter what: The rule allows evacuating only the part when refrigerant can be isolated in a receiver.
• Opening the part without any evacuation: The part to be opened must still be evacuated to the required level.