For years, refrigerant has been used to purge air from the service hoses prior to making the final connection to the unit. Obviously this causes refrigerant to be released to the atmosphere. To comply with the no-venting requirements, certain precautions must be followed when connecting or disconnecting the gauge manifold set.
When connecting the gauge manifold hoses to a system for the purpose of charging, any air trapped in the hoses must be removed. If this is not done, the air will contaminate the system. The need to purge the hoses can, for all practical purposes, be eliminated if the hoses are equipped with fast-sealing fittings. Such fittings greatly reduce the chance of air entering the hoses. They also prevent the hoses from becoming contaminated when not in use.
Should you need to purge the service hoses, follow steps 1 through 6 below.
1. Connect the low-side and high-side hoses loosely to their matching service ports on the unit (Figure 3-17) – Make sure both gauge manifold set valves are front-seated.
2. Attach the utility hose to the refrigerant cylinder. Crack the valve on the refrigerant cylinder.
3. On the gauge manifold set, crack the low-pressure valve for no more than two seconds, then close it. This allows the refrigerant to displace most of the air from the manifold and hoses while allowing only a minimal amount of refrigerant to escape.
4- Tighten the hose connection at the service valve or low pressure service port.
5. Repeat the procedure for the high-pressure hose.
6. Close the valve on the refrigerant cylinder.