Recovery of Refrigerant
Refrigerant Recovery has become necessary due to scientific discoveries that certain chlorofluorocarbons(CFC) are damaging to the ozone layer of earth’s atmosphere. Chlorofluorocarbons contain chlorine, fluorine, and carbon. Because of the negative impact on the environment, recent laws have been passed that strictly control the use of refrigerants in the HVAC/R field.
The process of recovering a refrigerant has to do with the procedures and actions necessary to safely remove and store refrigerants from HVAC/R systems. Current laws have made it illegal to release these refrigerants into the atmosphere.
There are three different recovery methods used in the HVAC/R industry. They are the vapor recovery process, the push-pull recovery process, and the liquid recovery method.
Refrigerant is removed from systems in a vaporous state. The vapor is then condensed by the refrigerant recovery machine and sent to a recovery cylinder.
The steps to do this are outlined here:
- Turn the HVAC system off and ensure the recovery machine is off also.
- Connect a hose from the low-side service port of the air conditioning system.
- Connect the other end of this hose to the center (charging) port of your manifold set.
- Connect a hose to the low-side of your manifold set.
- Connect the other end of this hose to the suction side of the recovery equipment.
- Connect a hose from the tank vapor port to the high gauge on the manifold set.
- Close the valves on the manifold set.
- Open the vapor and liquid valves on the recovery cylinder.
- Start the recovery system.
- Allow the unit to pull into the appropriate vacuum based on refrigerant type.
- Close all valves and disconnect from the air conditioning system or begin purge cycle.
The push-pull method is useful with systems that contain more than 10 pounds of refrigerant and do not have a heat pump, a reversing valve, an accumulator between the service ports, or if the system does not allow the formation of a solid column of liquid. This method is useful for the recovery of large volumes of refrigerant.
To effectively recover refrigerant using this method, the process will also call for one extra hose, a sight glass, and a recovery cylinder with 5 pounds or less refrigerant.
The push-pull steps are as follows:
- Connect a hose from the tank vapor port to the center port of the manifold set.
- Connect a hose from the low side of the manifold set to the suction side of the refrigerant recovery unit.
- Connect a low-loss hose from the discharge side of the recovery unit to the low-side service port. Connect the low-loss hose from the high-side service port to the tank liquid valve.
- Place the tank on a scale.
- Open valves on recovery cylinder.
- Start refrigerant recovery machine.
- Open the low-side valve on the manifold set.
- Monitor the scale.
- Switch the unit over to vapor recovery once the scale stops picking up weight.
This process of refrigerant recovery is similar to the vapor recovery process with the added exception of the use of the high side of the system. This system is also used for the recovery of large amounts of refrigerant.
The steps to the liquid recovery process are as follows:
- Make sure the system you are servicing is turned off and the recovery machine is off.
- Connect the manifold to the system by connecting the high-side to the liquid port, and the low-side to the vapor port.
- Connect a ¼-in. utility hose from your manifold to the suction port of the recovery machine.
- Connect a hose from the liquid side of the recovery cylinder to the discharge port.
- Make sure the ends of the hoses with the shut-offs are used at the suction and discharge ports.
- Purge all hoses of non-condensables.
- Open the liquid valve on the recovery tank and turn the recovery unit on.
- Turn the selector valve on the recovery unit to “liquid.”
- Open the high-side valve and the utility port on the manifold. The recovery unit will work until the low pressure switch turns it off and there is an indicator showing the completed recovery.
- Turn the system off. Turn the selector valve to off.