EDITOR’S NOTE: Recovery of refrigerant may be a common practice in HVACR servicing, but it is still a skill that requires care and caution. The following instructions were provided by Refco. While specific to the company’s Enviro recovery unit, awareness of step by step procedures can help all technicians better understand what’s involved in the process. As always, service technicians are encouraged to contact the manufacturer of the unit they have for detailed recovery instructions – and to follow them precisely.
The ENVIRO is a recovery machine for a broad range of refrigerants. Recovering refrigerants into a separate storage cylinder involves a process of gas compression, resulting in high pressure within the machine, the connecting hoses and the storage cylinder. High-pressure systems must always be treated with care and respect to prevent careless accidents.
Only a qualified technician who has been properly trained in the use of such equipment and in the recovery process must operate the ENVIRO. Skilled personnel are workers who, through their specialized training and operational knowledge of the recovery machine, are capable of carrying out the described work and independently identifying potential hazards.
Operation
1. Do not mix different refrigerants together in one tank, or they cannot be separated or used.
2. The knob should be at ‘position 0’ before operation. All the valves must be closed, the input and output fittings should be covered with protective caps when the unit is not in operation. The air moisture is harmful to the recovery result and will shorten the life span of the unit.
3. A filter drier should always be used and should be replaced frequently. And each type of refrigerant must have its own filter. For the sake of ensuring the normal operation of the unit, please use the filter specified by our company. High quality filter driers will bring quality services.
4. Special caution is needed when recovering from a burned out system, and two filter driers are needed.
5. The unit has an internal high pressure shut-off switch. If the pressure inside the system is above 558 psi, the compressor will automatically shut off the power. To restart the compressor, please lower the internal pressure and hit the high pressure button, and then turn on. When high pressure protection is initiated, please find out the cause and deal with it before restarting the unit. Cause of high pressure protection and troubleshooting: a.) The input valve of the refrigerant tank is closed – open the valve to solve the problem; b.) The connecting hose between the recovery unit and refrigerant tank is stuck – close all the valves and replace the connecting hose; c.) The temperature of the refrigerant tank is too high, pressure is too high – give it some time to cool down and the pressure will come back to normal.
6. An electronic scale needs to be used together with the recovery unit to monitor the recovery process.
7. In order to gain maximum recovery speed, a hose with inner diameter bigger than .16 inches is recommended and the hose should be shorter than five feet.
8. While recovering large amounts of liquid, use the push/pull mode.
9. After recovery, make sure there is no refrigerant left in the unit. Read the purge operation carefully. Liquid refrigerant remaining in the unit may expand and damage the components.
10. If the unit is to be stored or not used for any length of time, we recommend that it be completely evacuated of any residual refrigerant and purged with dry nitrogen.
11. Connection hose with check valve is recommended. It can prevent refrigerant loss.
12. The intake port is equipped with filter screen; please wash it frequently to keep it clean.
13. If it is difficult to start the unit, please turn the knob two rounds to balance the internal pressure and make it easier to start.
14. The low pressure gauge shows the pressure of the intake port of the compressor and the high pressure gauge shows the pressure of the outlet port.
15. After using, please turn the knob to ‘0’ position.
Recovery Method
1. Turn the knob to position ‘1.’
2. Correctly and firmly connect the hoses.
3. Connect the unit to the right power supply (as shown on the name plate), turn the power on to start the unit.
4. Open the valve of the refrigerant tank. (Figure 1.)
5. Open the liquid valve on the manifold gauge.
6. Slowly turn the knob to position ‘2’ for faster recovery. Notice: a.) If liquid impacting occurs in the compressor when at position ‘2,’ please turn the knob to position ‘start’ slowly. The reading of the low pressure gauge will decrease until the impacting stops. But the pressure should be above ‘0’ because the intake port cannot intake when the pressure is ‘0’. If it is difficult to start or restart after power off, please turn the knob to position ‘START’, then turn on the power and hit the RESET button; b.) If the knob is turned to position ‘1’ and the unit is running, a stable recovery of liquid will occur in the compressor when at position ‘1’. Slowly turn the knob clockwise to the position ‘start.’ The reading of low pressure gauge will decrease until the impacting stops. The pressure should be above ‘0’ because it cannot intake if the pressure is ‘0’.
7. When liquid recovery is finished, turn the switch to position ‘2’ for faster recovery.
8. After the low pressure gauge shows zero, start the purge operation. (Figure 2.)
Self-Purge Method
1. No need to turn off the power; turn the knob to position ‘3’ to start purging.
2. Purging ends when the required vacuum is reached. a.) Close the valve on the refrigerant tank; b.) Close the check valve on the connecting hoses; c.) Close the liquid valve and gas valve on the manifold gauge; d.) Close the connecting valve between the refrigeration system and the manifold valve; e.) Turn the power off, and disconnect all the external hoses; f.) Cap the intake port and the outlet port. (Warning: After each use the unit must be purged to make sure there is no refrigerant left in the unit. Remaining liquid may expand and damage the components.)
Liquid Push/Pull Mode
1. Turn the knob to position ‘1.’
2. Correctly and firmly connect the hoses.
3. Turn the power on to start the unit. When recovering more than 22 lbs. of liquid refrigerant, push/pull is recommended. (Warning: An electronic scale needs to be used together with the recovery unit to monitor the recovery process. Once the siphon is started, it can overfill the recovery tank. The siphon can continue even if the machine is turned off. You must manually close the valves of the tank and unit to prevent overfilling.) (Figure 3.)
4. Open the gas valve and liquid valve of the refrigerant tank.
5. Turn the knob to position ‘2’ to start push/pull recovery mode.
6. When the electronic scale is not changing or changing very slowly, it means the liquid recovery is finished and it’s time for gas recovery. (The hoses need to be reconnected and please follow the Purge Operation to purge the gas refrigerant.)
7. Close the gas valve on the refrigerant tank and then turn the power off.
8. Close all the valves and disconnect all the external hoses. Connect the hoses according to the Recovery Operation to do the gas refrigerant recovery.
9. Purge.
To review the entire document upon which this article was based, go to http://www.refco.ch/upload/enviro_manual.pdf. Next month, we will focus on proper maintenance of a recovery unit.
