www. refrigerationandaircon. co. za RACA Journal I June 2025 55
Support
• Refrigerant weighing scale
• Vacuum pump and refrigerant vent-line
• Inline filter drier place inline at inlet of recovery machine
• Blower for the ventilation of working area with capacity of 700 m ³/ h.
• Suitable flammable refrigerant gas detector
• Personal protection equipment( PPE)
• Safety area warning signs
PREPARATION FOR RECOVERY Safety precautions:
• Inform owner and / or supervisor and obtain permit of work if required
• Isolate the refrigeration system
• Place the warning signs within the work area
• Connect a ground strap between recovery unit, recovery cylinder and operator to prevent static electricity, build up
• Wear Personal Protection Equipment as required.
• Check all equipment is in good working order
• Label the recovery cylinder with the correct type and maximum filling weight of the refrigerant to be recovered
• Place the recovery cylinder on a calibrated scale
• Place the end of the vacuum pump vent-line at a safe place within outside ambient
• Switch on the gas detector( leak finding device) in‘ fresh air outside condition’ and place it in the floor area next to the equipment arrangement
• Check that all temporary refrigerant hose connections are tightened
• Maintain air circulation with blower
RECOVERY Then do as follows:
• Operate the recovery unit according to the manufacturer’ s operation instructions
• Observe operational parameters at manifold gauge, recovery unit and gas detectors
• Fill the recovery cylinder carefully and monitor the weight of the cylinder- and therefore the transferred refrigerant- with the scales
• Do not exceed the maximum charging capacity of the cylinder
• When a container is filled with refrigerant, the maximum charge should always be observed by using a calibrated weighting scale, considering that possible refrigerant mixtures have a lower density than pure refrigerant. The usable container capacity should therefore be reduced. It should be noted that the density of R290 at 50 ° C is 0.449 kg / dm ³ and the density of R600a at 50 ° C is 0.517 kg / dm ³. The charging capacity is a result of the internal volume of the container and the liquid density of the refrigerant at a reference temperature( 70 % liquid by volume at 50 ° C). Do not exceed the allowable pressure of the container, even temporarily, during any operation
• Monitor the discharge pressure to ensure that the maximum allowable pressure of the recovery cylinder is never exceeded. When 0 kPa level is observed on the low side manifold gauge, close both side manifold valves and turn off the recovery unit to prevent possible entry of air during recovery process. Do not pull the system into a vacuum with the recovery equipment
• When pressure on low side manifold gauge starts to rise, repeat operation
• Electric heating with the crank-case heater can be used to accelerate this process
• When the low side manifold gauge remains at 0 KPa, close all cylinder, manifold and hose valves
• Note the actual recovered refrigerant amount and update the recovery cylinder label
• Remove the recovery cylinder from the weighting scale, put sealing caps on connection ports
• Connect a suitable vacuum pump and evacuate the system to 1000 Microns in order to remove residues of refrigerant from the system
• Once the complete evacuation is complete flush the system through with nitrogen rendering the refrigerant circuit inert
• Prepare and execute subsequent repair / service work
• Fill system logbook with relevant data
AFTER RECOVERY The recovered refrigerant should be returned to the refrigerant supplier in the correct recovery cylinder. Do not mix refrigerants in cylinders. If compressors or compressor oils are to be removed, ensure that they have been evacuated to an acceptable level to make certain that flammable refrigerant does not remain within the lubricant. The evacuation process shall be carried out prior to removing the compressor from the system. When oil is drained from a system it must be disposed of in the correct manner.
Check the filled recovery cylinder for the existence of noncondensibles by doing a temperature / pressure comparison.
This is done by placing the cylinder in a stable environment for 10 hours or overnight. Measuring temperature of the bottom quarter of the refrigerant cylinder. Place a manifold gauge set on the vapour service valve on the cylinder, open the value and record the pressure. The pressure should correspond with temperature on the pressure temperature chart for the specific refrigerant. Should the pressure reading be higher than what is indicated there are non-condensibles present in the cylinder. Following all the safety rules applicable to venting flammable refrigerants, vent the non-condensibles out of the cylinder until the pressure corresponds with the temperature as indicated on the chart.
MARKING OF RECOVERY CYLINDERS WITH FLAMMABLE REFRIGERANTS
The cylinder containing recovered refrigerant should be marked to note any special conditions, for example:‘ HC R-290 – Recovered’. A red band on the shoulder or top of the container should designate flammable compounds, or mixtures that could become flammable in the event of a leak.
FIRST AID MEASURES Should exposure to a refrigerant occur the following first aid measures should be followed:
www. refrigerationandaircon. co. za RACA Journal I June 2025 55