RACA Journal May 2021 | Page 42

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• When transferring refrigerant into cylinders , ensure that only the appropriate refrigerant recovery cylinders are used .

• All cylinders to be used are designated for recovered refrigerant and labelled for that refrigerant . Cylinders must be equipped with a pressure relief valve . Empty recovery cylinders should be evacuated before use . Calibrated weighing scales should be used to avoid overfilling of recovery cylinders . It is very important not to mix refrigerants in recovery machines and 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 .

When breaking into the refrigerant circuit the following procedure represents good practice :

• Removal of refrigerant from the system .

• Purging the system with nitrogen .

• Evacuate , ensuring that the refrigerant is removed from the oil ensuring that the outlet of the vacuum pump is not close to any ignition sources and that there is ventilation available .

• Perform a second purge of the system with nitrogen .

• It is now safe to work on the system including brazing .

Purging can be achieved by breaking the vacuum in the system with nitrogen and continuing to fill until the working pressure is achieved , then venting to atmosphere , and finally pulling down to a vacuum .

When installation / repair is complete a follow up leak test should be carried out prior to leaving the site .

Given the increased pressures of R32 over R22 it is necessary to use seamless copper pipes suitable for R32 / R410a . Do not use copper pipes which have collapsed , deformed or damaged areas . Never use copper pipes with a wall thickness less than 0.8mm .

Thanks for the question Johann , in terms of refrigerants , we are experiencing rapid , global change and need to ensure our knowledge , procedures and equipment are keeping abreast with changing technology . Flammable refrigerants are , without doubt , here to stay .

Thank you for all your questions . Send your problems ( and sometimes your creative solutions ) to acra @ netactive . co . za with ‘ Solutions Page ’ in the subject line . You may include pictures . RACA

RACA Journal I May 2021 www . hvacronline . co . za