Support
By Grant Laidlaw
GRANT LAIDLAW
Grant Laidlaw is currently the owner of the Air Conditioning and Refrigeration Academy ( ACRA ) in Edenvale . He holds a Bachelor of Business Administration and an associate degree in educational administration . He has a National Technical Diploma and completed an apprenticeship with Transnet . He has dual-trades status : refrigeration and electrical . He has been involved with SAIRAC for 17 years and has been a Johannesburg committee member for the past eight ( chairman in 2011 and 2012 ). Currently he is the treasurer ( Johannesburg council ) as well as president ( national council ).
WORKING WITH R32 REFRIGERANT
Safe working practices of this refrigerant start with the legal requirement of being registered to do so , and further include tools and considerations .
Johann asks : Grant , there is talk on hydro carbon refrigerants , the flammability aspect and required training , but what of R32 ? Surely some training is required as at the end of the day ? R32 does fall into the A2L category . Can you give some indication as to safe working practice for R32 ?
Johann , we had a look at R32 in the previous issue , and found that R32 is mildly flammable and precautions do need to be taken . By law , all persons working with refrigerants in South Africa need training and need to be registered to use R32 – and / or any other refrigerant for that matter .
To install a system that utilises R32 refrigerant , dedicated tools and piping that have been manufactured specifically for R32 ( R410A ) should be used . The pressure of R32 refrigerant is approximately 1.6 times higher than R22 . Failure to use dedicated piping or incorrect installation procedures can cause ruptures with consequent injuries .
Use a vacuum pump and refrigerant recovery equipment suitable for use with flammable refrigerants .
Electronic leak detectors can be used to detect flammable refrigerants , calibrated in a refrigerant-free area .
Gauge manifold sets specific to R32 should be used . You should not use your conventional ( R22 ) manifold gauges as the system pressures are too high for these gauges . In addition , we do not want to contaminate the refrigerants and oils in the systems .
In order to avoid this , the diameter of each port has been changed to prevent the use of R22 gauge sets on R32 systems . The hose sizes and materials are therefore specific to R32 . The R32 gauges typically can read up to 5.3MPa for a high pressure gauge and 3.8MPa for a low pressure gauge .
Understanding the need to minimise the risk when a flammable gas or vapour is present while the work is being performed is crucial . You should always conduct a risk assessment prior to undertaking any work on a system .
SOME OF THE PRACTICAL CONSIDERATIONS INCLUDE :
• Ensuring that technicians are aware of a potentially flammable atmospheres .
• Checking for refrigerant leaks with an appropriate refrigerant detector .
• Ensuring that there are no ignition sources , for example : open flames or arcing on electrical motors ( brushes ). These ignition sources should be kept sufficiently far away from the site of installation and repairing during which flammable refrigerant can be released to the surrounding space .
• Ensure that the area is in the open or that it is adequately ventilated before working on the refrigeration circuit . The ventilation should safely disperse any released refrigerant externally into the atmosphere .
• Where electrical components are being changed , they must be to the correct specification for use with flammable refrigerants .
• When capacitors are discharged : this must be done in a safe manner to avoid the possibility of arcing .
• There must be no exposed electrical components and wiring whilst charging , recovering or purging the system and there must be adequate earthing .
• If it is necessary to have an electrical supply to the system during servicing , continuous leak detection is recommended .
• If a leak is suspected , all naked flames should be removed / extinguished .
• If a refrigerant leak is found which requires brazing , all of the refrigerant must be recovered from the system , or when possible isolated ( by means of shut off valves ) in a part of the system remote from the leak .
• Nitrogen should be purged through the system both before and during the brazing process .
www . hvacronline . co . za RACA Journal I May 2021 39