Support
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 over two decades and served on the Johannesburg committee as chairman and was also president between 2015 and 2018 . Currently he is the SAIRAC national treasurer .
WELCOME TO THE
SOLUTIONS PAGE
By Grant Laidlaw
Many people ask for assistance in the understanding of theoretical and practical aspects of the industry . I will endeavour to enlighten . I am going back to basics as I have questions coming in which indicate that the basic understanding necessary to work in industry is not in place .
42
Margaret asks : I am an apprentice , and our company does fridge repair . Could you please explain the service and repair issues when working with hydrocarbon R600a . I have seen people taking out R600a and simply replacing it with R134a where I work , they say it is safer .
Hi Margaret , I would imagine that you work in the smaller capacity domestic refrigeration market where you are running into R600a .
Replacing R600a with R134a is very poor practice . This also means that when removing the R134a for repairs you should recover the R134a from the system , something which I am reasonably sure does not happen .
R600a has been used to replace R134a because R134a is an HFC . HFCs are currently being phased down . Why ? R134a has a high potential with regards to global warming and releasing R134a into the atmosphere is detrimental to the environment . In contrast , R600a has a very low impact on global warming . Fridge manufacturers are producing environmentally safe units running on R600a , but all the good work is being destroyed when a technician replaces R600a with R134a .
South Africa signed the Montreal Protocol which primarily addressed the ozone depletion issue . The subsequent amendments , in particular the Kigali Amendment ( featured elsewhere in this issue ) deals with global warming substances . This means that as a country we are committed to the phasing down of global warming substances such as R134a .
Margaret , it is true that there exists an additional safety issue when working with hydrocarbons ( HCs ). They are flammable , but with basic knowledge and easy to follow processes and precautions this risk can be reduced to low levels . There will always be some risk , but this also applies to R134a and in fact all refrigerants . Therefore ,
RACA Journal I May 2023 you should conduct a risk assessment before you start work to assess the possible risks and to take the necessary action to make the workplace safe . Margaret , let us begin with what is R600a ? R600a is an HC and as such is flammable . R290 is also an HC and should you run into a light commercial fridge or beverage cooler you will , in most newer models , find that the unit utilises R290 . The same safety rules apply . R600a is pure iso-butane and has a boiling point of -12 ° C at atmospheric pressure ; R600a is used in most , if not all new domestic refrigerators in South Africa . All refrigerants must be extremely pure . They must have extremely low levels of moisture and other contaminants . The use of impure HCs will cause the following problems :
• High levels of moisture may saturate the filter drier , freeze in the capillary tube and can lead to compressor damage and failure .
• HC refrigerant manufacturers do not add a stenching agent and thus concentrations of HC refrigerant cannot be smelled .
• HCs when used as a fuel are not the correct composition for a refrigerant . It will not give the correct refrigeration capacity , and its use may result in higher running costs and poor reliability .
Therefore , only use refrigerant grade R600a .
FLAMMABILITY HCs are flammable when mixed with air and ignited . The concentration of HC in the air must be between the lower and upper flammable levels as shown below .
• If the concentration is below the lower flammability level ( LFL ) of approximately 1.8 %, there is not enough HC for combustion . www . refrigerationandaircon . co . za