to render unit safe

02:21 Jun 14, 2018 

I repeat: the quoted extract from the ST refers to the risk of fire and/or explosion, in the precise context of "cutting or brazing" into the system.

I do not deny that (some, maybe most) refrigerants pose a health hazard - but then so too does "oxygen free nitrogen" (OFN). Except that (odourless) OFN kills (much) faster than (most) (smelly) refrigerants cause "frostbite and eye damage".

Note also, please, that I wrote " The 'risk' referred to in the text is not (directly) to do with anyone's health ..." There are several "indirect" risks: eye damage, frostbite - and death by fire or explosion. In contrast, OFN "directly" suffocates (both fires and human beings).

02:09 Jun 14, 2018 

From this reference:
https://www.safetyservicescompany.com/industry-category/cons...

02:08 Jun 14, 2018 

"Refrigerants used in refrigeration and air conditioning systems must be used properly to avoid potential hazards. Most refrigerants have low boiling points and present dangers of frostbite and eye damage. Refrigerant liquids with higher boiling points can cause respiratory and skin irritation. Refrigerants can also damage the environment if handled improperly"

01:52 Jun 14, 2018 

Have you realised that the ST uses "purge" and "flush" to refer to exactly the same operation - i.e. the removal of potentially dangerous refrigerant vapour by the use of OFN? The 'risk' referred to in the text is not (directly) to do with anyone's health - it relates to the risk of triggering a fire or an explosion if there is flammable vapour in the system when "cutting or brazing" (either of which produces heat and/or sparks).