Safety bulletin outlining the precautions to be taken to avoid asphyxiation 



                                    Safety Alert



Ref No 






 Work Place notice boards together with discussion at safety meetings.


An engineer whilst cleaning out the crankcase of a valved-off R22 compressor was overcome by the effects of the refrigerant. The suction stop valve being used to isolate the compressor from the system was damaged and refrigerant was passing from the system into the crankcase. The engineer being aware of this fact incorrectly used his ammonia mask as respiratory protection against the effects of the R22. The engineer became very light-headed and had to be led to fresh air by a colleague. He recovered quickly and dismissed the incident as unimportant, only reporting the facts, in passing, to his manager some weeks later.


R22 has three main effects on the human body:


  1. As an asphyxiant (by excluding air)                                                                                                             R22 is heavier than air. Leaking refrigerant accumulates close to the ground in any poorly ventilated areas such as basements, confined spaces (crankcases, chest freezers) or plant rooms that do not have ground level ventilation.  In the case of larger leaks air will be displaced in the vicinity of the leak.
  2. As a mild narcotic (by breathing high concentrations)                                                                                                                Causes headaches, loss of concentration and tiredness.
  3. As a cardiac sensitiser (by breathing high concentrations)                                                                                                       If a casualty has been breathing high concentrations of refrigerant and is subsequently administered a cardiac stimulant such as adrenalin by a medic, an irregular heartbeat may ensue which can prove suddenly fatal.


The effect of suddenly breathing an atmosphere that contains less than approximately 18% oxygen (air normally contains 21% oxygen) causes the following behaviour in the body. The person will be quite unaware that their behaviour is abnormal. There will be defects in judgement and reasoning with a feeling of confidence, hilarity, belligerence, reduction in vision, weakness of arms and legs leading imperceptibly to unconsciousness. If the oxygen level continues to fall to below 13% or was initially below 13% death can follow rapidly.    


Clearly from the above it can be seen that the early stages of aspyxiation or oxygen depletion have a disorientating effect, possibly similar to a narcotic effect. Therefore, it is impossible to say whether a lack of oxygen or the narcotic effects of the refrigerant overcame the engineer.


REMEMBER in your own interest when working in or entering a space where you suspect a leak:

•    Be careful

•    Increase levels of ventilation (open doors and windows, turn on ventilation).
•    Cure leaks.  
•    Remember that full-face filter masks do not provide a supply of oxygen in an oxygen deficient atmosphere.
•    Ask a second person to observe you from a safe place. Instruct them in what action to take if you appear to be in distress.
•    Remember that other gases displace air (Other refrigerants, Nitrogen, argon used for welding, etc.).
•    If you suspect that an area may be depleted of oxygen do not enter. Call for assistance from your manager, as a full assessment of the situation will be required, as may considerable resources such as oxygen detectors and BA crews.


Last modified: Thursday, 4 July 2013, 9:42 AM