R134a consider as lethal?

[wcw1985]

Dear forum member,

I would like to ask is R134a consider as lethal substance? I read UW-2 stating that lethal substance is gas or liquids that in nature that very small amount of gas or vapor that inhaled by human can be dangerous to life. How to measure the "small amount" in the sentence? Is there a chemical list provided by asme stating that type of liquid or gas that are officially declared as lethal? Thanks in advance.

 

[fegenbush]

If you search on this forum, you will find that this topic has been covered several times.

A brief recap:
- No, ASME does not publish a list of substances that would be considered lethal.
- OSHA (applies to USA only) doesn't have a clear directive on the matter.
- Ask the customer if lethal service is required, they are responsible for that determination.
- If all else fails, use good engineering judgement.

My thinking is that R134a would not be considered lethal. The substance itself is not lethal, but it does have oxygen displacement potential, especially in large quantities. Canisters of it are sold at most auto parts stores in the US. The same cannot be said of anhydrous ammonia or hydrogen sulfide.

 

[wcw1985]

Thanks for your info fegenbush.

 

[moltenmetal]

Even anhydrous ammonia and hydrogen sulphide, chlorine etc. are not universally treated as category M (lethal) service by every owner. Syngases containing carbon monoxide, which is an insidious poison at a comparatively low concentration and which gives no warning signal, are very rarely treated by owners as lethal service. This is an owner's call, depending on the nature of the service, their experience with these materials, proximity to people during operation, pressure, stored volume, propensity for corrosion, availability of ventilation or other leak detection/mitigation means etc. A decision about the fluid service for design codes is only one part of a comprehensive safety in design analysis.

 

[MJCronin]

AAaaagghhh !

http://www.eng-tips.com/viewthread.cfm?qid=308653

 

[moltenmetal]

Poor MJCronin...we pushed his buttons again!

 

[gr2vessels]

Shell has a fairly clear definition of lethal (refer below), being a customer to designers and fabricators. Also, there is a good definition with Australian standard AS 4343, page 18, under notes to Table 1.
LD 50 (oral) mg/kg body mass = LD 50 <=1
LD 50 (percutaneous) mg/kg body mass = LD 50 <=5
LC 50 (inhalation) ppm = lc 50 <=10
Note: LD 50/LC 50 is dose/concentration lethal to 50% of the animals tested.
Cheers,
gr2vessels

 

[MJCronin]

Notice that ASME refuses to come to some commonsense definition of lethal service, whereas corporations such as Shell and juristictional bodies actually address the issue ...!!!

We can't do this here in the United States !

Can we all agree that phosgene gas is to be stored in vessels designed for lethal service.... ??

Can we also agree that air stored at 15 psig, at ambient temperatures is NOT lethal service ???

I suspect that the reason for this has to do with lawsuits suffered by ASME in years past.

I understand that, decades later, it still hurts when ASME sits down......