In article , says...

"djay" wrote in message
news:MsDFe.7064$vY2.2412@trnddc09...
You should only use ONE of the washers, not both!
They will be either a felt or nylon. If you use both washers you will not
have the correct seal.

Djay

But according to the website, http://www.jbjlighting.com/pdfs/CO2_Manual.pdf
it says to use both washers?


That is unfortunate. The manual is also advising one to use teflon tape on the
threads, which play no role at all in providing a gas-tight seal. This shows a
lack of understanding on the part of the author, and their suggestion to use two
washers should be rejected.

The fitting on CO2 cylinders is a standard design listed as CGA-320.
(CGA=Compressed Gas Association) A single nylon washer and light to moderate
torque on the nut will provide an excellent seal. Also, the cylinder valve should
be opened all the way against the stop (compressing the internal seal) so one does
not depend on the stem packing to provide a gas seal. If the components are
undamaged and you use the single washer, the chances of having a leak on the high
pressure side are nil.

You can test with some children's bubble liquid, the commercial product, or your
own mixture ( usually soap or detergent with glycerine, diluted in water ).

George