"Francis Rowe" wrote in message
ink.net...
Not trying to get into a fight here, but PVC was suggested to me 8 years
ago by a friend who was a professional mechanic.
Is there a reason a pipe that's rated to handle 400 pounds liquid can't be
trusted with 100 pounds of gas?


YES
Gas is easily compressed and will expand with great force when there is a
rupture. Liquid under pressure barely compresses and if it lets go, there
will be very little movement of the container and shrapnel.

Where I worked many years ago, we used to test heating coils with air in a
tank. They would fill them with 50 psi in a tank of water. When high
pressure units were built, they were hydrostatic tested up to 3000 psi
because of the safety factor of pumping liquid under pressure. The were
bench tested as it was not considered dangerous

Your friend may be a professional mechanic, but that does not mean he knows
about plastics, air pressure and the resulting hazards. OSHA does not allow
PVC, nor do the makers of the tubing allow it. A Google search will find a
lot of information on the subject.

I understand there is a new material that is acceptable for air use but do
not recall the specifications. Rubber hose rated for air can also be used.
--
Ed
http://pages.cthome.net/edhome/