Air Cylinders

[Lee]

Does anyone know the rule on how an air cylinder has to be mounted that is going to be used for a pneumatic shifter? For instance, which direction is the regulator suppose to face?

Thanks, Lee

[Brian S]

Not to sound rude, but the rules PDF isn't THAT long, and its searchable. (Edit -> Find in Acrobat)


3.7.4 Compressed Gas Cylinders and Lines
Any system on the vehicle that uses a compressed gas as an actuating medium must
comply with the following requirements:
(a) Working Gas-The working gas must be nonflammable, e.g. air, nitrogen,
carbon dioxide.
(b) Cylinder Certification- The gas cylinder/tank must be of proprietary
manufacture, designed and built for the pressure being used, certified by an
accredited testing laboratory in the country of its origin, and labeled or stamped
appropriately.
(c) Pressure Regulation-The pressure regulator must be mounted directly onto the
gas cylinder/tank.
(d) Cylinder Location- The gas cylinder/tank and the pressure regulator must be
located within the structural portion of the Frame, e.g. they cannot be mounted in a
non-structural side pod.
(e) Cylinder Mounting- The gas cylinder/tank must be securely mounted to the
Frame, engine or transmission.
(f) Cylinder Axis- The axis of the gas cylinder/tank must not point at the driver.
(g) Insulation- The gas cylinder/tank must be insulated from any heat sources, e.g.
the exhaust system.
(h) Lines and Fittings- The gas lines and fittings must be appropriate for the
maximum possible operating pressure of the system.
(i) Protection- The gas cylinder/tank and lines must be protected from damage
resulting from the failure of rotating equipment.

[Lee]

I tried searching it without any luck, and I must have overlooked it in the pdf. Thanks anyways...

[Mike Sadie]

while the rules say that the regulator must be mounted directly to the bottle (ASA), we have gotten away with having a hose in between in the past. It was a stainless braid covered line specifically made for CO2. If this will help your mounting situation, just make sure to clear it with the rules committee before showing up to comp.

[Lee]

We shouldn't have that problem but thanks for the information just incase we do.

[Dave Cook]

While on the subject of cyclinders I thought I would put a comment in about composite tanks. They are incredibly safe and 12 years olds everywhere run around with them on their backs. What is little known is that they have a very low temerature limit when you leave the paintball fields and start working with racecars. They are still safe for race cars from a crash and fire standpoint because they will see a rapid rise in temperature and that will cause a pressure rise that blows the burst disk and vents the tank before the composites start to fail. What I was surprised to learn at first was that the tanks should be kept at a temperature of 150F or less because the resins in the composite become plastic at 180F.

My thought is that these should not be in the engine compartment or aft of the engine or any coolers where they will be exposed to high temperatures. There are aluminum alloy tanks that weigh a little bit more but are rated at a lower pressure. The main difference on the composit tanks is the 4500psi capacity which most people won't have available at the track anyway.

Here are some different tanks and some rough consumption notes

68ci 4500psi composite 45oz
50ci 3000psi Aluminum 50oz
3.5 ounce CO2 (approx 400 shifts) 11.5oz
9 ounce CO2 15oz


50 in^3 storage at 3000psi = 1940 shifts at 1.75 stroke, .75"� dia, and 100psi

You could also run a 20ounce CO2 tank with compressed air at pressures below its 1800 psi limit, I don't know its internal volume and don't have on on hand.

I'd hate to see a ruined event by someone taking shrapnel from a composite tank.

Dave Cook
Paradigm Motorsports