Looking For A Light-Weight Cynlinder

Someone else may be able to better answer this than me as this is not my area, but for one it depends on how much pressure you want to hold and how big you want.

A plastic soda bottle can hold up to about 100psi before it ruptures. If you need more than that, you can reinforce it with a carbon fibre layer. I would avoid PVC unless you are way under the pressure rating, as it tends to shatter when it ruptures.

In general if you are looking for something small light and plastic that can hold a lot of pressure, I would reinforce a plastic vessel with carbon fibre.

Hello Frank, Thanks for your help. Reinforce a plastic vessel with carbon fibre.

I'll try that. San Diego Guy

Anything will hold at least 14.7 psi.

Please re-read your question and try answering yourself. It makes little sense as it is written.

do want to chemically bond, screw, weld (heat). does it matter.

All piping has to be rated and appropriate tables can be found by supplier manufacturer.

As to boring a chunk of Nylon, HDPE, UHMW PE, or whatever it is a different matter.

A local Hoby Store that stocks air pistols will have the answer.

A small cylinder shaped in form and function like a tamk of air for that pistol.

The concept might have been taken care of Ya Think???

The concept might have been taken care of Ya Think???

I like this good one. Thanks for your help. San Diego Guy

Yeh I figured that almost anyone with a lathe could turn one out for you, but you said you wanted light. I have seen a few inventive things with those little tanks. So almost anything you make will be heavier and probably trickier to use.

I Dun Know, sounds like fun what are you going to do with the thing?

JRResearch: Why with a name like that, do you ask us for the answers?

"Is there a small cylinder, made of plastic, PVC, etc. or something else that is light wt. that can hold air pressure if so and how many psi 3"X8" cylinder?"

Yes there any number of materials to do that. How many psi depends on both the material and the size and shape.

Are you really interested in only the pressure or do you require a certain volume of air at a certain pressure? Vague questions usually result in vague and moslty useless answers.

Sorry I'll change my name,

Yes there any number of materials to do that. Just one, the lightest and strongest.

put a balloon inside a toilet roll, the roll will keep it shaped like a cylinder, the balloon will keep the pressure, now from there, how much pressure are you after?

The lightest and strongest pressure vessels are (in general) carbon fiber (typically in an epoxy matrix) wrapped, usually using an automated or semi-automated tape or tow winding machine. The fiber orientation and placement can be optimized for the stresses, and the material is inherently very high strength for its weight. If you are careful and meticulous, you can build such a tank in your home shop, using an ordinary lathe as your winding machine. The trick is to keep the carbon to epoxy ratio high, but if you start with pre-preg, you can come fairly close to the weight/strength ratio of a commercial establishment. But you'd need to do a lot of studying beforehand: an exploding tank -- especially a carbon fiber one, can do a great deal of damage.

It would not be difficult to machine a cylinder of PVC or HDPE or any other reasonable plastic for that matter. The questions are: How much pressure, how much heat, how much weight, what wall thickness, chemically resistant or not, and how many do you want? Do you want a quote? Send me a drawing. I cannot predict what wall thickness would be required to withstand your pressure requirement, but I could most likely prototype your parts for you.

So it isn't pipework with a type-approval pressure rating?

Then the following methodology might be suitable:

There is a relationship between the ultimate tensile stress of the material at the maximum operating temperature, its thickness, and its ability to withstand stress. Take slices through a theoretical cylinder and do the calculations. Get a second competent person to check the calculation and file the results as a formal record.

Once a suitable thickness for the selected diameter has been found, multiply by a suitable safety factor - say 3 times? Check that the cylinder material is at least this thickness.

Once the cylinder is built and assembled, do a hydraulic test to, say, 1.5 times the operating pressure to prove it will withstand 1.0 times the operating pressure.

Fit a pressure relief valve to this vessel to lift at the maximum operating pressure.

Once happy, repeat the tests in front of the Inspector-Surveyor responsible for the organisation's insurance cover. Obtain written documentation that the vessel is fit for purpose and that the organisation's insurance policies cover the use of the vessel. This test will need to be repeated at intervals to satisfy the insurance company's inspection and test interval criteria.

That's it.

Tri-Star Plastics (800)323-3311 provides a CJ Bearing, which is polymer/PTFE lined, then wound with glass roving and epoxy. This is very light and can be pressurized. The inside diameter can be changed to a variety of polymer reinforcements and machined to custom diameters, within reason.

Tri-Star Plastics, Thanks for your # we will be calling your company and maybe we can go more into detail on what I would like to do. Who should I ask for?

Thanks again San Diego Guy