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how long of PVC pipe do i need to hold 300 psi? Answered

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seandogue
seandogue

11 years ago

Rich makes good points, as do others here... My 2c: Burst strength for schedule 40 PVC tubing is published at ~400 PSI @ room temperature (~70F or 23C), but only for relatively narrow diameter pipe, and it drops to below 300PSI at an ID of 2". Note that wall thickness from mfg variance can be up to +/-10% of expected, so, because the PSI rating is based largely upon the wall thickness (and of course, pipe diameter), things could go very wrong or very right depending on your luck. Good engineers do not rely on luck. Leave that attitude to management (see Challenger and Columbia disasters, both a direct result of luck-driven, "team playin" management types that were (and still are unfortunately) entrenched into the NASA community...Woot! FTW duds!) To err on the side of caution (as most good engineers do when faced with safety concerns), I'd be inclined to use schedule 80, but even then, the numbers fail to meet criteria at 3" diameter. The above applies only to rigid pipe, not flex pipe.. As to the comments on volume, note that volume determines the hydraulic or pneumatic capacitance of the cylinder. That is, having 300PSI is all well and good, but if the voulme is insufficient to do the job, then it fails....length and or diameter are used to provide the capacity to move the target or compensate for system pressure drain during operation (when used as a filtering device or "accumulator", rather than a hydraulic or pneumatic source). Never mind your health, you really want to see your girlfriend, best bud, son, daughter, or other innocent bystander get shredded by your good work?... I wonder if some sort of mesh guard might be a good secondary saftey mechanism...like heavy gauge screen wrapped around the cylinder with some air gap...??? best of luck with your project! Be safe Be healthy

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11010010110
11010010110

12 years ago

the pressure is not related to the length of pipe like everyone else allready said beware of using hard pvc for high pressure air or gases. if it explodes due to a crack you have flying sharpnell that can injure. use a plastic that does not fail violently

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cody316
cody316

Answer 12 years ago

yah thats why im asking the question in the first place, the last thing i want is an exploding PVC pipe

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11010010110
11010010110

Answer 12 years ago

sometimes stuff fails allthough it is not overloaded stuff has to be designed to not make damage or injury if it fails

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frollard
frollard

12 years ago

It needs to be 3 feet long. 100psi per foot. Why, because I said so.

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cody316
cody316

Answer 12 years ago

you seem to know wat ur talking about, thanks man!

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frollard
frollard

Answer 12 years ago

FOR THE LOVE OF GOD I WAS LYING AS A JOKE!

Pipe can hold pressure up to what it is rated. PVC (usually the white stuff) is about as strong as ABS (the black stuff) but abs 'rips' where pvc 'explodes' into shrapnel.

You want roughly 1:1 storage to barrel size. If the barrel (x4 for a net gun) is pi*r2* length
Make the 'storage' the same size

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lemonie
lemonie

12 years ago

The question that you really want answered has something to do with what you want it for - what are you using the pressure for? L

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cody316
cody316

Answer 12 years ago

im using the pressure to fire a rocket, but i dont want shrapnel to fly around and kill me, i'd also like to build the net gun and power it with air

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lemonie
lemonie

Answer 12 years ago

The storage you need is related to the barrel of your gun, and what you're firing out of it. Can you give a rough barrel length, diameter and projectile mass? This'll help us calculate how much air you need and what you need to store it in. L

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rich_moe
rich_moe

12 years ago

Volume of a cylinder has nothing to do with burst pressure. Any length of pipe will hold a design pressure, but the volume will change. Schedule 40 PVC is usually good to about 300Psi, and normally it is printed on the side of the pipe. YMMV if you are putting it in an area that is too cold, hot, or subject to UVA/UVB rays, and/or vibration.