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


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300psi is not a measure of volume, It's a measure of force (in this case pounds-per-square-inch against the walls of the container). There's therefore no right answer to your question. A person could contain air at a pressure of 300psi in a container of any size, provided the container was strong enough.
cody316 (author)  DELETED_GuardianFox8 years ago
But isnt PVC pipe all the same strength or should i go for something stronger? Would ABS pipe be stronger?
if you pump aps over 120 psi it will shatter in your face
I doubt that pvc can get anywhere near 300 psi, use copper.
 Pvc pipe strength varies with diameter and schedule. For example, Sch 40 1/2" pipe is 600 psi, while sch 40 3/4" pvc pipe is 300 psi.
Ah...just read what you intend to use this for...

pipe burst strength is essentially based on the pipe material, the wall thickness, and the pipe diameter (and this ignores the accumulator end pieces and their adhesion to the pipe...)

So, the answer is absolutely NO.

As for PVC vs ABS... IMO, at the point where a person with no engr background starts to worry about the comparison, it's time to start thinking about building it out of steel, which has significantly greater bursting pressures for the same characteristic diameter/wall thicknesses.
 As far as i know, 1/2" Schedule 40 pvc pipe has a burst pressure of 600 psi, buuut if i were you, i would definitely go with steel pipe.
NO!!!!! PVC pipe comes in different thicknesses, diameters, grades, colors, composition, etc. Some of it comes rated for a modest pressure, some of it isn't. In North America, some comes from Canada, some comes from Mexico, some comes from China, some comes from blah blah... The answer to that is NO NO NO NO NO, not all PVC pipe is the same.

ABS could be stronger or the same strength, I dont know... but the same problems I mention above apply.

Honestly working at 300 psi I reccomend a steel container that has been designed by an engineer with a tested capability of more than 3 times that (for safety).

These pipes are meant to hold water and effluence. They're not meant to hold pressure (although they're often rated for pressure). https://www.instructables.com/id/EV1736XCDFEP286Q1P/ for more details on warnings.

That said, if you truly wish to pursue this... follow closely the instructions of a similar project and purchase piping that has a pressure rating 2-3 times higher than your intended use.
 300psi isn't a volume unit. It is a measure of pressure. You could have any volume and have it at 300psi. But you need a steel pipe reservoir. The longer the barrel, the more time it has to accelerate, thus making it go further and faster. But make sure it isnt PVC, use steel for an extra $40.
Just dont. Never go that high
seandogue7 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
110100101108 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
cody316 (author)  110100101108 years ago
yah thats why im asking the question in the first place, the last thing i want is an exploding PVC pipe
sometimes stuff fails allthough it is not overloaded stuff has to be designed to not make damage or injury if it fails
frollard8 years ago
It needs to be 3 feet long. 100psi per foot. Why, because I said so.
cody316 (author)  frollard8 years ago
you seem to know wat ur talking about, thanks man!
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
Rofl... Oh I have visions of this.
So, we could totally make an infinity pressure holder if we use the whole universe. or not. (thinks - big bang)
I for one am prepared to suffer the consequences of such an experiment. This is science we do here!
lemonie8 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
cody316 (author)  lemonie8 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
lemonie cody3168 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
rich_moe8 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.