Safe pressure testing

[Brian the brain]

A safe way of pressure testing is hydrotesting...

But I don;t really feel like filling my creations with water and putting the fridgy on 'em to raise the pressure...
The fridge will put out enough, around 900 psi, but this envolves a lot of air behind the water, wich stores enough energy to still send stuff flying..

so

My plan is to make some sort of selfcontained sstem, using essentially a small piston, like stirrup pump, to pressurise the water.It could be very tiny, so less force is needed to provide the pressure.Travel would also be minimal..

I'll need hose, for easy connection, a valve to bleed off the air and fittings that can take a heck of a lot of pressure to construct it.
I want to test stuff up to 900 psi.I know small diameter galvanised will take it, so no need for expensive hydraulics..

The force needed to apply the pressure could come from weights, or better yet, my big old vice..

Any thoughts on how to go about??

[twizi]

i thought about this what about a presure washer then u can text to 3000 psi would this work

[Brian the brain]

It might.But I don't have one..

[twizi]

oh i thought u did because of the presure washer handle u can get eletric ones for 4o here in good old america

[Brian the brain]

I would have never taken you for an American..

I ordered the handle, not the washer...


I'm not exactly in the middle of the freaking desert here...I can buy one for cheap but I want to keep it ...simple....
A weight will do...

[jeepkahn]

Gippeto can tell you how to build one, he's linked to them before, they are quite easy to construct and are extremely accurate...

http://www.spudfiles.com/forums/the-fai ... rt,30.html

[twizi]

I would have never taken you for an American..

really i would think i would give the vibe

yeah i would talk with gippeto

[Gippeto]

Ahhh... shucks...

I've suggested the use of a grease gun as a pressure source for hydro testing before. It's still a good (inexpensive, and readily available) idea.

As you've already figured out, stored energy is the thing you need to avoid the most.

First and foremost...get rid of the air in the system.

Hoses store energy, keep them as short as possible or eliminate them entirely. Incorporate a pressure gauge (duh!) and an appropriately rated valve if you want to do the test over time (several hours)

If you look (or ask) around, you probably won't even have to buy a grease gun. Most people I know have at least two. But then, this IS a farming community.

Your situation may differ, but I'm certain you'll know where to find one locally.

[D_Hall]

I know I'm not the first to suggest it but to add emphasis...

In the hobby rocketry world, grease guns are usually used for hydrostatic testing of small pressure vessels. For bonus points, use maple syrup or honey in 'em. Cleanup is still simple (water soluable) but it's thicker than water which means it goes through the gun with fewer problems (some grease guns have issues with a fluid as thin as water).

For larger vessels... Yeah, pressure washers seem to be the standard.

[psycix]

If you can find a grease gun then use that, otherwise, I think the stirrup pump setup will do. I think you can even avoid the hose.
Simply connect a small pipe straight (or with an elbow) to said pressure vessel, and fill everything up with water. Push a piston down in the small pipe and you've got your pressure.

Note that if you displace too less water and plastic deformation would occur, (meaning that your pipe actually is on its way to fail), you can't see it as the pipe doesn't fail yet... (Though, pressure doesn't rise much while the piston travels!)

[Brian the brain]

Greasegun...hmmm..we sell those at my dayjob...

That simplifies things...

I mean I knew how to get to where I want, I just wanted to see if there was a better way, or if I had missed something..

Greasegun...thats genius...

Thanks!!!