Sharing the failures as well :) HH machine

I like your use of the manufactured dry box as a fabric holder.

Does it use pressurized air or water to test the fabric?

Does your test give the max pressure held with no leakage? Or are you able to measure some leakage/time at a particular pressure?

Springboarding off your use of the dry box, I'd try a very small dry box (less fabric area means less force on the sealing rim). Something like one of these:

One end could be drilled and tapped for 1/8" pipe thread for a pressure gauge to measure leakage. The other end could be drilled for a schrader valve to pressure it off of a bicycle pump.

And if you left the middle of the top and bottom free of connections, the dry box could be reinforced with a C-clamp.

I'd be wearing a face shield whenever anything was pressurized.

Cause stuff happens.

Edited to add: I notice you also keep bamboo flooring around. I like it's strength, density, and uniform fine grain. The flooring I got is about 1/2" thick, but it glues together nicely for thicker, stronger pieces.

Am going to make it simple as possible

Pressurises with water

The dry box is not good the plastic is just not strong enough, so will be using the end pipe cap in last picture.

In the hose there is an locking lever,

So you can pressure up, flip the lever and hold the pressure as long as you want.
Also the is a safety valve in the pressurizer container, so its easy to release the pressure gradually.

I will wait for the usual 3 drops to appear and measure at that point, to can adjust the pressure very fine increments with the pump.

Good tip on the safety glasses will dig them out :)

Also: the flooring are samples per cut from B&Q about £3 :) really handy

Have you considered PVC pipe fittings? They can safely handle well over 100psi and some of the screw caps might work well to clamp the fabric, sort of like a canning jar lid.

I'd second the use of a bicycle pump w/ pressure gauge and install 2 tire valves on the pressure chamber: one to attach the pump, the other for pressure bleed w/o disconnecting the pump. You're pumping air, but you just have to put some water in the chamber.

The PVC just didn't work for me, too big and bulky.
Wanted it so can pack it away so flexible push fit tubes work well :)

I will go with the setup I have no point in changing it,
Its only the box to fix now, I think the large end cap will work.

I only need to go to 15 psi as that's about 10000mmHH and enough for what I need.

One other thought:

Gather the edges of the fabric sample around the hose end and secure with a hose clamp. When pressurized the fabric would inflate like a ball. No need for any sort of box at all.

You'll probably have to re-enforce the hose end against collapse by inserting a short piece of metal pipe or barb fitting, and you might want to place some tape or bicycle tube rubber between the hose clamp and fabric to keep the clamp from cutting the fabric.

It might end up leaking where the fabric is gathered and folded over on itself. But this is about as simple as it gets so may be worth a try before building another pressure chamber.

nice setup using available materials

pump spray tank is good idea

For those who may not know, there was a spate of HH testing in early 2011. Lance Marshall lead the DIY way with This Setup.

Once Richard N. acquired a HH test machine and graciously offer to test samples, the “need” for ones own device declined.

Is anyone else besides the OP doing their own testing, or hoping to do so?

Yes, I have my own test rig. I built it myself over several evolutions. I think Richard bought his.

Compressed air goes through a double needle valve bleed system to create a controlled slowly rising pressure. This pressurises water on the underside of the sample with a rising 'head', which is measured by the pressure gauge and by a static water column which is not shown here. I can freeze the system when the required 3 drops of water appear on the top surface. That is the 'HH' according to the Standard, but we usually want to know a bit more about the fabric behaviour.

The seal is between the fabric and a layer of rubber on the underside. Note that if this seal leaks slightly, it simply does not matter. Pressure is pressure. The seal is driven (forced, loaded, whatever) by either PVC tube or clear perspex tube, on top. That's controlled by the screw thread at the top.

Here we have some silnylon fabric leaking under pressure. The drops of water ALL appear along the ripstop thread lines, because it is those thicker threads which destroy the effectiveness of the silicone coating. Use plain weave rather than ripstop and the HH goes way up, but the gear mfrs are mostly ignorant of this and like the techie term 'ripstop' for marketing reasons.

I have tested a lot of fabrics like this, way past their nominal HH value which is when just 3 drops appear. The leak rate is sort-of linked to the over-pressure. In some cases you get micro-sprays of water appearing.

Someone wrote a PhD thesis recently which claimed to be the first to ever test beyond the nominal HH. Obviously, their literature search did not include BPL! Oh well, no matter.

Cheers

That is a totally awesome rig and setup :)

I am making gear for other people
And I want to make sure 100% what the fabric is capable of before it is used by friends.
I really don't trust the suppliers or their numbers I want to have my own reference.

Also there is a lot of fabric out their that has no information, you never know might find a gem :)

Gary,

If you think you found a gem, compare your "when new" number after wet flexing through field use or artificial aging. Many fabric gems rapidly loose their luster with use.

Plan to do that,

Lots of flexing, storing in a stuff sack compressed etc,
I will produce a spec sheet for each fabric I use with all the details on and that will go with the products.

Flexing when wet is a good idea.

:)

Here’s a link to the thesis Roger speaks of.

thesis

I know a few of these fabric mentioned have been tested.
It would be great to see the lighter fabrics go head to head.

Nobul2
Argon .67
Momentum 50
Phantom
Ventum

Then move to the lightest "claimed" 10,000 hh fabrics.
Pertex's
Nano Pro Membrain

And so on…