Where can I buy DIY P valve parts?

[Jorbar1551]

I've been looking to build the airspeed press DIY p valve, but for the life of me, I cannot find the parts. The part i have really been looking for, is the elbow. I cannot find a 90 degree elbow with the hose barb on one side, and a male/female couple on the other side.

I've gone to home depot, osh, and mcmaster, but I cannot find the parts. I wouldnt doubt they are there, but could anyone provide me parts numbers?

 

[Camerone]

McMaster - 5372K312 should get you the barb on one side, to a 90 degree male fitting for 1/4" NPT on the other. Tap your DIY P-valve for 1/4" NPT and you should be good to go. They also have a swivel version which may improve hose routing (the 90 degree part rotates...)

[edit - link may not work, but the part number should be right for 1/4" plastic/norprene ID, and 1/4" npt thread]

 

[Jorbar1551]

I didnt know i had to tap the male fitting. I think osh had that part, but i still have to find the reducer from 1/4 to 3/8

 

[Camerone]

You tap a female fitting, not a male fitting. Male fittings are threaded with a die, but this one's already done as part of manufacturing.

Effectively, there's nothing which glues delrin, which is what the body of a valve is usually made of. So, you have to screw in the fitting, which means you have to tap the piece on the suit. If it's the valve I'm thinking of, you have to tap it on the other end, too, to screw the pee-through bolt in, anyway.

FWIW, they have various sizes at McMaster - just search for "barbed fitting" and you should have no problem finding what you want.

 

[Jorbar1551]

I've got all the parts...now I just just have to figure out a way to put the washers on because there isnt much of a seat for them.

 

[Camerone]

Ah - the Airspeed design is a little different than I was expecting. Yah, you just need to tap out the inside of the nylon fitting for the bolt, and not for the nipple-valve body. The 90 degree elbow _is_ the valve body in that design. That's an easy job. I'd be a little wary of the structural strength of that 90 degree elbow. They're somewhat fragile, so be a little cautious.

 

[Jorbar1551]

The 90 degree elbow is made of bronze not nylon. Only the hose couplings are made of nylon

 

[Jorbar1551]

So if im seeing correctly, to close the valve, you tighten the bolt, but you would need to open the valve to expell?

 

[Camerone]

Yup - you gotta loosen it a couple of turns to void. You just have to get it so there's no pressure on the o-ring and the cross-drilled hole is exposed. It helps to slightly chamfer the end of the fitting where you thread in the bolt. Makes it easier to start the bolt, too...

For this, the bolt needs to be cross drilled; once down the axis that you screw in, and once crossways through the bolt, intersecting with the first hole (so that things drain). Very easy to do on a lathe, slightly harder, but still possible on a drill press with a decent vise. Nylon bolts are easier to work with, but you're better off using a brass bolt. Nylon is hydrophilic, which means that over time it will swell with exposure to water, making it both hard to turn and also restricting the diameter that you drilled/bored it out to. Neither is a good thing.

 

[jwin]

While looking through the Mc Masters-Carr Catalog, I came across this 90 degree elbow and pieced together the rest of the parts to make IMHO a more durable P-valve.

5021T36 90 degree hex key 3/8 X 3/8

44555K134 male 3/8 to barb adapter

4568K151 3/8 nipple sch 40

50785K143 thin lock-nut 3/8 pipe thread

All the parts are brass, the 90 is low profile and the end could be trimmed down 1/4" to 3/8" plus it has a large surface area for the washers...

I'm open to opinions before ordering these parts, with a nylon 3/8 X 3/8 tee total cost is around $20.00.

John