Si Tech Inflator Leaking

[decidedlyodd]

So my SiTech drysuit inflator valve has been leaking air lately. It started out only happening occasionally, but seems to now happen on every dive. It is not a high volume leak but rather more gradual. When it's been particularly bad I can descend without hitting the inflator at all and still feel almost no squeeze. However, usually I just notice that I'm venting a lot even when staying at a constant depth.

Today I took the inflator off my suit and hooked it up to a regulator on a tank. The hissing was immediately obvious, but at least it confirms there's an equipment problem instead of me just making excuses for struggling with my buoyancy. First, I soaked it in a vinegar and water solution for about 15 minutes.

No change, so then I proceeded to disassemble the thing...



It was pretty straightforward but I did have to peel the Bare sticker off the button to get at the second allen screw.

I cleaned everything again (water/vinegar, scrubbed with brush, etc.) and relubed the O-rings with some Trident silicone grease I have. Still no luck. It still hisses when hooked up.

The metal post shows some corrosion and the O-rings have some fairly good sized imperfections on them.



Is this just a matter of replacing the O-rings? If so, does anybody know what size these are and where I can buy them?

Or is this thing toast? I've seen them for $78 from DRIS* or for about $35 shipped from Seaskin in the UK. Seems like quite the racket but I'd like to have my suit back in order ASAP.

* There's some text on the SiTech US distributor's site about DRIS not being an authorized dealer and some text on DRIS's site saying they refuse to buy from the US distributor.

 

[Couv]

If the o-rings have visible signs of damage start there. Measure the inside diameter and cross section and find a chart to get the correct o-ring size. Here is a typical chart: O-ring Sizing Chart Having said that, if the o-ring is stretched it is better to measure the outside diameter of the groove the seal sits in the find the i.d. of the o-ring.

Here is a link you may find helpful:
SiTech Drysuit Inflator Valve Disassembly

 

[TSandM]

I've had really good luck putting the metal parts through the ultrasonic cleaner and replacing the o-rings. Unfortunately, I don't know the size. I have a fairly large supply of o-rings, and I just picked the ones that fit.

 

[decidedlyodd]

From that other thread, it looks like the standard #8 or #9 o-rings will fit. Unfortunately, none of the ones in my (albeit somewhat limited) collection fit. As for where to buy them, everything I can find locally indicates only large B2B sales. It looks like there are a few places online that will sell me some for a few cents plus way more for shipping, but it beats the heck out of $80 for a new inflator, right?

 

[Peter_C]

I have a couple brand new inflators I would be willing to part with. Say $40 shipped? I believe one is a Si-Tech. PM me if you want one.

Otherwise if there are no pits or damage just replace the o-rings to the one you already have.

 

[Couv]

From that other thread, it looks like the standard #8 or #9 o-rings will fit. Unfortunately, none of the ones in my (albeit somewhat limited) collection fit. As for where to buy them, everything I can find locally indicates only large B2B sales. It looks like there are a few places online that will sell me some for a few cents plus way more for shipping, but it beats the heck out of $80 for a new inflator, right?

A local hardware or automotive store should have a variety of sizes. If not, pm me with the dimensions and your snail mail address and I send you some.

 

[decidedlyodd]

I was able to order a kit with a bunch of different sized rings for $12 from Amazon including shipping. Hopefully, it'll do the trick but if not I'll PM Peter about the new inflators. Thanks everybody for the help!

 

[Couv]

Good luck and keep us posted.

 

[decidedlyodd]

The o rings I ordered came in today. The #008 sized ones look like a perfect fit, but after replacing them I'm still getting hissing. It's much less pronounced than before, but unfortunately that still means there's a slow leak. If I fiddle with the inner post by tapping or rotating it, I can get it into a position where all hissing stops. However, it seems pretty touchy and this isn't something I'd be able to do in the field or underwater.

Looking more closely inside the valve body, it appears that there may be some damage to the wall that the o ring seals against. In the picture below, the round hole towards the right is where the air comes in from the inflator hose. Just to the left it appears to be a chunk taken out of the sidewall. I'm guessing this is what's causing the seal to not properly form.



I'm not sure how this came about. Maybe some sand or other hard foreign body got blasted in through the inflator at some point then abraded the o-ring(s) and sidewall. My partner bought the same model suit at the same time I did in the spring of 2011, but he started having this same problem later that summer (about 2 years ago). Bare ended up fixing the problem under warranty, most likely by switching the valve out.

So it looks like it's time for a new valve... I have to say though that it's at least been educational disassembling and fiddling with this thing.

 

[Couv]

While it may be best to replace the valve, give these suggestions a try-you may end up with a usable spare:

Roll up a piece of 400 grit sandpaper and abrade the discrepant area. Make sure you clean out all the grit before putting it back together. Lube the o-rings. BTW If you're using silicone o-rings do not use silicone grease.

Jax mentioned replacing the -008 o-rings with -009, so that might do the trick or perhaps a combination of the two.