Why is my tank valve leaking?

[mark99]

I just purchased a PST E7-120 and have noticed something unusual compared to my experience with the Al-80 tanks. Many times when I attach my reg first stage, and turn on the tank, I notice a leaking around the valve-regulator interface. Sometimes it makes a loud hiss and then kind of a pop and it is sealed. Occasionally it just has a tiny leak and I have to shut it off and re-seat the regulator. I replaced the O-ring with the spare provided by PST (they are Viton O-rings) and the first time it seemed to do the trick, but now after 3 or 4 times placing the regulator it is happening again. It doesn't leak every time, maybe about 50% of the times. With the same regulator, I have never once had a similar problem when using an AL-80. As you may know, this is the PST with 200 bar (5 thread) DIN valve with factory installed yoke adaptor, and I am using a Scubapro MK25 first stage with yoke fitting (rated to 230 bar). Anybody else had this experience?

 

[dlndavid]

I have a PST E7-100 using MK25 and no leaks. How is the Reg seat-seal area condition? Any nicks?

 

[Corigan]

Have you tried changing the o-ring on the inside of the din insert? You can remove the din/yoke insert with a hex/allen wrench and you will notice there is o-rings on both sides of the insert. If you bought the tanks locally, you could just take em back and have the shop look at em for you.

Matt

 

[crpntr133]

Have you tried changing the o-ring on the inside of the din insert? You can remove the din/yoke insert with a hex/allen wrench and you will notice there is o-rings on both sides of the insert. If you bought the tanks locally, you could just take em back and have the shop look at em for you.

Matt

Or the insert may not be tight. One time you may get the yoke just a bit tighter than the next or you may twisting it a bit and tighen/loosen the insert.

 

[mark99]

I have a PST E7-100 using MK25 and no leaks. How is the Reg seat-seal area condition? Any nicks?

Appeared to be in new condition, I will check again carefully.

Have you tried changing the o-ring on the inside of the din insert? You can remove the din/yoke insert with a hex/allen wrench and you will notice there is o-rings on both sides of the insert. If you bought the tanks locally, you could just take em back and have the shop look at em for you.

Matt

I did not know there was another O-ring on the other side of the yoke insert. Is it the same size as the "outer" O-ring? So I assume the yoke insert is tightened up against the "inner" O-ring, does this mean the insert needs to be tightened a certain amount, or to a certain depth, within the DIN channel? Is it possible overtightening renders the adaptor too deep, creating too much space between the adaptor and the regulator?

 

[Sandworm 40]

This problem surfaced recently with some PST E7-100 at my LDS. The O-ring which makes the seal between the valve insert and the yoke fitting of your regulator first stage is probably incorrect from the factory. A larger O-ring will fix the problem. This problem was not consistent with every manufacturer's regulator, just some. Your LDS will probably have an O-ring which will work, but I suggest you also contact PST via your purchasing source to inform them of the problem.

 

[mark99]

This problem surfaced recently with some PST E7-100 at my LDS. The O-ring which makes the seal between the valve insert and the yoke fitting of your regulator first stage is probably incorrect from the factory. A larger O-ring will fix the problem. This problem was not consistent with every manufacturer's regulator, just some. Your LDS will probably have an O-ring which will work, but I suggest you also contact PST via your purchasing source to inform them of the problem.

First I had to be a steel tank/valve 200 bar/230 bar/300 bar/ 7 thread/5 thread/ DIN/yoke adaptor expert to understand my PST tank, now I'm afraid I'll need to be an O-ring expert to get it to work. So looking up the possible O-ring sizes, I see that the Viton 014 is the standard O-ring for the "standard tank/regulator", with nominal 1/2" inner diameter and 1/16 " width. Any ideas what would constitute a "larger" O-ring? It appears that the next size up is 3/32" width (I assume you don't mean larger to be a bigger diameter)?

I do appreciate that I'm not the only one who's had this problem. Thanks.

 

[Sandworm 40]

You're correct, by larger O-ring I mean the O-ring's thickness needs to be thicker, and not bigger around in diameter. I couldn't tell you which O-ring to get by part number or size, this incident occured at my LDS in my presence but I'm not privy to the actual description of the O-ring which solved the problem. The problem stems from the failure of the O-ring to seal due to the contact of the valve face and the yoke. That contact keeps the yoke just far enough away from the O-ring to allow a proper seal. I suggest you take the tank and your regulator to your LDS and let them find an O-ring which will work. If this isn't feasible, contact PST. My LDS informed them of the problem when they found it. so PST is aware. Like I said, it's just a problem with some yokes, not all. Good luck.

 

[Leadking]

There are a limited number of Thermo valves shipped with an insert that was ISO designed, and as it turns out, the design was flawed. It is not a safety issue but a inconvenience issue. The inserts were shipped with purple o-rings (not to be confused with the new ones with purple o-rings and 1/4" hex key opening) Contact your dealer and have them request a new insert being provided at no cost by Thermo Valve.

REMEMBER THE GOOD INSERTS HAVE PURPLE O-RINGS AND 1/4" HEX OPENING

 

[mark99]

There are a limited number of Thermo valves shipped with an insert that was ISO designed, and as it turns out, the design was flawed. It is not a safety issue but a inconvenience issue. The inserts were shipped with purple o-rings (not to be confused with the new ones with purple o-rings and 1/4" hex key opening) Contact your dealer and have them request a new insert being provided at no cost by Thermo Valve.

REMEMBER THE GOOD INSERTS HAVE PURPLE O-RINGS AND 1/4" HEX OPENING

Well that's very interesting, I chased down the specs for the Thermo valve and it does appear that the correct O-ring for both sides of the adaptor (insert) are V112, these are the Viton 1/2" inner diameter and the 3/32" width. So I suppose if they were shipped with the "standard" yoke O-rings V014 (2/32" width) then they would be prone to leak. Maybe that was a design flaw, making the insert too narrow and requiring non-standard O-rings??