New Tank Valve Help!!!

[Bill Walton]

Ok, I bought a new tank today. Aluminum 100 to dive here locally where a couple of the sites do not have nitrox. (got a faber lp 108 on the way but thats another story)

Anyway, how tight do you screw the valve into the tank? LDS said screw it in and give it a bump but that seems a little loose.

 

[WreckWriter]

Originally posted by Bill Walton
Ok, I bought a new tank today. Aluminum 100 to dive here locally where a couple of the sites do not have nitrox. (got a faber lp 108 on the way but thats another story)

Anyway, how tight do you screw the valve into the tank? LDS said screw it in and give it a bump but that seems a little loose.

LDS is right. Some folks use a rubber mallet, I use the heel of my hand. Be sure the valve is closed (less chance of bending the stem) and give it a whack with the heel of your palm, not too hard but solid. The o-ring seals, not tightness. When there's pressure in it, it ain't going nowhere.

Valves are brass. If you put a big wrench on it you'll twist it right off.

Tom

 

[SDAnderson]

What's the worst that can happen?

Unless you have a torque wrench and have consulted the tank manufacturer (specs vary from one manufacturer to the next), you can't do this properly. On the other side of the coin, most people (and shops) don't have the time or interest to do it properly and seem to survive by tightening valves hard hand tight, plus a little bit.

How lucky do you feel?

 

[WreckWriter]

Originally posted by reefraff
What's the worst that can happen?

Unless you have a torque wrench and have consulted the tank manufacturer (specs vary from one manufacturer to the next), you can't do this properly. On the other side of the coin, most people (and shops) don't have the time or interest to do it properly and seem to survive by tightening valves hard hand tight, plus a little bit.

How lucky do you feel?

I worked the industry for over 10 years, took a VIP inspector class and numerous manufacturer's repair seminars. EVERYONE does it this way because it's the correct way.

You're going to have this poor guy trying to find torque specs and a wrench to do it with, probably cost him a hundred bucks for no reason.

Bill, call a couple shops if you feel the need. You'll find that your original shop was right. This guy is jerking your chain.

Tom

 

[SDAnderson]

Tom:

I wasn’t trying to yank Bill’s chain. Done improperly, the simple act of screwing in a tank valve can create a wide range of havoc, both short- and long-term, as you presumably know. I wanted to convey two things to Bill:

1. The procedure that he had explained to him is the standard and, even though it’s less than perfect, it’s adequate.
2. That he should carefully evaluate the risks he is taking.

Here’s what we know about Bill and his situation:

1. He’s trying to learn, but he doesn’t know what he’s doing.
2. He “just bought a new tank” that needs a valve installed, but his LDS didn’t (or wouldn’t) install it for him.
3. He knows what the standard procedure is for tightening the valve, but he isn’t comfortable with that procedure.

My guess is that he just purchased a tank from an on-line dealer that was shipped by air and, thusly, arrived with the valve removed from the tank. He doesn’t have any experience at this kind of thing, let alone VIP or cylinder filling training, and is about to put together a new tank without any of the equipment, materials or experience that you and I might have at our disposal. It seems likely that he doesn’t know how to take a look inside the cylinder to verify that it’s clean and properly formed, that he doesn’t know how to inspect the “O” ring to make certain it wasn’t damaged in shipping, that he doesn’t know how to lube the “O” ring and valve threads properly, etc. The only piece of information that we know that he has is how to tighten the valve, and he doesn’t believe that.

This may all be yadda-yadda to you, but both he and the guy filling his tanks probably hope that he does it correctly. I support buying gear online and really like the idea of divers learning how to maintain and service their own gear - and I actively do both. I can’t match your experience working in a dive shop, but I have been diving for more than 30 years and I did get PSI training to better manage (and to save a few dollars on) my own bottle collection. Granted, sometimes experience is the best teacher, although the lessons can be painful. Sometimes the experienced are not…

The $15.00 or so he’d spend having a visual inspection done on his tank would seem to be cheap, considering it will get the tank checked out, the valve installed properly, an EOI sticker and probably a free fill.

Gotta go, the water is calling. Peace to all.

Steven

 

[WreckWriter]

Actually Steven when you explain it like that I can't disagree. Bill should take it to a shop and have it done.

Tom

 

[DNAXdiver]

If his concern is that it won't be tight enough, and come off, someone should probably mention that tank valves are in effect "self-tightening" - once pressure is in it, it is not going to come undone. So the point of tightening is just to make sure there's no gap for the O-ring to extrude out of, and if you tighten it "hand tight plus a whump" it'll be fine.

 

[The Chairman]

is captured, so there will only be a modicum of distortion when the valve is tight. The depth is so perfect that the O-Ring seats best when the valve is in metal to metal contact with the tank. The PREFERRED method is to use a large crescent wrench and snug the valve down until you hear the "ring" of a metal to metal contact. This is actually far tighter than you should bang on the valve stem, so don't do that.

The "bang on the valve stem" method has been around a long time, but that does not make it right. It puts a lot of stress on the O-Rings and can bend that thin threaded rod. Best to use a tool to loosen and tighten. BTW, I used to use that system until I took a PSI course... and have not done so since!

As for having the shop do this with an inspection, I concur. You need it vised anyway, and if you don't have the silicone/krystolube for the threads you would be better off taking it to a shop that does.

 

[WreckWriter]

Originally posted by NetDoc
The "bang on the valve stem" method has been around a long time, but that does not make it right. It puts a lot of stress on the O-Rings and can bend that thin threaded rod. Best to use a tool to loosen and tighten. BTW, I used to use that system until I took a PSI course... and have not done so since!

As for having the shop do this with an inspection, I concur. You need it vised anyway, and if you don't have the silicone/krystolube for the threads you would be better off taking it to a shop that does.

So you're claiming that to put a valve on you need a vise and a crescent wrench? You're kidding, right?

I still feel that the original poster SHOULD let a shop do his since he hasn't done it before but I GUARANTEE you they will not put it in a vise nor use a crescent wrench.

Tell me Pete, what do you do on those valves without wrench flats? Do you put the wrench across the valve face?

Tom

 

[The Chairman]

Well first off... I am not kidding. I bought an oversized crescent wrench after my PSI class. Being a former automotive technician, I do have the crow feet to fit them as well, but do feel that is overkill. As of yet I have found few valves without the "flats", but on those without, yes I carefully use the solid brass yoke part. It is far stronger/beefier than the valve stem. I have yet to ruin one, and hope to keep that record for a long time. I have noticed more than a few bent valve stems, which I used to thought they got that way from the tank falling. After seeing one destroyed using the "whack the handle" method, I know what happened.

I know the whack a handle method has been around a long, long time, and that many will continue to do it. That’s “OK”; I don't feel everyone has to do things -my- way. I do offer to those that want to listen an alternative which does the job with less risk to the valve. At least in my mind it is less risk, but all others should make that assessment for themselves. Why don't you contact the valve manufacturers and see how they think the valve should be tightened.

As for cinching the tank down, I have never found that a necessity. I hold it between my knees and give the wrench a good whack with a rubber mallet. Installation is the reverse, but with a slight smear of lube on the threads to minimize galvanic action on an aluminum tank. When I hear the "ring" when hitting the wrench, I know that I have a metal to metal contact between valve and tank, and I stop tightening. BTW, I avoid using the palm of my hand in “whacking” so that I don’t damage the nerves in the carpel tunnel area.