5 replies to this topic

[MortenHansen]

Dear people of wetpixel!

Wondering if anyone out there has a lot of experience opening tank valves?

I have 100 tanks here in my diving center, I have already opened them all a few times for our 6-monthly cleaning+visual inspection.

My problem is that there are too many valves getting scratched and some even breaking when we open them.

The methods I have tried so far:

1: Custom made steel-rod with DIN-thread on one end

-Insert tank into custom made "tank-clench" (so it does not rotate)
-Put plenty of teflon tape on the thread
-Insert rod into DIN thread of tank valve
-Open with a hard, but gradual, push from the thigh

The problem with this solution is that the valve-tread has a tendency to break
(1/10 valves= 10 valves in total=600$ every 6 months, excluding all the other spare parts)

2: Monkey wrench at valve-base

-Insert tank into custom made "tank-clench" (so it does not rotate)
-Use large monkey wrench+cheater pipe to open valve

The problem with this solution is that the valve base gets some serious pressure marks from the monkey-wrench

Does anyone have any "out of the box ideas" how I can open the valves without risking breaking them?

Does anyone know of any commercial tools for opening scuba tanks?

Best regards, Morten.

[jahjahwarrior]

The 2nd method is the better one. You don't need a monkey wrench, get the right size wrench and guard it with your life.

Get it nice and long, and apply a slow even pressure.

Don't put the valves on with very much pressure. Some say hand tight is right, but I think the proper torque is a bit more than hand tight. Also, use Cristolube or Tribolube on the threads of the valve when putting it back in the tank. You don't need a lot. (I think you could use silicone grease as well, if you aren't using anything but air in the tanks. Personally, I prefer to avoid it anywhere near my breathing gas)

Breaking valves is a sign that you are putting them on too tightly, and probably getting some galvanic corrosion between the threads of the tank and the valve.

Edited by jahjahwarrior, 04 November 2012 - 05:59 PM.

[ChrigelKarrer]

i agree with jahjahwarrior
You close them too tight or you have a serious issue with galvanic corrosion between the tank and the valve.
When opening the tank you should use a round brass brush to clean the tank treads and a special sanding disk tool
to clean the o-ring seat.
Apply a very thin film of cristolube and screw them down hand tight and then "a bit more"
You should use only christolube or other oxygen safe grease on any tank parts as you never know if they get filled - for whatever reason - with Enriched Air or even worst with pure oxygen.
The additional price for oxygen safe grease will be only a few tenths of dollars more.
Chris

[adamhanlon]

There are specific valve "spanners" available.

It sounds to me like the problem you are having is that the valves are too tight. Valves going into alu cylinders should not be torqued over 60 ft lbs. While the "tight and than a bit more" approach will work some of the time, it also results in valves seizing as you have discovered.

Adam

[Alastair]

just an idea from a rig hand.... if, and you should have the right wrench for the valve, buy a strap wrench (some have a bicycle chain and others have a webbing strap) and place it so that when you lie the tank down it opposes the torque that you are applying from the valve wrench, this way when you use your body weight to release the valve thread the other wrench will provide backup although you may need someone to hold it down if it is really seized. And then as the others have said use the right grease compound and torque them up correctly i am sure there is a rule of thumb for torque and weight + length of the spanner which if i drag my mind back was called moments at A level maths??... which i was not very good at... but you should always check that you can back them out and then remake them.

[MortenHansen]

Thanks everyone for the input!

Finally I bought a fixed 38mm wrench and it works a lot better than the large monkey wrench- the compression marks that I saw when using the monkey wrench on the valve base are nearly non-existing when using the fixed wrench.

From now on the tanks will be closed by hand + an additional tap with a rubber mallet- last time they were closed with a large monkey wrench which is for sure why we had so much problems opening them this time around!

-Morten

You don't need a monkey wrench, get the right size wrench and guard it with your life.

hehe, oh yearh, wrench is now locked away inside my tool-cupboard!