K-Valve torque mallet

[The Chairman]

I own the torque wrenches, but would probably need to add some bigger sizes to my crows feet collection to accomodate all valves. Then I have to figure in the offset, and I really can't remember how to do that, though I am sure I will find it some where. A torque wrench is based on being directly over thefastener with the moment of inertia being generated at the corners of the fastener. A crows foot adds to that moment, with the resultant extra leverage. It's doable, but I have to either get crows feet that are designed to come back over the valve (they do make some like this) or find the appropriate calculations.

 

[TCDiver1]

NetDoc once bubbled...
I own the torque wrenches, but would probably need to add some bigger sizes to my crows feet collection to accomodate all valves. Then I have to figure in the offset, and I really can't remember how to do that, though I am sure I will find it some where. A torque wrench is based on being directly over thefastener with the moment of inertia being generated at the corners of the fastener. A crows foot adds to that moment, with the resultant extra leverage. It's doable, but I have to either get crows feet that are designed to come back over the valve (they do make some like this) or find the appropriate calculations.

Yeah, for some reason i thought mine was adjustable like a crescent wrench but it's not. The other one i have is a socket type drive and that obviously wouldn't work.

In the words of the late great Gilda Radner "never mind."

Whacks and grunts it remains.

 

[pescador775]

For the umpteenth time; 'netdoc' is correct in following the instructor's guidance to seat the valve with a wrench. Light torque, not the 80 ft lbs required with a tapered thread, but the valve must be bottomed. Dive shop operators prefer to be able to spin off a valve by hand and do a quicky inspection replacing the valve manually. However, this is for their convenience only and does not follow manufactures' requirements whether the tank is alum or steel. Interestingly, the shop people sometimes do the same thing with low pressure regulator hoses. This is also a no-no.

 

[deanmartin]

Reviewing the torque specs for the Luxfer and Catalina cylinders the smallest torque mentioned was 50 ft lb.

Thats 50 lbs of weight hanging on a 1 ft long wrench. Now unless your nick name is "wrench wrist" your not going to get there hand tight.

Catalina says that your can whack it with a hammer. Actually they said:

"Hand tightening of the valve should seat the valve completely on the cylinder (i.e. no gap between the valve and the cylinder). If there is still a gap between the valve and the bottom of the cylinder lightly tap the valve handle with a rawhide or rubber mallet to seat the valve completely. If you decide to seat the valve using a torque wrench, following are recommended torque values by Catalina Cylinders and the CGA: "


Thread Designation Catalina Cylinders CGA C-6.1
Recommended Torque Maximum Torque

.750 - 16 UNF 50 lbf-ft 60 lbf-ft
¾ - 14 NGS (NPSM) 80 lbf-ft 100 lbf-ft

 

[The Chairman]

reccomends 60 Ftlbs for all SCUBA and SCBA cylinders.

AND BTW... my nickname in high school was "Vise Grip"... no one could beat me in the hand shake department. Working on cars since I was 12 had it's advantages. At this point in my life though, I see none as I feel quite worn out.

 

[roakey]

That NetDoc is wrong and I'm right. Well, I guess I should mention that he's right and I'm wrong too...

*****************

From: psicylinders [mailtosicylinders@msn.com]
Sent: Wednesday, November 13, 2002 6:26 PM
To: Oakey, Roger
Subject: Re: Valve tightening question

[stuff in reference to something else deleted]

In a sense both of you are correct. The O-ring makers get very upset when people overtighten them as extra tight does NOT make the O-ring work better. The US Divers Co. stated that 30 ft/lb was adequate to seal the valve. And, they described that 30 ft/lb as being a good "whack" with the palm of your hand. We know by experience that the whack is adequate. More recently, the Luxfer Gas Cylinders Co. has recommended 50 ft/lb. that will require a wrench and just a bit of torque across the face of the valve so as to NOT damage the place where the regulator sits. So, either method provides satifactory results. In all the years that I had the duty to replace straight thread valves, I personally used the hand whack and never had a problem.

Bill High, PSI, Inc.

*************

I've always used the hand whack method. Never had a problem (just did two sets of doubles and five stage bottles in the last week). Makes 'em easier to remove, too.

Roak

 

[roakey]

NetDoc once bubbled...
Luxfer Torque Specs

What part of the word "maximum" are you having problems with? Perhaps this is the root of the problem...

Roak

 

[The Chairman]

*Note that this Luxfer torque value differs from that recommended by the Compressed Gas Association. Although CGA recommends 60 lbf-ft, Luxfer tests have shown conclusively that in certain Luxfer cylinders (chiefly for SCBA applications), the 75 lbf-ft torque value is preferable.

Uh... what about this don't you understand??? They want 75 ft-lbs on their valves! It's not like a tire that puts a mak psi of 44 and the car manufacturer says to inflate the fronts to 35 psi and the rears to 28 psi. Of course if the vehicle manufacturer varies too much from the tire manufacturer we have the debacle of the Ford Exploders.

No, the max torque in almost every application is THE TORQUE you should use. Bill is a nice guy, and I like PSI, but with this I will go with the tank manufacturer. Not that I would ever compel anyone to do the prudent thing, and I am not even being smug about it. But there has to be contact between the valve flange and the cylinder. Even a 0.010" gap is enough to enable an O-Ring to fail. I have the seen the O-Rings and I am a believer in keeping them in a captured state.

BTW, this shows that even well versed individuals can be susceptible to taking shortcutsand Roakey, I am talking about you. Very few have your knowledge of tanks, and I respect that. But I got to say; Do it Right... torque it down. Don't create a failure point by playing fast and loose with the manufacturer's reccomendations.

 

[roakey]

That asterisk at the beginning of the text you quoted is there for a reason.

Roak

 

[TCDiver1]

NetDoc once bubbled...
reccomends 60 Ftlbs for all SCUBA and SCBA cylinders.

AND BTW... my nickname in high school was "Vise Grip"... no one could beat me in the hand shake department. Working on cars since I was 12 had it's advantages. At this point in my life though, I see none as I feel quite worn out.

I'll give you a run Pete. I paid my way through college working as a pipefitter. I'm a few years younger than you but i still crack & pop quite a bit when i get up, so the rode hard factor sounds about the same.

I can hear those metacarpals & phalanges poppin now:tease: