Properly Install A Tank Valve - Scuba Tech Tips: S12E03

How does your local dive store fit a scuba tank valve holding 3,000 psi (207 bars) without leaking? Alec shows the tools, tips and force needed (not much!), to properly install a scuba tank valve.
Picture credits:
- tank valve on/off indictor: XS Scuba
- scuba valve cross section + taped thread: www.scubaboard.com, Akimbo
- tank valve cut-off: www.cyltest.com.au
Watch my "Alec Peirce at the Ranch" for ranch and home ideas. / @alecpeirceattheranch
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[@Caderic]

I was just thinking yesterday..."I haven't seen an new Scuba Tech Tip in a while. I really need to get to the ranch channel." Now there's a new video, but I still need to get to the ranch channel. ...And thanks Canada, for sharing your weather with us in Texas! LOL

[@davids7550]

Yee Haw Dude, eh?

[@Caderic]

@@davids7550 HA, HA, HA!

[@AlecPeirceScuba_SeaHunter]

We only loaned you some some, please mail it back! Thanks Erikk and glad to give your something to look forward too. There are weekly At The Ranch videos out Tuesdays and Kevin and I shot a lot before Christmas.

[@tomaszzdziech5457]

Hah, was just assembeling my stage tank couple of weeks ago and wondering if "hand-screwing" of the valve would be enough. I actually had a thought "What would Alec say about it" :-D thanks for ensuring me that I did it properly! :) Best regards from Poland!

[@AlecPeirceScuba_SeaHunter]

Always trust your "WWAD" What Would Alec Do inner voice. Thanks for sharing and hello Poland.

[@PROSTO4Tabal]

Alec Peirce is my hero. I learned a lot of knowledge from his channel. Thanks !

[@TheJoeyboots]

Yes he is a Scuba Guru. LOL

[@AlecPeirceScuba_SeaHunter]

Mine too! Appreciate the feedback my friend.

[@kirkthejerkthe1st]

Alex, not that it matters in this application, but the crow foot wrench would actually alter the true reading of the torque wrench by a little.

[@timgosling6189]

Yes, you'd need an adaptor to keep the axis in line with the valve.

[@AlecPeirceScuba_SeaHunter]

Possibly but hand tight with one light tap has worked for me for 40 + years of tank servicing.

[@j3o5h8n5j5a3y8]

Yes, trigonometry at work. But you can calculate the actual torque. Look up "torque wrench offset calculator". As you said, not a big deal here, but a good catch on your part.

[@Engineer9736]

I was about to comment the same. Though whatever you do i would make sure that the valve cannot undo unintentionally. Tap it with a mallet at least.

[@weberswonders]

Great video again. Love to watch this guy. My son and I have learned a lot from you. Thank you

[@AlecPeirceScuba_SeaHunter]

Great to hear young divers can learn from us stone age divers.

[@TheJoeyboots]

This man has a real intense love for the sport. I can see the twinkle in his eye. ;)

[@AlecPeirceScuba_SeaHunter]

Thank you very much.

[@xinzhouliu]

Definitely one my favorite KZbinrs. Always something to learn from him.

[@maxtorque2277]

Ignoring the old style taper threaded valves, which there are stilla few floating around, the critical fact to remember is that the O ring not only acts to SEAL the valve to tank interface, it also acts to LOCK that interface solid when under pressure! The O ring is soft, and when air pressure in the tank seeps up the threads, it pushes on the back of the O ring. The other side of the O ring is basically atmospheric pressure, so that air pressure pushes the O ring into the corner between the small chamfer machined into the top of the tank threadm and the right angle corner formed when the valle body winds down and touches the neck of the tank. For a typical tank o ring, which is 3.2mm section, and about 26mm ID, a tank at 200 bar is is actually pushing that O ring into that traingular section with a force of about 5,300 Newtons (530 kg, 1172 lbs) and being soft rubber, it obviously deforms and gets 'wedged' into that gap. This has now formed not just the pressure seal, but that force, through the friction of the rubber on metal, provides a massive resistance to the valve turning in anyway. Added to that, the valve itself experiences a huge force due to the air pressure acting on the bottom of it, for a typical valve, that force is about another 11,000 Newtons, and because the threads have friction, that force provides yet another "locking" force, preventing the valve from turning. This means the ONLY reason to in any way torque the valve into the tank, and effectively reload that joint, is to prevent the valve turning when there is NO air pressure in the tank, and we all know we should never leave our tanks with NO pressure in right? The other interestig thing you see is modern valves have a drilling latererally from about 1/4 the way down from the top of the valve thread that goes into the centre tube, ie is exposed to the tank air pressure via an un-impeded path, ie not up and around the threads. That drilling does two jobs 1) it applies pressure to energise the O ring, to actually ensure it does seal immediately 2) Should somehow someone manages to unscrew a valve is attached to a tank that has air pressure still in it (and realistically, for the reasons mentioned, this is broadly impossible about about 50 bar) then before the threads become fully wound out of the tank, that drilling allows a controlled amount of air to vent. This, whilst scaring the crap out of the person doing the unthreading, means the valve shouldn't come shooting out of the tank like a bullet when it is unscrewed sufficiently for the last few threads to fail under the load!! BTW, a typical brass valve assembly has a mass of around 450 to 500grams, so with that 11kN of force on it with a 200 bar tank, if it were to be freely ejected it would accelerate at 22,000 meters per second per second initially, an acceleration of 2,243g, and accelerate to about 42 meters per second (94 mph) before the last thread had left the tank! That you DO NOT want to be stood infront off Physics is fun right? Although not as fun as diving, so get those tanks filled and get under :-)

[@TheJoeyboots]

Woo Luv it!

[@AlecPeirceScuba_SeaHunter]

I taught high school science for several years so we both are true science nerds. Much appreciate your excellent feedback Mr. Torque. Thanks for watching sir.

[@paulbaratta1566]

Happy to see your doing well Alec! Snow is melting and it’s almost dive season in New England! Time to get that regulator serviced and inspected for the new season

[@AlecPeirceScuba_SeaHunter]

Absolutely. Smart divers get it done now when dive shops are not busy, and need your support, to be ready to get wet. Have fun in New England but I'm now at the point where 84F is my minimum! Dive safe my friend.

[@jonnieinbangkok]

Super informative and valuable information on valves and tanks 👍👍👍

[@AlecPeirceScuba_SeaHunter]

Glad you liked it A

[@darrylblondel4154]

Over the years or should I say decades I've always wondered how they removed and refitted my pillar valves without a scratch on them. Very interesting, as always. cheers Alec.

[@AlecPeirceScuba_SeaHunter]

Well Darryl, I have a video coming out shortly on 1/2" pillar valves so keep watching.

[@connorh6523]

If you're using a crowsfoot with your torque wrench, it's essential to adjust your values! For a two foot torque wrench, a one inch crows foot increases the force applied by 5%, meaning you actually need to set your wrench at 38.4 ft-lb to get a torque of 40. It's a bigger issue if you use a shorter torque wrench or longer crows foot.

[@AlecPeirceScuba_SeaHunter]

Thanks for the tip. A

[@nathanjohnson9231]

Another great video Mr Peirce! While not necessarily important for this, as the 40 pound feet of torque is well below the breaking point of the parts, for a torque value that needs a Crow Foot accessory, the torque wrench should be perpendicular to the Crow Foot off-set. As you mentioned, using a standard open end wrench and a scale 12 inches from the center of the part being torqued would have the same affect as a torque wrench. By adding the Crow Foot to the end of the torque wrench, you're effectively adding a few inches, so it's 40 pounds of pressure at 15 inches, which increases the torque on the part 25%. Not going to make a difference for this, but could if someone has to use a similar set up on a more fragile part, or one at a higher torque value. It's great seeing how all this works, and I've watched most of your videos from the last several years. I just wanted to throw that bit of caution in.

[@AlecPeirceScuba_SeaHunter]

For an exact measurement, it must be perpendicular. Showing viewers all the right and OK options to give the valve enough holding torque. Some like 2 light hammer taps, others the crow-foot and torque wrench. Trying to keep everyone happy (a little anyway). Thanks for the feedback Nathan.

[@jacquespoirier9071]

the thread on these valves is 3/4 NPS ( Sational Pipe Straight ) it is an heritage of the old lead pipes, the exterior diameter is 1.050" and on the old lead pipe, the interior diameter was 3/4 " these type of fitting is called ORB (O Ring Boss) and it is widely used in hydraulic applications, On theses fittings, seating is mandatory but the torque spec is optionnal. On such a big thread, torquing from 10 to 100 foot pound does not rotate the valve ( or fitting ) more than 1 or 2 degree so torquing to 40 foot pound have no significative effect. As usual, your video is a nice resume of the installation on a valve after a visual or hydrotest inspection.

[@AlecPeirceScuba_SeaHunter]

Thank you Jacques and for the detailed information on pipe threads for others to read.

[@timgosling6189]

I'm just swapping a couple of valves to paired modular ones for sidemount. I remembered this video from earlier in the year and it was a very useful refresher. Thank you Alec :-)

[@AlecPeirceScuba_SeaHunter]

Glad it helped Tim. Think of this as your reference library with a crazy attitude.

[@vinnycostanzo7019]

Alec thank you for always sharing your Knowledge in such great detail, God Bless You!

[@AlecPeirceScuba_SeaHunter]

I appreciate that Vinny.

[@HhhHhhh-pe8qt]

Thanks Alec

[@AlecPeirceScuba_SeaHunter]

You're welcome.

[@jonathanstaley3883]

Fantastic! Thanks! This answered a lot of questions!

[@AlecPeirceScuba_SeaHunter]

Very welcome!

[@keithrobinson870]

Great video!!

[@AlecPeirceScuba_SeaHunter]

Glad you enjoyed it

[@timgosling6189]

That was really interesting. Although with my 'Zen And The Art of Scuba Maintenance' hat on there seems to be a big difference between hand tight/a few taps with a soft mallet and 40 ftlbs with a torque wrench. I think if it doesn't look all the way home with the first method I'd take it out, check and have another go before trying the second!

[@AlecPeirceScuba_SeaHunter]

The tank makers had to have a mathematical max force limit to satisfy lawyers as 'hand tight plus 2 taps' is not a good legal defence to a service tech using the Hulk method!

[@Iannuzzi14]

Hi Alec thank you thats a great video ! I was wondering if you could show hoe to open MSA cylinders? Thank you so much 😊

[@AlecPeirceScuba_SeaHunter]

MSA are not approved for scuba and I don't want divers to thing they are safe to use.

[@royharrison1301]

Love watching your videos, very informative. But may I suggest in the future you get a good night sleep and drink plenty of coffee beforehand to combat any lethargic tendencies you might display ;-)

[@AlecPeirceScuba_SeaHunter]

Ha, Kevin has to slow me down some times I'm so perky in the mornings. Thats for the advice. A

[@BodyWorkInProgress]

Hi Alex, can you do a video on how often you should change your regulator hose?

[@AlecPeirceScuba_SeaHunter]

I think i covered that in one video on replacing hoses. It's probably in the early part around why should hoses be replaced then how to do it. I'll ask Kevin to check if we covered it and if not, it will be added to my ideas list for future episodes. Thanks mate.

[@thomaslombard8058]

Hi Alec. Not sure if you have already addressed this in one of your other tech tip videos but when screwing/unscrewing the valve from the tank, is it normal for there to be the slightest wobble or is it supposed to sit rock still as they thread in and out?

[@AlecPeirceScuba_SeaHunter]

After the light tap with a rubber mallet to loosen the o-ring grip, it should be snug, like unscrewing a faucet, not lots of play. The o-ring seals the air inside at 3000 psi but the threads hold the valve in place. If you think there is more 'play' than should be, take it to a dive shop and ask them to check the threads or at the next Visual Inspection date mention it. Good questions Thomas.

[@emilianogarcia8191]

Hello, what is the size of the crowfoot wrench you are using for the sherwood valve, which will be the genesis valve size?,.. thank you for answering

[@AlecPeirceScuba_SeaHunter]

Most tank valves are 1 1/2", a few are 1 1/4". For a crowfoot wrench, check out: scuba-clinic-tools.com/products/cylinder-1-1-2-crowfoot?_pos=1&_sid=673524d02&_ss=r

[@bdoody7748]

alec I am about to work on a college engineering project for hydrodynamics.. I am going to do it over the average scuba setup.. what topics can you recommend for technically inclined people how it works example is Bernoulli's and Boyle's equations . going to be bringing my tanks steel and aluminum, regulators, and Bcd for in class examples Thank you for your time

[@AlecPeirceScuba_SeaHunter]

Well you cannot go wrong watching my videos for tips, facts and education. Your welcome to use them in your project in full or cut/paste what you need as long as you get a A+. Look back for my videos on the basic setup, overfilling (don't), hydro testing. Add in scuba myths like: don't leave in the sun #1 AND #2 (I use Kelvin in this one). There is lots of ideas for you to include and show how smart divers are compared to skiers!!!! Good luck and let me know latter how it went.

[@tomagneessens2417]

Hello, where can I find or what is the brand of that valve torque wrench showed @ 10min20s on the video ? Thanks a lot in advance.

[@AlecPeirceScuba_SeaHunter]

The crows foot attachment is available from many sources. Two options: a one piece like I show or just a snap in foot to an extender. Search www.shop.snapon.com for the part.

[@shoot4naveen1]

Hi Alex, how do you remove a tank valve which doesn't have a flat face to hold the adjustable wrench?

[@AlecPeirceScuba_SeaHunter]

Using the largest wrench you have, put it over the valve and burst disk extension, give several taps with a rubber mallet and it should open. Use the reverse to put it back on after service. The o-ring does the sealing so little torque/muscle is needed to seat the valve in place. A

[@AbidKhan-rb5kx]

Sir i found these in Catalina diving cylinder specification.... "VALVE BURST DISC ASSEMBLY" Tighten safety burst disc to 50-55 Inc-lbs apply torque rapidly to avoid gasket deformation.

[@AlecPeirceScuba_SeaHunter]

Sounds right. The disk is very thin and its a one time tighten. Don't get it right, replace and repeat. Keep watching as I have a video where i show a burst disk blowout. Maybe in early March. A

[@jabertagi3857]

Can you do a video on types of tanks and their benfits or cons

[@AlecPeirceScuba_SeaHunter]

Are you a mind reader? I have a video coming on steel vs aluminum tanks and discuss the pros and cons of each. Stay tuned.

[@jabertagi3857]

@@AlecPeirceScuba_SeaHunter oh perfect! Will you be able to include benefits of high pressure tanks and low pressure, will high pressure tanks have more breathing time?

[@davids7550]

Hey guys, about time for Silver Springs isn't it?

[@AlecPeirceScuba_SeaHunter]

It would be except for that tiny pandemic and all the Sea Hunt Forever cast are really, really old (except for me). Not this year and we make a decision in August to go so see how comfortable the cast is with 2022. Thanks for asking.

[@AbidKhan-rb5kx]

Sir plz mention for me that how much torque force required to catalina or luxfer scuba cylinder assembly to open or closed..

[@AlecPeirceScuba_SeaHunter]

I don't have access to the service manual that give an actual number but as i said 'hand tight' with a rubber mallet tap is fine. Remember its the o-ring, NOT the force of metal to metal, that holds the air it. I have done it this way for decades with no problems. A

[@AbidKhan-rb5kx]

@@AlecPeirceScuba_SeaHunter thank you sir for your kind reply.I have some experienced about to hand tight and then by hitting rubber mallet hammer than while charging the diving clynder from air compressor there was a leakage from the neck just because of habd tight.

[@scubaclient355]

Cylinder manufacturers advocate not damaging the cylinder, yet dive outlets smash indents into the crown. Hitting the valve wheel with a mallet can damage the spindle. You may not notice gas leakage until you use Trimix.

[@AlecPeirceScuba_SeaHunter]

The proper way is to 'tap' the valve to seat it but some believe it must be torqued to the max. Look for a future video on taper vs straight tank valves to show divers the big difference.

[@TheJoeyboots]

I brought my AL80 tanks in for a hydro. They are old tanks like 80 and 85. The shop said 1. They need a microfracture check of the neck, 2. They are old tanks and should be replaced. Either way I have them back minus the hydro and fill. They did not have the device for the neck fracture analysis, and kind of hinted that they might not have done the hydro because of the tank age. Your thoughts on this Mr. Peirce?

[@mattdecker7141]

They will make nice bells!

[@TheJoeyboots]

@@mattdecker7141 Ha Ha Ha ohhh nooooo!

[@TheJoeyboots]

@@mattdecker7141 I thought the whole idea of the hydro was to ensure the integrity of the tank. I believe they measure the expansion and contraction and that would indicate if the tank has succumbed to the pressure and is overstressed. If they pass hydro no matter what the age they should be good to go. If that is not the case what is the point of a hydro, it cant be accurate then.

[@davids7550]

@@mattdecker7141 Na, Need steel. Aluminum does not resonate - it's too thick. I even tried baking one to relax the metal - still no go. They would make good air compressor holding tanks or portable tanks to fill a tire though. I made table lamps out of mine.

[@davids7550]

Probably Luxfor tanks USD sold with a lifetime warranty. Lifetime of the tank. Not many places will deal with those things anymore due to the poor aluminum mix. I made nice table lamps out of mine.

[@scubasteveandunderwaterroc3547]

Do you have a video on how the tank valve works?

[@Caderic]

I am interested..."Underwater Rock climbing".

[@scubasteveandunderwaterroc3547]

@@Caderic that's a really hard production to pull off. As of right now we focus on the underwater part.

[@AlecPeirceScuba_SeaHunter]

Not on its operation but maybe in the future I could do one.

[@sorel456]

What is the purpose of the dip tube?

[@AlecPeirceScuba_SeaHunter]

It prevents any contaminate inside a tank such as dust, rust, etc, from directly entering the 1st stage when inverted otherwise you may inhale it.

[@evynpohlman5444]

My dive shop told me that if a tank valve is removed,moisture from the air as well as debris could get in and corrode/rust the inside of the tank, and the debris could clog the valve. What are some of the details/truth to this statement?

[@evynpohlman5444]

I want to do it myself but if there is risk for damaging my tank and valve, is I'll just take it to a dive shop

[@AlecPeirceScuba_SeaHunter]

Ok, but it is not a problem when they remove the valve fully to do the annual visual inspection or 5 year hydro test? Once an inspection is done tanks are filled with filtered, dry air ready for diving. They may have meant when out diving a tank should definitely never be taken down to empty as the outside air pressure would match the tank pressure possibly allowing moist unfiltered air into the tank (note very small amounts). Which may accelerate internal corrosion before the next annual visual or hydro test. Hope this clarifies the empty tank situation.

[@davids7550]

Sometimes it can be much easier to unscrew a valve by opening the valve first. Especially if you hear air escaping thru the now open valve. OK-OK - situational comedy. I take 'em as I get 'em.

[@AlecPeirceScuba_SeaHunter]

Not all of us are Hulk strong. I still shake my head at some divers/stores that still believe more torque is a better seal. That is until the threads snap on a customers tank.

[@lupusdeum3894]

Wanna borrow one of my rubber mallets? 🦈

[@AlecPeirceScuba_SeaHunter]

No thanks. You should see my big tools. Check out my "At The Ranch" channel for farm and home projects. A.

[@scubaclient355]

I think you forgot to mention the different valve threads.

[@AlecPeirceScuba_SeaHunter]

That is in an future video SC.

[@SeattleRingHunter]

6:49 I proudly disagree with the manufactures procedure! Please people NEVER smack your valve handle as indicated! The point was made clear lightly tap, not hammer, as not to stretch the tank threads. You wold be better to put a flat wrench on the actual flats of the valve and with a bare hand fist bumpy the spammer ever so softly until the top surface of the cylinder mates flush against the valve shoulder insuring the o-ring has been adequately compressed as intended by the engineering design. Do as you wish but I’m not smacking my valves that’s idiotic. Cheers, #SeattleRingHunter

[@AlecPeirceScuba_SeaHunter]

Remember that i read Catalina's manufactures actual instructions and did not make it up. A

[@SeattleRingHunter]

@@AlecPeirceScuba_SeaHunter Correct I take umbrage with the manufactures written procedure. We technician types also understand what they intended to convey but we also never underestimate what new less than mechanical minded individuals are capable of doing from this type of instruction. Shocking really as the rotating valve shafts were never intended to take any type of impacting blows. Next thing you know you have DIY recreational divers smacking the crap out of these new plastic pro valves knobs with the red and green plastic indicators. One thing leads to another then a broken knob potentially. Really people need to be refocused this is life support equipment that needs to be respected accordingly. Heck with all the efforts we drill for in rescue class we ought to be told to be highly suspicious of new green divers these days more than ever. The underlying point is more and more gear these days are easily ordered in pieces due to price shopping and self configured by new divers that may not have enough technical skill to changer their own flat tire but opt to configure their new dive gear on their own to save some money. In my initial dive training we had an adult lady show up for open water with her her own kit her husband had pieced together the night before. A high pressure hose from her gauge set came loose and was whipping around her head as she was about to go chest high in the water. Fortunately she didn’t get her teeth smacked out and one of the instructors quickly reacted to close her tank valve. I also don’t want to sound cocky as I fully realize any of us are capable of an oversight regardless of experience level. The manufactures instruction just happen to take me by surprise they would even suggest such a practice. Sure 99.9% of the time a light bump from the hand won’t harm a valve knob but star suggesting a mallet and that is where I lost all respect for that instruction where there is perfect flats machined to the neck of the valve for use of a proper spammer for said purpose.

[@hosertee]

Why isn’t it called a gas cylinder valve?

[@AlecPeirceScuba_SeaHunter]

All scuba tanks valves are technically called that. However, because we go underwater vs a fireman's gas cylinder, these are generally referred to as 'scuba tank valves' for clarity purposes.

[@hosertee]

@@AlecPeirceScuba_SeaHunter thank you, seems like tank vs cylinder is used interchangeably was wondering if there was a specific reason for the use of tank in this case for a "k valve" :)