Removing Valves and Installing a Manifold

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Vegan Shark

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Okinawa
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I just don't log dives
Are there any video tutorials to removing existing valves on tanks, and installing a manifold for doubles? How easy is this to do, what can go wrong, etc?
 
pretty easy, what can go wrong is bending the manifold....

You should be at a shop to do this so you can pressurize them relatively quickly.... or at least around a compressor or a transfill whip.

Process #1 is basically as follows. DiveRite has a video that I'm trying to find, but here's how to do it.

Assemble manifold. Make sure you are twisting the crossbar not the valves so it is evenly spaced between the tanks so it can be adjusted down the road. The dipsticks should be 8.5 inches apart per modern manifold standards. They are reverse thread so you can spin the middle like a tootsie roll. Make sure all three valves are wide open, obviously don't torque them open, just open until they stop.

Drain tanks, remove valves. Might require a dead blow hammer, but usually whacking it with the palm of your hand will get it to move.

On a tower preferably on a sturdy table, slide the tanks into the bands with the hardware nice and loose. It helps to have a second person to do this but it is possible with one. Hold the manifold so the valves are in both tanks, and spin the first one in until the threads grab, make sure not to cross thread, they should spin very easily. Once the first one is in a few threads, start the second one so the manifold is stable, then screw both tanks all the way in. They don't need to be in there super tight, but should be pretty snug. Shut the valves after the tanks are both screwed all the way in. Adjust the manifold if need be, but if you set it to 8.5" center it shouldn't need it.

Once both tanks are in, set the top of the bands just below the crown on the top and tighten them down, you want these pretty snug. Put your wing and plate on the top band and slide the bottom one around until it hits the hole. If your plate has multiple holes make sure they are in the same ones, top to top, middle to middle etc. Once the bottom band is set, tighten on down, and go fill em up. Do not do this outside in a humid area, the tanks should be room temperature in a dry environment when you do this to prevent any condensation from building up. These bottles will no longer be O2 cleaned, so keep that in mind.

Process #2 is the other school of though. That is to install the valves without the crossbar, then lay them next to each other and spin the manifold in at the same time on both valves. If you do the first process properly or if it is already assembled from the factory, then you're good to go. After the manifold is on, slide the bands up and tighten as above. I think this one is very awkward, and if you grab the thread on the above process and put it on x-number of full rotations, then do the same with the other side, then spin them on together it does the same thing and is much easier for me to not worry about bending the crossbar.
 
I'm not aware of any videos (but I haven't looked, try YouTube)......but it's a piece of cake and little can go wrong if you're careful. The biggest problem I've had with it is the tanks wanting to fight eachother and try to bend the manifold. What I found was easiest to do was to do it one of two ways:

1) Put valves on tanks, no manifold. Screw manifold into both tanks simultaneously until desired width (determined by bands) is achieved. Slide bands over manifold (without bolts, obviously) to desired location. Install hardware, go dive.
2) Assemble valve/manifold unit. Slide both tanks into the bands. Adjust manifold/valves to proper width. Spin the tanks into the valves. Dive them.

Removing the valves is as simple as bleeding ALL of the air out of the tanks and spinning the valves off. Only danger there is any residual moisture in the tank can be pretty bad in that it can be hard to remove and quickly rust the inside of the cylinders. Bleed the tanks slowly, preferably in an A/C environment (humidity controlled), rebuild them soon, and get them filled as soon as is practicable.
 
It would be a good idea to get VIPs done on the tanks before putting the doubles together. They have to come apart every year for inspection so it saves time if you start with a fresh VIP.
 
depends on how close to vip they are, if they aren't all that close it doesn't make sense if you're not O2 cleaning them, the shop will break them down. For VIP without O2 cleaning it's super easy to just break spin them out of the valve one at a time, look into them, then spin them back in
 
Thanks, everyone! Few more questions.

1. So, to remove the valves, and put in new ones, you can just tighten/untighten with your hands, no tools necessary?

2. Do band sizes need to be exact? Tanks I'm looking at are 188mm in diameter, vs 190mm in diameter (around 7.5"). I'm assuming 2mm won't make much of a difference?
 
1. It MIGHT require tools, but a piece of wood or soft mallet are the way to go.

2. 2mm shouldn't matter, but the sizes should be VERY close and they DO need to be exact. That 2mm is probably just enough to let you slide tanks in there.
 
I do not like using a mallet or anything really to tap on a valve. Seen a few where someone bent a handle like that.

A big crescent wrench is better. I have over a dozen tanks and use a wrench. A big wrench will give you enough leverage to spin off the valves safely.

I actually cut a couple on the waterjet out of 3/16 brass plate to minimize the damage potential even more.

Same with tightening them. Spin on by hand, use the wrench to tighten down, and a smack of the hand on the wrench is enough. Using a mallet or block of wood is just too risky for me.

Valves are relatively inexpensive, but a dozen or more start to add up.
 

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