Building a tank dryer

[jormax]

I have several steel tanks and they often have light rust in them when I VIP them. I have been either having them tumbled or whiped, but I would like to whip them myself and then wash them out and dry them. I have seen tank dryers at GMC for about $350 but think I could make one myself for less. Any plans or articles out there?

 

[Packhorse]

Make a holder for it so it is upside down. Get a LP reg hose less the reg and shove it up the tank and drain a full tanks worth of air into it.
May cost you an air fill every time you do it but the rest is free!
Make sure you cap the tank after as it may get cold and attract condensation.

 

[skdvr]

I too am looking to build something to rinse and dry tanks. Al though for $85 you can buy one of these. I have used these at my LDS to rinse the tank and then have an air gun attached to a LP hose off a tank reg (make sure it is O2 clean air, NOT from a shop compressor) and then just detach the hose that is on the tank stand from the hose suppling the rinse water, attach the air gun to the hose on the tank stand with an O-Ring and let it blow good clean air in for a few min. If you rinse with hot water it will dry very quickly. I get no flash rust when I rinse my steel tanks.

I will try and explain the way that I attach the air gun to the hose. There is an O-Ring around the hose and when I put the tip of the airgun into the hose I pull that O-Ring up and over the hook that is on the front of the airgun and that keeps it inplace. Then I use another O-Ring or rubberband to keep the trigger squeezed so that I do not have to stand there and hold it while the tank is drying. Hopefully that makes sense. If not I can try to get you a pic...

If anyone has any plans for a DIY rinse/dry stand I would love to see them....

Phil

EDIT - Just to clarify my statement above about the shop compressor. What I am saying should not be used is a compressor that is used to fill car tires and run air tools. Obviously a compressor used at the Dive Shop for filling tanks is perfectly acceptable to use. Anyone that is O2 cleaning tanks should know what I meant, but I just wanted to clarify...

 

[Cave Bum]

That's about what I built for my stand and used a heat gun under it to finish drying the tank. Use of hot rinse water makes it dry quicker and more completely. I made that drawing from memory but I'll check the acutual dimensions this weekend and post a complete set of instructions in the 'how to' section of my web site on Monday.

I used 1 1/2" perf galv angle and 1 1/2" perf galv flat just because I had it laying around. I built a 12" x 36" base with 3" welded rings for the tank neck and a 12" x 36" 3 sided top for the tank to lean against. The legs were (I think) 21 " long.

One other trick I use is to sandblast the inside of steel tanks instead of tumbling them. I use the 40 lb Sandblaster from Harbor Freight and aluminum oxide grit. It works quicker and better then tumbling or the whip they sell.

 

[Gilldiver]

If you only do a few tanks at a time there is no need to get any elaborate system. Here is all I use for all my tanks aluminum or steel:

And here is a 40 being dried.

The key is to use hot water, as hot as you can get it from your water heater. Get the tank hot to the touch so that you need gloves to handle it. Then quickly pour out the water, place the pipe coupling on the tank neck, and place the electrical conduit bend into the neck of the tank. Flip it over and give it a blast of air from a tank for 20 to 30 seconds through the conduit.

Check with a light for remaining water and give it a second blast if needed. I have never needed a third blast.

The drying action is so fast that you do not get flash rust and you can not get near the danger temps of aluminum heat treatment with water as the hottest you can get water is 212F vs, heat treatment temps of 250-350F.

Total cost for the drying equipment is less then $5 not counting the tank and reg for the compressed air.

 

[deepstops]

There's a shop in Ozark, AL that does it best, they blow the tank dry using nitrogen.

No oxygen, no rust.

 

[dave4868]

Like Pete (Gilldiver), I use a hot water rinse followed by drying with compressed scuba tank air.

I find the tank will dry more quickly and evenly if the drying gas is injected through a long perforated tube which has been inserted into the tank.

The tube is made from about 20 inches of 3/8" ID polyethylene tubing into which I've drilled about forty 1/8" holes in the sides and one hole in a wooden plug placed in one end of the tube.

Since my tap water is quite high in minerals, especially iron, my tanks were prone to light flash rust, even when dried quickly.

My compromise method is to turn my hot water heater up and rinse the tank with about 140F tap water, followed by a quick light rinse with about a quart or two of distilled water sprayed under high pressure from a fire extinguisher through another perforated tube.

Then the tank gets a dose of an 8 oz solution of Compound "O" rust inhibitor, followed by agitation or rolling on the tumbler for 3 minutes, then drained. It is then quickly rinsed with distilled water for 5 to 10 seconds, then blasted with my perforated air wand for about 3 minutes, using up about 15 cubic feet of tank air.

Since my tank has cooled off quite a bit, it doesn't dry as fast as Pete's arrangement, but at least I'm keeping the flash rust at bay!

Dave C

 

[skdvr]

Gill - I love the PVC Pipe stand... I think that I will use that... How do you get the tumbling media out of your tanks... I am a bit spoiled by my LDS because they have a huge pipe vise that will hold the tanks upside down and then I beat the tank with a rubber mallet to get the media out. Although at my LDS I am using ceramic chips (which can be a bit of a pain to get out) and for home I bought some glass beads so they should be much easier to get out, but I have not used them yet...

Phil

 

[dave4868]

Gill - I love the PVC Pipe stand... I think that I will use that... How do you get the tumbling media out of your tanks... I am a bit spoiled by my LDS because they have a huge pipe vise that will hold the tanks upside down and then I beat the tank with a rubber mallet to get the media out. Although at my LDS I am using ceramic chips (which can be a bit of a pain to get out) and for home I bought some glass beads so they should be much easier to get out, but I have not used them yet...

Not to cut Pete (Gilldiver) out, but let me suggest a real labor-saving method: invert the tank in any kind of homemade stand and use a jet of water to help gravity eject the media. See pic below.

My arrangement is to place the tank neck-down in a Pelican wire tank rack that is propped on a couple of 5-gallon plastic buckets with a pan or bucket under the tank to catch the media. Then, using a curved section of 1/4" ID aluminum tubing attached to a garden hose nozzle, I insert about 2 inches of the tubing through the media in the tank neck and inject water for a few seconds, then remove the tube quickly. The pressurized water loosens and then ejects a quart or two of media over the next few seconds until it slows down and jams again. Repeat the water injection about 10 to 20 times and even 40 lbs of aluminum oxide chips will be totally removed from the tank in less than 5 minutes.

By the way, in the picture you can see the curved aluminum tubing attached to a short piece of washing machine hose which is screwed onto the garden hose nozzle. The media are ejected into the bucket beneath the tank and then transferred to the sieve bucket in the background for further rinsing. The blue rubber pan under the sieve bucket has a drain fitting with an attached garden hose to transfer the waste water.

The rack is also used when I dry the tank.

Most items courtesy of my local dump.....

Dave C

 

[Gilldiver]

How do you get the tumbling media out of your tanks...

After 30 years of diving I have found that the use of Shop Monkes is Justified at some point. Tumbling is one such point.

I have also found that if you take care of your tanks and have your own tank whip, you can get out 70-80% of any rust or corrosion. Hint, a large drill press works well for stubborn spots. Set the whip up, clamp the tank in and let it run for 10-15 minutes.

Also, Teaching your 8-10 year old the use of the tank Whip is not child labor but is justified as "Learning the Ropes" for a potential new diver. However, it may annoy the wife/mother of the kid.

Pete