Scuba Tank for silent DIY shop compressor

[The Chairman]

FWIW, as loud as compressors are, many of the tools driven by them are far, far noisier.

 

[ofg-1]

Using a scuba tank is not difficult, use a steel tank, drill and tap a hole in the bottom of it and install a drain valve. You can probably get one that has failed hydro, or has rust. Remember, at 250psi, scuba tanks really do not hold a lot of volume, and the compressor will run a lot depending on the tool.

You want quiet, just put a real compressor in a dog house out in your back yard, pipe it into your shop.

 

[rddvet]

Using a scuba tank is not difficult, use a steel tank, drill and tap a hole in the bottom of it and install a drain valve. You can probably get one that has failed hydro, or has rust. Remember, at 250psi, scuba tanks really do not hold a lot of volume, and the compressor will run a lot depending on the tool.

You want quiet, just put a real compressor in a dog house out in your back yard, pipe it into your shop.

How's the dog going to get any rest

 

[ofg-1]

How's the dog going to get any rest

Ours sleeps on the couch, doesn't everyone's?

 

[Brian G]

As you can see, many folks don't get why you might want to DIY something that can be easily and/or cheaply purchased. Scubaboard has a DIY forum that avoids some of this. About your project, certainly a scuba tank will have no issues with 300 psi. An aluminum tank will probably last forever, but even a steel tank will take many years to rust through given that there shouldn't be too much salt in the water from compression. Most power tools are designed for a particular pressure, so if I were doing this, I'd use a cheap scuba first stage as a regulator. Diaphragm first stages are usually easier to adjust down to 90 psi, so I'd use an old Conshelf 14 through 22 or Aqualung Titan/Micro/Legend. Ok, I'd actually use an old Scubapro Mk11 because that's what I use for scuba and I'm used to those. I would just drill some new holes in the tank for a drain and the inlet. I'd love to see pics if you get this complete!

 

[kelemvor]

OK, it's for shop tools. Which shop tools? The problem with shop tools is that they not only need pressure, but also volume. A 3/8" air ratchet can consume 5 cfm@ 120psi. A great 1/2" ratchet will need 7 cfm and something like a DA sander can go all the way up to 20 cfm. I just don't see a compressor off of a refrigerator producing more than a one or two cfm and that free tank is probably less than 2 cf of buffer. OK, so a brad nailer uses a half cfm, so that's limiting you to that and filling a tire or two.

scfmgate

What's worse is that "home" air compressors (i.e anything sold at retail stores such as home depot) are rated in scfm. That "s" means they only put out the rated CFM at 0psi load (i.e. with no tool attached) so if something needs 5cfm@120psi you ain't gonna do it with a home air compressor. Well for the most part. You can get real compressors such as this on big box websites. $800 for a dewilt from home depot. That one will do 5cfm at 90psi but not 5cfm at 120psi.

Unfortunately, I bought several air wrenches before I figured it out... now they're just collecting rust.

Here's a video on the subject.
An al80 is only going to hold about 3.2cuft of gas at 120psi and 8cuft at 300. That's not a lot of reserve if your pump is only producing 1cfm.

 

[tbone1004]

@Brian G I'm all for DIY and have don ea lot of DIY stuff. My problem is where it isn't practical.

This is in stock at Lowes in Hawaii for $209. An AL80 holds about 3 gallons of water. So here for less than $250, you have a compressor with a comparable reserve size, rated at 2.4cfm @90psi which is more than 2x the capacity of the fridge compressor, and is fully put together. The noise is significantly quieter than any air tool since this compressor is the same design as what is used in at-home O2 generators for people that need to be on oxygen. You can easily hold a normal conversation around it and the volume is comparable to being near a modern car that is idling. It's there, you know it's there, but it's not offensive by any means. The cost of fittings alone to do what the original concept was is likely to exceed that of this compressor and you trade off portability and capacity for a marginal improvement in noise.
When compressors like this are on the market, the fridge pump thing is a project for the sake of doing the project vs. one that is actually practical
https://www.lowes.com/pd/Kobalt-Qui...Electric-Twin-Stack-Air-Compressor/1001022908

 

[The Chairman]

Again... without knowing the tools he wants to use, we can specify just about anything and it only has a slim chance of being suitable. I have a tiny little airbrush compressor. It couldn't even run a nail gun. But then again, my shop air is not suitable for a tiny little airbrush without a separator and a suitable regulator. Match the compressor to what you want to run, not the other way around.

 

[tbone1004]

@The Chairman speaking of, when are we getting your big shop compressor up and running? That'll make boosting much more practical when I come down in September compared to my tiny little thing....

 

[The Chairman]

@The Chairman speaking of, when are we getting your big shop compressor up and running? That'll make boosting much more practical when I come down in September compared to my tiny little thing....

The cement mixer I ordered has a broken ring gear. Waiting on a new one. The form for the 6x10 slab has been set and I'm ready to pour. Grrrrrrrrrrr.