Air tool question: damage to pressure regulator?

[Gator81]

Please read the whole thing before you reply. I'm not real good at being concise.

This is an air tool question, not a boat question, but I know someone here knows the answer.

I have a typical compressor in my shop, maintaining 125 psi. I use a little 5-gallon portable tank as a way to use air tools when dragging a long air line isn't practical. It's great for when I need to do a little paint work or use an air tool that doesn't take a lot of volume, like my 18ga brad nailer, doing wood trim and moulding work. The 5gal of air at 125 psi will let me shoot 100 nails, easy. I have a regulator on the tank. I usually run my HVLP paint gun at about 40 psi and my brad nailer at about 60 psi.

Here's the problem. The portable tank has a simple tire-type inlet valve for filling. So, I have to use an inflator on my shop's air line to fill the tank. Takes a long time, and I have to hold it on there. I'm thinking, this tank also has a female quick connector for an outlet, where I hook up the tools. Why not simply make myself a little hose with male connectors on both ends? One end goes on the shop's compressor, the other on the tank's outlet. It would speed the refilling of the tank way up, and I wouldn't have to hold it on there like the inflator. But if I did that, I would be filling the tank by pushing the air in through the regulator, backwards.

Here's the question: Will I damage the pressure regulator by pushing the air into the tank backwards through the regulator? What if I open up the regulator so it's at the same 125psi level as the source while the portable tank's being filled?

Sorry to be so wordy. Thanks for your thoughtful replies!

[delmarrey]

Plumb in a "T" fitting between the regulator and the tank and put on a female fitting like the one on the end of the air hose. Make an adaptor with two male fittings with a ball valve between them and use that for the feed line. Shut off the ball valve when connecting or disconnecting.

You can also use the extra fitting for a hi pressure blast if you need it (air gun).

That's it......................................_/)

[Alan Wheeler]

Yeah and just to stretch out what Del said or didn't say, the regulator locks off the flow in reverse. So you can't fill via that way.

[delmarrey]

Actually, if you wanted to save fittings you could put the ball valve between the "T" and a male fitting, & not have an adapter. It's just that it might stick out a bit, but if you can handle that it would work by just plugging your air compressor in to the male fitting then open the valve. When they are ambient then close the valve and disconnect.

Just don't bump the valve while working. And you'll lose the capability for the air nozzle fitting. So what ever is convenient.

EZ as pie................................_/)

[Gator81]

Thanks, guys. I suspected that was the case. Adding the extra connection w/o regulation was the obvious solution, but I just thought I'd see if I could take the lazy way out... One-a-these days, I've got to open up an air regulator and figure out how they work.

Another advantage of that is, when not in use I can leave the tank connected to the shop system, so it's always full and ready to go.

[Alan Wheeler]

A regulator is a rather simple device. It uis a rubber diaphragm, a spring and a pin that acts as a valve. The spring pushes the diaphragm one way opening the valve seat and air rushes through. As the air builds up pressure on the other side of the diaphragm, it pushes back on the spring and the valve closes. The spring tension thus sets the air pressure the two will equalize at. So in your case, pressure on the opposing side of the diaphragm would result in the valve seat being pushed closed.
I would have a "T" on the tank as Del suggested. The regulator on one end for your tools and a quick release on the other.

Like this............... regulator-- T --quick release
..........................................Tank

[delmarrey]

Originally Posted by Gator81

Another advantage of that is, when not in use I can leave the tank connected to the shop system, so it's always full and ready to go.

It also helps reduce power consumtion. Large air vessel's are used in the industry to aviod start-up's. The start-up is what draws the amps, increasing the the power bill plus the ware and tear on the compressor.

As for air reg's all it is, is a hollow area with a diaphragm thru the middle. On one side of the diaphragm is a valve seat, which the air flows thru. On the other side is an adjustable spring.

By tightening the spring it regulates the amount of air pressure it take to open the valve................................._/)

[hellosailor]

The "tire" thing is called a Schraeder Valve. The valve core unscrews very easily, using a 50c tool or the top end of a valve cap that has two nubbie bumps on it--which is what the business end of the tool is.

If you unscrew the valve core, you now have a "pipe" going into the tank. With a hose clamp and some air hose, you can attach anything you please to that--including any convenient quick disconnect ("qd") fitting, on a "t" with another Schraeder valve, if you choose.

Neater to "T" in before the regulator, but if you don't use the schraeder valve...you don't need to keep it. (And you can always screw the valve core back in to use it again.)

Leaving the portable tank connected to the shop compressor all the time might be a danger. Compressors tend to accumulate moisture and those portable tanks sometimes rust out in a rude and sudden manner. Unless you've got one designed for "permanent" use rather than occassional?

[Gator81]

See? This is why is ask questions! (< that's me!) I haven't given anyt thought to problems associated with leaving the tank on the compressor outlet line all the time.

The tank is a common Campbell-Hausfeld 5-gal portie. I don't recall ever reading anywhere whether it was considered for "occasional use" only. But I do know that it does NOT have a drain valve. There is a spring-pin release valve on the main outlet (on top of the tank), and every once in awhile, when the pressure is way down, I tip it upside down to let any moisture run to that point, and then pull the release valve. The air coming out then feels a wee bit damp, but no visible liquid moisture so far. I think that's because the main compressor tank catches it all. I'm also in a very dry climate (Utah), but I still get enough water in the main tank that I need to drain it probably once every week or two.

That portie has an "expiration" date on it, saying it should be discarded in 2010. I bought it in 2005.

One of the hassles of all this is that I have to piece it all together, with little brass nipples and elbows and Ts and such. It gets to be awkward and seems accident-prone. You'd think somebody would make an all-in-one deal for these tanks, with regulated and non-regulated QD's as well as a Schraeder valve (thanks for the vocab!). Maybe one of you recreational engineers needs a project for your spare time...