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Valve to fill additional compressed air tank

I have a strange sounding idea. I want to have an extra compressed air tank in my system. I have a bunch of tanks at this moment to choose from. This way, I could run air hungry tools like breakers, etc, intermittently but longer.

So far, so good, and nothing complicated. I have a whole bunch of tanks right now, and thought to do something nice for my shop and have an extra tank.

Examples of tanks I have are:

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(Tank with "QT-15" lettering on left)

However, I also realize that with a big extra tank, it will take so much longer for the air system to come up to pressure. This will be my wasted money, as people will be waiting longer to use compressed air.

So, I thought, can I have a valve, that would not fill the tank, until system pressure reached 120 PSI. And then it would shut off again if the pressure ever falls to below 90 PSI.

To use the accumulator tank to supply air, another pipe would be used with a check valve.

This setup makes sense to me, as

1) I would get the system to reach pressure quickly and 2) I would eventually get a supply of air in the accumulator, without ever dropping the system pressure below 90 PSI.

I do realize that I can accomplish what I want, with a electric pressure switch and a normally open pneumatic valve. But I thought, perhaps, there is a purely pneumatic valve that does this? What would it be called?

Reply to
Ignoramus5722
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Add compressor capacity, rather than tank volume, presuming you have a reasonable size tank now. Set the pressure switch for the second compressor to come on as say 10 psi below the first's cut in pressure so it will only come on when the first is unable to keep up with the demand.

Reply to
Pete C.

Ignoramus5722 fired this volley in news:EIadnai6nY3T4z_PnZ2dnUVZ snipped-for-privacy@giganews.com:

Ig, you're mistaken about people "waiting for air". Unless their net usage is higher than the pump capacity, the pump will come on when the combined tanks get to the desired cut-in pressure, and shut off when they get topped off, just like they do with smaller tanks. The difference is, that they can use air-hogs longer before they have to stop.

The total duty cycle will remain approximately what it was before. The pump will stay on longer, yes; It'll also stay off longer.

You don't need _any_ valves to accomplish what you want. You're over- thinking it.

(although you should provide manual valves to isolate tanks, in case of a leak or a service issue)

Lloyd

Reply to
Lloyd E. Sponenburgh

We do not have the compressor on at all times. We turn it on in the morning or when it is necessary.

Exactly.

But when we turn the compressor on in the morning, when we need air, I do not want to wait extra 15 minutes.

No,I do need that for start-ups.

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Reply to
Ignoramus5722

"Pete C." fired this volley in news:52a27f48$0$47806 $ snipped-for-privacy@ngroups.net:

Yep, Ig. Remember, no matter HOW large your tank, you can never use more air per minute - on average - than your pump will supply.

LLoyd

Reply to
Lloyd E. Sponenburgh

Pete, I would like to explore my idea in the original post, for now. I do not really want to get more compressors, for now. Even though it is tempting to upgrade,I just bought a 15HP Quincy 370 compressor. My shop guy wants me to upgrade my 10HP quincy to this one.But I do not want the hassle of upgrading the wiring and dealing with a messy wiring duct.

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Reply to
Ignoramus5722

... But I thought,

It's a pressure relief valve. With an exit port, not just venting to air. The tricky part is finding one with an adjustable differential, so that it could be made to stay open until 90 psi. Bob

Reply to
Bob Engelhardt

Lloyd, and Pete, I appreciate your opinion and I do understand that I cannot get more compressed air per hour with an extra tank.

But, I want an answer to my originalquestion,as I do see a big benefit in what I want to accomplish.

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Reply to
Ignoramus5722

Ignoramus5722 fired this volley in news:otedncjqdtJ9GT_PnZ2dnUVZ snipped-for-privacy@giganews.com:

Ok... just put a uni-directional flow-control valve (with a ball check in it) between the 'main system' and the reserve tank. Control the flow (slow bleed) INTO the reserve tank, but let it back-flow freely into the main system any time its pressure is greater than the system.

Then the main system will pump up _almost_ as fast as it would without the reserve, slowly bleeding air into the reserve as it goes. When sudden demands occur, the reserve will freely feed the whole system.

Such valves are purely mechanical, one-piece assemblies... ball-check and flow control (often needle type) valve in one unit.

Lloyd

Reply to
Lloyd E. Sponenburgh

Bob Engelhardt fired this volley in news: snipped-for-privacy@news6.newsguy.com:

That doesn't solve the filling part, only the 'feeding' part.

A one-direction flow control valve will do both.

Lloyd

Reply to
Lloyd E. Sponenburgh

"Lloyd E. Sponenburgh" fired this volley in news:XnsA28EDA68C8DBlloydspmindspringcom@216.168.3.70:

Here's one that'll do 83scfm in the free-flow direction, and the schematic symbol.

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LLoyd

Reply to
Lloyd E. Sponenburgh

"Lloyd E. Sponenburgh" fired this volley in news:XnsA28EDBA34F820lloydspmindspringcom@216.168.3.70:

Oh... that one is a poppet style, not ball-check, but I've used that model, and they last for years and years.

Lloyd

Reply to
Lloyd E. Sponenburgh

Yeah, it does: the relief valve "in" is connected to the basic tank and the "out" to the auxiliary tank. When the basic tank reaches 125, the relief valve opens & delivers air to the aux tank.

Unless I'm missing something, which wouldn't be the first time.

Bob

Reply to
Bob Engelhardt

Bob Engelhardt fired this volley in news: snipped-for-privacy@news4.newsguy.com:

And when that 90psi relief valve opens, it supplies 125psi MINUS 90 to the reserve -- 35psi. And how's all that 35psi air going to get back to the system FROM the aux tank when needed?

A simple check valve with one-direction restriction fixes the whole problem -- both ways, and without any pressure differentials (well, a pound or two).

Lloyd

Reply to
Lloyd E. Sponenburgh

On 12/6/2013 9:51 PM, Lloyd E. Sponenburgh wrote: ...

Oooh ... yeah. Feeling dumb, Bob

Reply to
Bob Engelhardt

Lloyd, I thought a lot about this, and I think that it is the best solution because it is so simple, and also is friendly to the air dryer that would be between the compressor and the additional tank.

Thank you. I Saved your suggestion. I will talk to my shop guy and if I put in the second tank, I will use this valve.

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Reply to
Ignoramus5722

So isolate a smaller tank before the large and use a ball valve to shut down the main tank and use the smaller one for quick air needs. It could easily be valved both to the compressor and to system air, with a single line for your immediate use. Keep the little guy filled and only open him when you need a dustoff.

Reply to
Larry Jaques

Bob, does that valve waste a lot of energy, meaning does it have a big pressure drop?

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Reply to
Ignoramus5722

If you find a good solution, please let me know. I bring a tractor PTO compressor out to the field every day. I could reduce the tractor RPM (save fuel) if such an accumulator could be designed.

I've thought of adding a couple old 100 lb. LP bottles but don't want to wait for the whole system to build pressure before starting. The shears need 100 psi to work so you can't start until almost to cutout pressure.

Karl

Reply to
Karl Townsend

Karl, I am still thinking. Yesterday I thought to go with what Lloyd recommended, a flow control valve. Then I realized that it is not as good as I want. There is an energy loss and also the system will not come up to pressure fast.

Nw I am leaning towards a system with a check valve for air outflow, and a pressure switch controlled solenoid valve for filling.

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Reply to
Ignoramus5722

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