Pressure in a compressor tank: temporarily "forcing" higher pressures

Jan 10, 2013 12 Replies

Awl --



In my otherwise fairly-impressive Husky compressor, the s***ty regulator has it cycle between 80 and 120 psi -- which I (and my machines) can live with, albeit grudgingly..



But occasionally what I would like to do is "force" the pressure up to mebbe



130-140, to, for example, nicely charge my small HF portable air tank (for tires, basically).

What I do now is have the portable tank ready, and when I hear the compressor start up, fill the tank, so it will at least be filled at the shut-off pressure of the regulator (120 psi). Instead of, say, 80 psi if I just fill it willy-nilly. Catching the compressor when it is "on" is its own timing pita.



Can I do this by just jumping the motor relay? Or would the unloading valve allow me to do this only when the compressor is already running? Or am I off base altogether? I suppose I could just adjust the regulator with the screw when I need higher pressure, but that's a pita as well. Heh, mebbe put a C clamp on it? LOL



Idears?


I looked into that, either with a switch in parallel or a valve on the air line to the control plus a blow-off valve in case I'm distracted, and concluded that a small 12V compressor that can reach 200PSI was a more versatile and safer solution.

This filled the flat tire on an old car way back in the woods faster than we could have done it with long extension cords and air hoses, or carrying a tank back and forth which the owner was also doing as I was unsure the untested power pack was enough.

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Its 400W inverter can run a Milwaukee 1/2", 5.5A drill though I could trip the overload by holding the chuck tightly.

I carry this smaller, cheaper unit in the car:

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I wasn't inpressed by the low-end ones but so far the MF-1040 has worked well and stood up to banging around. Its coiled hose with quick-disconnect and brass screw-on tire valve fitting is a considerable improvement on the integral rubber hoses that break. I use the higher pressure to top off water-filled fire extinguishers. jsw

Hmm, Maybe if you cycle the power to the compressor it would reset to it's 'recharge' state. I'm pretty sure there must be someway to 'jimmy' the thing into the recharging state... but then you are playing around with AC relays. (I use my old sears compressor so rarely that it's always unplugged.)

George H.

Hmm, Maybe if you cycle the power to the compressor it would reset to it's 'recharge' state. I'm pretty sure there must be someway to 'jimmy' the thing into the recharging state... but then you are playing around with AC relays. (I use my old sears compressor so rarely that it's always unplugged.)

George H. ===================================================

Right..... by "re-charge state" you actually mean letting the compressor fall below the low setpoint pressure, upon which it charges to the high setpoint. That's what I was referring to by "catching the compressor when it's on".

So I spose when I want to fill my portable, and the 'pressor is at, say,

90#, I could just bleed off air, until it starts cycling.... But how *barbaric* is DAT??? LOL

Is the "air pig" rated for 140psi???

I was just going to suggest pulling the ring on the pop off valve myself.

I bleed air on my compressor all the time from the ball valve I installed in place of the bleeder valve anyway. Keeps the water out of the the tank that way. I have drain valves on the bottom of all my air manifolds around the shop too. Nothing wrong with bleeding air.

IF IF the tank is safe for max pressure.. Just get a one way valve, and let it stay connected to the compressor. It will fill to the max pressure that the compressor achieved.

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I use purged bbq bottles as air pigs with removable adapters attached to the propane valve.the adapter consists of the propane fitting, pressure gauge, schrader valve and female quick connect. When filling the pig, I use a double ended male quick connect and when the compressor reaches high cut off, I close the tank valve anddisconnect from the source. I have half a dozen full tanks in the shed which I re fill occasionaly. I also use these to extend the time between recharge breaks.

Oh sorry, I don't have an air pig.

George H.

Here ya go. Either make one or buy one. They are truly handy to have.

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$25

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$38

Videos to make one:

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Leave one hooked up to a spare connection on your main compressor for extra air capacity and it will be ready whenever you need it.

I made mine out of the A and B component tanks for urethane foam. The inside is coated with nylon so I don't have to worry about them rusting out. They're about 38 years old now. (Hmm, I think it's about time for a fresh paint job on 'em.)

Years ago, I got a 3 gal pancake compressor. Inflating tires, and other small duty jobs. Doesn't have enough air to run air wrench. So, I'd been thinking to plumb on an expansion tank like that. I still plan to, and havn't yet tried it. A friend has a "5 HP" compressor with 20 gal tank which I've used. I question the 5 HP rating, but it did a nice job.

Christopher A. Young Learn more about Jesus

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Here ya go. Either make one or buy one. They are truly handy to have.

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$25

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$38

Videos to make one:

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Leave one hooked up to a spare connection on your main compressor for extra air capacity and it will be ready whenever you need it.

I made mine out of the A and B component tanks for urethane foam. The inside is coated with nylon so I don't have to worry about them rusting out. They're about 38 years old now. (Hmm, I think it's about time for a fresh paint job on 'em.)

Good. The bacon is mighty thin on them, and the hams are nonesistant! ;-)

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