Air Compressor - Supe'ing Up Question

[Angello Huong]

I have a single-stage 2 HP, 8 gallon Central Pneumatic air compressor that I've supe'ed up.

The pump normally turns on at 80 PSI and then shuts off at 115 PSI. Problem is, at 80 PSI (before it turns on again), my nail guns don't drive the nails flush. I need it to have a consistent minimum 100 PSI going through it.

I have increased the pressure switch so that it now goes from 100 PSI cut-on and then 135 PSI shut off. I know that it will likely reduce the life of my compressor in the long run, but does anyone know how much difference a 20% increase in pressure reduces the working life of a pump? I only use it for a few hours a year, so the compressor doesn't get a lot of regular stress put on it. Plus, it's not too expensive, so I can just buy another one. So this is more of an educational question.

I've heard that all 2 HP (and up) pumps (single and 2 stage) are capable to doing more than 115 PSI. Maybe the 2 stage can do it with more CFM and with a longer pump life.

Also, I'm thinking about connecting it in series with a separate 10 gal. air tank, so that I can have a total working capacity of 18 gal combined.

Is this too abusive to be doing to my poor 2 HP motor? In theory, if I let it have several minutes of rest and cool-downs between engine cycles, it should be ok, right?

Angello

[Tony Hwang]

Hi, Safety first! I double your motor isreal 2 HP rated.

[Bob F]

You

[Hustlin' Hank]

You'll probably be ok. But, the first consideration is the tank not holding up under the higher pressure. Is it rated for 135 psi? If not, it may blow! LOL

Also, Tanks build up moisture and begin to rust on the inside. When the rust is bad enough it will leak and maybe explode.

Since your compressor will be running longer to build up more pressure, you wil undoubtedly create more heat for a longer period of time. Who knows how that heat will affect the seals, gaskets and etc.? More load on the motor will also create more heat on the motor. Again, who knows how the bearings, windings will hold up?

Attaching an extra tank will only make the compressor run longer which means it will be subjected to longer periods of heat. But, it will give more capacity.

Bottom line: All this doesn't matter since you are ready to buy a new when it burns up because they are so cheap anyway.

roflmao

Hank

[salty]

Beat it until it quits and then buy the bigger compressor that you should have bought in the first place. Next time buy one bigger than you think you will need and grow into it.

[BQ340]

Also check your air hose. Small diameter hose & using restrictive fittings will cause that problem.

MikeB

[Joe]

Second that motion. Get a set of Milton V fittings for your hoses and you'll nearly double air flow.

Joe

[gfretwell]

To start with I bet this isn't really 2HP, what does it plug into (120v?). My 1HP pulls over 13 amps at 120v. The sticker says 6HP They got sued over this and I got a settlement from the class action.

As for your motor, upping the pressure won't hurt it a bit. The load on the motor is actually less at 135 PSI than it is at 100. This is because the compressor is not moving as much air. That sounds counter intuitive but if you put an amp meter on it you will see. I bet you have a 150 PSI popoff on the tank so I doubt you really have a safety problem.

[Roger Shoaf]

I do not think this can be true. If you increase the work, you will increase the load.

[Hustlin' Hank]

I agree Roger. Which also means an increase in heat at compressor AND motor AND current draw.

Hank

[trader4]

And I agree with you guys too. Anyone who's used a bicycle pump knows that while you are moving less volume of air at higher pressure, it takes a hell of a lot more work.

As to the original question, I wouldn't worry so much about the additional work load on the compressor from setting the kick in a little higher, especially since it's only used a few hours a year,

[Lp1331 1p1331]

FWIW, I have a Passlode Impulse nail gun-- actually have two, a framing gun and a trim gun, but haven't used the trim one yet. I love it, and would never go back to an air operated gun. Larry

[Stormin Mormon]

I wonder if there is a way to run the compressor continuous. And then let the relief valve do its thing when the pressure is too high. I would also think of adding a cooling fan.

[Stormin Mormon]

Refrigeration compressors, the amps go up with the head pressure. I doubt that anyone will find higher discharge pressure resulting in lower amperage. I may try it some day with my little pancake compressor.

[clare]

Good advice, but the nail gun doesn't use much VOLUME of air. It DOES require good pressure. Stting the cut-in pressure higher solves that problem, but makes it cycle oftener. Boosting the cut-out pressure reduces the cycling. The extra wear caused by the higher pressure will be partly offset by the reduction in stress from cycling, so over-all the life of both the pump and motor is unlikely to be affected a great deal by changing the settings. A larger tank will cause slightly longer (startup) run-times, but at the same CFM consumption the overall run time should not be affected.

[clare]

But ARE you increasing the "work"? If the flow drops off faster than the pressure rizes, the actual WORK is reduced. Not saying this happens on this compressor

[Bob F]

Or, a larger tank would let it cycle the same with a reduced high pressure.

[gfretwell]

Bingo, we have a winner. The amount of air moved drops off because the compressor loses efficiency at higher pressure. Air compressors are not HVAC compressors or bicycle pumps. It is just like putting your hand over a vacuum cleaner hose, the motor speeds up. If you really want to see this I will shoot some pictures of my compressor gauge at several pressures with the clamp on ammeter in the shot. I was surprised too, until someone explained it to me. The highest current is drawn at around 90-100 PSI on a compressor that shuts off around 150. It is a bell curve.

[Hustlin' Hank]

But the compressor/vacuum/outboard boat motor isn't working or producing anything or as much as it should. Therefore being less efficient. Another analogy is the outboard boat motor or centrifical pump. Cavitation will cause the motors to increase in RPM but the pump isn't pumping any liquid and the boat motor isn't pushing the boat.

Basically, If the amps are decreasing, less work is getting done. Less work will equal less heat, but heat will still build as the result of friction.

Hank

[Bob F]

Do it. I'd love to see the result.