Compressor Duty Cycle Question

[67cj5]

Huh? A piston type reciprocating compressors output and peak pressure is directly proportional to the mass (density) of air it can intake per stroke. Air density (and pressure) drops with altitude at a known rate. The air pressure gauge will be reading what is known as gauge pressure, this is not the same as absolute pressure. At an altitude of 0 feet the absolute pressure is approximately 14.7 psi. add 10,000 feet the absolute pressure is approximately 10 PSI. and thus the air compressor will be ingesting approximately 30% less air with each cycle.

That's silly because now you are talking about pressure related to Balistics, The Compressor will decide what it's Air pressure will be and they require very little Air Intake, To prove this I unscrewed the Air filter on the compressor and put my hand over the hole and I can't even feel it drawing the Air In so it would have little effect using them at altitude As Posted by Jadmt.

QUOTE:-

ditto. I have not used mine at really high altitude but have used it many times while at 8-10,000 feet with no issues including filling 8 35's. End Quote.

 

[luthj]

At high altitudes the work required to compress air from ambient pressure to tire pressure increases, the cooling available for the electric motor also decreases. The compressors peak output pressure will drop as well, but that is not as big of a deal given that the tires don't need high pressures.

I have used the MV50 myself, and it has proven quite durable. I have a viar 350 unit undermounted on my van. Mounting it uspide down caused the piston seal to fail early. The unit did a good job though, and I will rebuild with 50$ in parts.

 

[67cj5]

As posted by someone else it is safe to assume that of Altitudes up to 10K have little or now effect.

 

[luthj]

....To prove this I unscrewed the Air filter on the compressor and put my hand over the hole and I can't even feel it drawing the Air In so it would have little effect using them at altitude As Posted by Jadmt.

Please continue with your high informed description. Seriously, what do you think would happen to the compressors output at say 30k ft? It would still work just fine eh?

The reduction in compressor output with altitude is very real, and is a common issue for industrial and commercial compressor installs. For a user running a compressor at high altitudes regularly the de-rate of duty cycle or choosing a high flow compressor may be warranted.

 

[67cj5]

Please continue with your high informed description. Seriously, what do you think would happen to the compressors output at say 30k ft? It would still work just fine eh?

The reduction in compressor output with altitude is very real, and is a common issue for industrial and commercial compressor installs. For a user running a compressor at high altitudes regularly the de-rate of duty cycle or choosing a high flow compressor may be warranted.

Your just looking for an argument,, Out of a matter of interest how many roads are there up at 30K where even Helicopters don't fly ?

You talk of things that just don't exist because the tallest place on earth is only 29029 feet, So how are you going to get a compressor not to mention a Car above that, This I'd like to See, time to get some pop corn I think.

 

[IdaSHO]

At high altitudes the peak pressure a compressor can make will drop, as will its CFM. At 10kft the CFM will drop by 30%+ or so, peak pressure will drop a similar amount.

Correct on all counts, provided the compressor runs at the same RPM

Pretty simple really, less air per stroke = less CFM

And I'm pretty sure 67cj% is just arguing to argue at this point.

 

[IdaSHO]

And food for thought about higher altitudes and "work"

Pretty sure the compressor wont work harder, just longer.
Again, less volume per stroke.

 

[67cj5]

And food for thought about higher altitudes and "work"

Pretty sure the compressor wont work harder, just longer.
Again, less volume per stroke.

Unless your compressor is has Lungs and a Heart/Blood supply then it won't effect it, But you keep believing what you want, Someone Who Has done it has already told you it had no effect yet you still want to argue, Like I said try it at normal Altitudes and then go up 10K and Time it and take a pressure reading at both places then you will know for sure.

 

[67cj5]

Quote from Atlas Copco.

"The most important factor is the inlet pressure variations at altitude. A compressor with a pressure ratio of 8.0 at sea level will have a pressure ratio of 11.1 at an altitude of 3000 meters (pro-vided that the application's operating pressure is unchanged). End quote.

According to the tests I have seen, they require less power for some reason to achieve the same pressure.

 

[IdaSHO]

Sounds reasonable to me. Intaking less dense gas will take less energy to compress it.

Exactly what I was referring to with regards to nort working harder, just longer.

For a given volume of air, it would take compressor longer at high altitudes than low, to create the needed PSI difference you are using the compressor for in the first place.

 

[IdaSHO]

as I said...

https://www.vmacair.com/blog/compressor-system-perform-differently-higher-altitudes/

 

[IdaSHO]

Same volume per stroke. Its just that volume is less dense.

We are talking about air, so volume of air per stroke, yes

Same difference, for a given amount of work (PSI change), the compressor will simply be required to run longer

 

[67cj5]

Compressor testing never seems to match real world testing.

 

[roving1]

Again you are twisting what I am saying, My point was if a Gauge is unaffected by Altitude then compressor should not be effected eigher.

Dude, you are not really commenting on point with what anyone is saying. No one mentioned a guage.

At a minimum the thinner does not carry waste heat off of the compressor as well. My compressor also runs longer to do the same work at altitude despite theories posited here that it should make no difference. Try airing tires up at 10-13K. It's not an impossible to prove mystery.

 

[67cj5]

Dude, you are not really commenting on point with what anyone is saying. No one mentioned a guage.

At a minimum the thinner does not carry waste heat off of the compressor as well. My compressor also runs longer to do the same work at altitude despite theories posited here that it should make no difference. Try airing tires up at 10-13K. It's not an impossible to prove mystery.

It's not about Gauge's, My point about the Gauge was if it is unaffected then neither should anything else be, After all It is measuring what the compressor is putting out,

AGAIN, Someone has already posted that their compressor was unaffected at 10K, So I will take them for their word.

It matters less to me whether it does or does not because I have no intension of driving in such areas but if I did decide to go up that high my Gear is more than able to deal with such environments, With my compressors being over kill I would not notice the effects anyway.