Compressor Duty Cycle Question

[IdaSHO]

Most have internal MOTOR protection that is commonly a thermal protection.
And since pretty much every MFG uses the same chinese motors, they are pretty much all set to 105C Thats 220+ degrees F.

And remember, that's MOTOR temp, cylinder temp when the motor is at 200 degress is most likely an additional 50 degrees, all on a compressor that uses O-ring pistons.

If you really want the compressor to last, the motor is not the concern, what you need to worry about is cylinder head temp.

That is, unless you run an MV50, and dont care if you have to replace it.... if it ever actually melts down

 

[jadmt]

here is what I can tell you. I have a viair 400P and I have pumped 8 35" tires up from around 10psi to around 30psi without giving the pump a break and it has never kicked off. make sure when you use your pump you keep your engine running and connect directly to the battery. I initially was worried about the 33% duty cycle but it is no longer even a thought with me.

 

[67cj5]

here is what I can tell you. I have a viair 400P and I have pumped 8 35" tires up from around 10psi to around 30psi without giving the pump a break and it has never kicked off. make sure when you use your pump you keep your engine running and connect directly to the battery. I initially was worried about the 33% duty cycle but it is no longer even a thought with me.

Yeah the 400 is a really nice piece of kit,

 

[Mighty Dodge Ram]

Same experience with the 400P, but I use it to pump up 4 LT tires to highway pressure...from ~ 25# to 60#. No problema. I bought it for the CFM rating, not the PSI rating regardless of the duty cycle.

 

[roving1]

here is what I can tell you. I have a viair 400P and I have pumped 8 35" tires up from around 10psi to around 30psi without giving the pump a break and it has never kicked off. make sure when you use your pump you keep your engine running and connect directly to the battery. I initially was worried about the 33% duty cycle but it is no longer even a thought with me.

This is what I have. Never done 8 tires but I have done 4 a bunch at really high altitude which I think might be just as hard in the compressor

For the others all I was implying is that the duty cycle rating at a 100psi is not a useful rating for what something will do at 30psi. The standard has its purpose I am sure and is not difficult to understand but if you are not running air tools or filling commercial tires it's not the whole story. Thats all I was saying. I don't know why that triggered so many long posts. I never claimed the cycle would double at lower pressures or that waiting a bit to fill tires was a problem.

 

[67cj5]

This is what I have. Never done 8 tires but I have done 4 a bunch at really high altitude which I think might be just as hard in the compressor

For the others all I was implying is that the duty cycle rating at a 100psi is not a useful rating for what something will do at 30psi. The standard has its purpose I am sure and is not difficult to understand but if you are not running air tools or filling commercial tires it's not the whole story. Thats all I was saying. I don't know why that triggered so many long posts. I never claimed the cycle would double at lower pressures or that waiting a bit to fill tires was a problem.

It does not matter what you was implying, no one is accusing you of anything, we are just sharing knowledge gained over the years, it's no reflection on you. And I should imagine it would take a very high altitude before it has an effect on a compressor.

 

[jadmt]

It does not matter what you was implying, no one is accusing you of anything, we are just sharing knowledge gained over the years, it's no reflection on you. And I should imagine it would take a very high altitude before it has an effect on a compressor.

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.

 

[67cj5]

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.

Funny you should say that because ARB quote in all their Gauge info that Altitude has no effect on their Gauges and seeing as some of their gauges are/get connected to compressors I should imagine the results would be the same as what you found ? Thanks for that.

Quote from ARB:-
the quality bronze Bourdon Tube gauge design ensures accuracy is not affected by fluctuations in temperature, humidity or altitude. Unquote.

 

[IdaSHO]

Uh, I don't think he mentioned anything about the gauge, or gauge accuracy.

Altitude should have little to no effect on any part of the compressor (within reason.... you do need air! )

And running the engine while airing up is always advised, as keeping the voltage up reduces the amperes the compressor motor will pull, all the more better for the motor itself.

 

[67cj5]

Uh, I don't think he mentioned anything about the gauge, or gauge accuracy.

Altitude should have little to no effect on any part of the compressor (within reason.... you do need air! )

And running the engine while airing up is always advised, as keeping the voltage up reduces the amperes the compressor motor will pull, all the more better for the motor itself.

The topic of Altitude and Gauges was not about accuracy, The point was if the Gauges are not effected then neither the compressor would be, Another thing Cars run ok at those altitudes although much High they have to be tuned to suit because they use a blend of fuel and Air but a Compressor sucks in the Air it is not dependent on Oxygen levels like We are or Vehicles are, Regardless of what it is whether is it If a compressor can draw it in it will pump it out at volume. and although the outside pressure changes the pressure within the system is made by the compressor and should remain stable because it is a closed circuit as is the Tyre.

 

[IdaSHO]

The topic of Altitude and Gauges was not about accuracy,

Yeah, that was exactly my point. YOU brought it up...

 

[luthj]

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.

 

[67cj5]

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.

That's not right because Astronauts would not be able to breath in outer space,

The whole topic is just speculation unless you go to sea level and run a test there and then go up 10-12k feet and log the run time of the compressor and both levels. until someone does that it is just guess work.

 

[67cj5]

Yeah, that was exactly my point. YOU brought it up...

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.

 

[luthj]

That's not right because Astronauts would not be able to breath in outer space,

The whole topic is just speculation unless you go to sea level and run a test there and then go up 10-12k feet and log the run time of the compressor and both levels. until someone does that it is just guess work.

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.