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Equipment Tests > 12-Volt Air Compressor Comparison
12-Volt Air Compressor Comparison
Officially, Duty Cycle should be measured with the compressor pumping at 100psi at an ambient temperature of 22 degrees Celsius. The duty cycle is expressed in a percentage and is calculated by run time divided by the addition of the run time plus the off time, then multiplied by 100.
As an example: if a compressor is rated at a 25 percent duty cycle, it can only (theoretically) run for 10-minutes followed by 30-minutes turned off.
So, 10 / (10 + 30) multiplied by 100 = 25 percent duty cycle...not 33 percent as most would presume (10/30 multiplied by 100 = 33 percent).
Here are a few ratings so you don't have to hit the calculator, but do keep in mind that these technical figures are at 100psi and 22 degrees Celsius. Pumping at less pressure and varying temperatures will change the whole show:
An internal thermal cut out switch is primarily designed to protect the air compressor's motor from burning out or over heating. You'll have no control over this thermal cut off; when the unit heats to a preset temperature, it (theoretically at least) stops, leaving you twiddling your thumbs waiting for it to switch itself back on.
Price - that's the tough one. We all want to spend as little as possible, but want the best out of our gear. We've managed to round up most compressors on the market that are (or are claimed to be) suitable for 4WD tyre inflation, as well as general use around the camp site. We've drawn a line at the units being portable; that is, they must be able to be carried and used from one vehicle to another - not engine mounted or engine driven. Of course, most of the compressors you see here can indeed be mounted in your engine bay, under your seats or in your cargo area, but they are all initially portable units.
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TESTING TIMES
As we were keen to test all the air compressors both scientifically and in real life situations, we figured on hooking up with ARB's state of the art Air Compressor Dyno and their design engineers Daniel Bongard and Sam Steward to measure all the technical issues of each and every compressor - maximum achievable pump pressures, motor temperatures, currant draw, air flow rates (standardised to 20?C at sea level) and whether or not the thermal cut offs worked. We ensured a constant 13.8-volts to simulate a vehicle's electrical system with the engine running.
To capture all these results, the test equipment automatically captures data while the compressors are pumping into a pressure vessel to a maximum of 130psi. The internal and external temperatures of the vessel are known, the time, current and every piece of data is recorded to ensure accuracy. Graphs are automatically derived from the captured results to provide a real overall picture of how each compressor operates at any given pressure. All you need to do is run your finger along the bottom of the graph to reach the pressure you're operating at and you'll see the currant draw and flow rates in litres per minute - brilliant!
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As an example: if a compressor is rated at a 25 percent duty cycle, it can only (theoretically) run for 10-minutes followed by 30-minutes turned off.
So, 10 / (10 + 30) multiplied by 100 = 25 percent duty cycle...not 33 percent as most would presume (10/30 multiplied by 100 = 33 percent).
Here are a few ratings so you don't have to hit the calculator, but do keep in mind that these technical figures are at 100psi and 22 degrees Celsius. Pumping at less pressure and varying temperatures will change the whole show:
An internal thermal cut out switch is primarily designed to protect the air compressor's motor from burning out or over heating. You'll have no control over this thermal cut off; when the unit heats to a preset temperature, it (theoretically at least) stops, leaving you twiddling your thumbs waiting for it to switch itself back on.
Price - that's the tough one. We all want to spend as little as possible, but want the best out of our gear. We've managed to round up most compressors on the market that are (or are claimed to be) suitable for 4WD tyre inflation, as well as general use around the camp site. We've drawn a line at the units being portable; that is, they must be able to be carried and used from one vehicle to another - not engine mounted or engine driven. Of course, most of the compressors you see here can indeed be mounted in your engine bay, under your seats or in your cargo area, but they are all initially portable units.
read on below advertisement
TESTING TIMES
As we were keen to test all the air compressors both scientifically and in real life situations, we figured on hooking up with ARB's state of the art Air Compressor Dyno and their design engineers Daniel Bongard and Sam Steward to measure all the technical issues of each and every compressor - maximum achievable pump pressures, motor temperatures, currant draw, air flow rates (standardised to 20?C at sea level) and whether or not the thermal cut offs worked. We ensured a constant 13.8-volts to simulate a vehicle's electrical system with the engine running.
To capture all these results, the test equipment automatically captures data while the compressors are pumping into a pressure vessel to a maximum of 130psi. The internal and external temperatures of the vessel are known, the time, current and every piece of data is recorded to ensure accuracy. Graphs are automatically derived from the captured results to provide a real overall picture of how each compressor operates at any given pressure. All you need to do is run your finger along the bottom of the graph to reach the pressure you're operating at and you'll see the currant draw and flow rates in litres per minute - brilliant!
next page »
