DIYbanter - View Single Post - Is there any reason not to charge a compressor upto 8bar?

On 7 Feb 2006 09:02:32 -0800, wrote:

I have just got my new 100 Litre (3hp) upright compressor and notice
that its only charging to 7bar.

I wondered if the gauge was inaccurate, but its got 2 and both read
almost exactly the same.. As I final test, I have a engine compression
tester which I connect and indeed its at around 7 bar.

Is there any reason why I should not adjust the 'cut off' so that it
fills to 8bar? If it has 8 bar in the tank as opposed to 7, then I
assume am going to get more air out (100 litres more), but its
obviously going to take longer to charge and will put extra pressure on
the tank and fittings.

Has it been set to 7 intentionally, or is it normal to 'fine tune' it
during its first few used?

If this is a single-stage one cylinder compressor, 7 BAR / ~100 PSI
is a reasonable setting and will run most any tool you have. You can
go slightly higher IF the pump and motor combination can handle the
extra load, and the tank and plumbing are rated for it.

The manufacturer deliberately sets the pressure switch in the
factory at a "safe" level slightly lower than the maximum the pump and
motor assembly can attain, so they don't have to deal with failures
brought on by excessive running time (as it labors to get that last
pound) or motors overheating.

All pumps have a maximum pressure where you don't get any useful
output, and for a small single stage, that's about it. If the motor
doesn't overload and stall, the pump output drops off to nothing.

And they set the switch with a reasonable differential point of
between 15 - 30 PSI (1 - 2 BAR) so it isn't starting and stopping
constantly - you can damage the motor by starting it more than 6 to 10
times an hour, the start capacitor or winding can overheat.

If you need higher pressures on a regular basis, you have to go to a
two-stage pump. They are good for 150 - 175 PSI.

-- Bruce --
--
Bruce L. Bergman, Woodland Hills (Los Angeles) CA - Desktop
Electrician for Westend Electric - CA726700
5737 Kanan Rd. #359, Agoura CA 91301 (818) 889-9545
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