Using air compressor to calibrate sensor

Old 03-02-16, 08:37 AM
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Using air compressor to calibrate sensor

Hello, right now i am calibrating a pressuresensor and im using this aircompressor for the calibration:
6-4 - JUN-AIR

The measure span is from 0-7 psi, and the accuracy has to be +-0.15 psi.

But the questions is, how accurate is the pressure gauge on this aircompressor?
I tried to search on the internet, but i couldn't find the accuracy any places.

This is the pressure gauge:
5130000 - Pressure Gauge (0-16 bar) - Gast Manufacturing
Old 03-02-16, 08:55 AM
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The gauge that comes with any compressor is technically not calibrated and can not be relied on to calibrate other gauges. And, you want to measure 0-7 psi within +- .15 psi but then link to a gauge that goes to 230psi which is also not calibrated???
Old 03-02-16, 08:58 AM
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At best it will be +/- 1 % of full scale, and probably worse since it's basically a spring gauge. And with a full scale of 230 PSI, you can barely make out where 7 PSI is on the gauge.

No where near accurate or precise enough for what you are trying to do. I'm a afraid you will need a much more expensive instrument to achieve your precision and accuracy.
Old 03-03-16, 03:06 AM
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The style of gauge you linked to is nowhere what you need for the accuracy you said you want.
A digital gauge would be needed.

What exactly is the sensor you are trying to calibrate measuring and does the gauge need to be certified.
If what you are calibrating is a critical component for something you would do well to have a gauge with NIST certification for accuracy.
We don't know if you are working with an engine sensor or a medical device or a missile.

Not sure if certification is avaiable for this gauge but is the type you need.
Old 03-03-16, 08:55 AM
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At 7psi an accuracy tolerance of .15 is 2% of span so it's critical you get a gauge with a full scale in that range in order to maintain accuracy. Damaging such a sensitive gauge with a 120psi compressor is a very real possibility. It would be preferable to use a small hand pump like a basketball inflator or a Mity Vac if you could plumb it to a regulator that's capable of maintaining pressure that low.

A 230psi gauge has no reliable accuracy down at 7psi.
Old 03-03-16, 11:18 AM
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There is a bit of a difference between gauge accuracy range when comparing digital to analog

Within reason a digital gauge has an accuracy that remains constant through out its range.
If you are looking to calibrate at 7 psi you would not want to do it on a 10,000 psi gauge but a 300 psi gauge should not be a problem.
Depending on how sensitive the object of your calibration is a gauge that has a NIST certification is guaranteed to read correctly and if you do not need that certification to purchase the same gauge without the certificate is often 1/3 cheaper.
I use a NIST certified digital gauge that has a range of 0 - 150 psi and calibrate a medical device at 3 - 20 psi.

If we knew what is being calibrated we may be able to help more.

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