service manifolds

[martinw58]

has anyone had there gauges calibrated was asked by insurance man if i had calibration certificate for my gauges

[Brian_UK]

I was led to believe that manifold gauges are self calibrating as you can adjust the zero before taking readings.

They are not test gauges merely indicators.

[Rob White]

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I think they can be classed as two types Brian.

Normal service gauges that we calibrate before use and even maintain / repair
ourselves and then the gauges that are used for pressure testing.

Our own gauges do not really need to be calibrated above being zeroed but
Pressure testing gauges if used for official commissioning and documenting do
need to be calibrated to prove they are within tolerance.
The same with our weighing scales as well.

Rob

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[Brian_UK]

I certainly agree with you there Rob as pressure tests are a certifiable event.

[RANGER1]

Probably depends on what you work on to a certain degree, but if not accurate what's the point!
We would calibrate our gauges & thermometers as a minimum annually against a calibrated, certified test gauge, log results, replace/repair as necessary.
Things get damaged, or out of calibration through general use.
If something goes wrong, or accident, you have some kind of traceability.

Pressure testing/vacuum.
Setting high pressure cut out switches, or verify transducer reading.
Back pressure regulators so don't freeze product, or set up as design.
Checking against gauges on site on compressor packages.
Verify performance of equipment.
Pressure drop in pipework
Superheat accuracy

Nothing worse than setting a heap of pressure switches when your pressure or temperature gauge is not reading correctly.
Digital can be wrong as well

Same with your vacuum pump, check vacuum etc