Instrument Calibration

Now here is an accidentally very deep question.

The easiest, most precise but unfortunately most expensive answer is to hire the services of an internationally recognized calibration agency. In the United States this would be the National Institute of Standards. Your country would likely have a similar agency. Most likely you do not need this level of accuracy, precision and repeatability as this caliber of measurement can provide. This leads to the first question a good engineer should ask themselves of any measurement, "How accurate, precise and repeatable must these measurements be?" Only once this question is answered can one reasonably select if a Spackle bucket with felt pen markings for volume will be sufficient for part of your answer, if one must employ the skills of a research team, or at what point between these two extremes is "good enough".

A1-3) Why didn't the purchase orders embrace the manufacturer's calibration certificates. If they did, why have they been mislaid? No matter. They can be purchased retrospectively in response to the manufacturers receiving the serial numbers of the instruments.

A4) Valves cannot be calibrated. They can only be set up.

A5) Level indicators are not calibrated. They are set up by the Commissioning Engineer to suit the vessel, using the instrument manufacturer's set-up procedure contained in the instructions supplied with the instrument.

It sounds as though the organisation has acute documentation failures challenges as well as the lack of a viable instrument workshop.

1 Pressure source and a pressure reference and a good quality multimeter. Some test equipment has all three built in.(Need more details)

2 If the flow measurment is a D/P based flow measurment ( the most common ) then the equipment is much the same or very similar as point 1. ( need more details )

3 The temperature indicator can be checked with boiling water and or ice water this at least gives you two points to check. This is only valid if your TI's are to be used in this range of 0-250 deg F If the TI's are for 600 deg C then you will need some specific test equipment.( need more info )

4 & 5 NEEDS MUCH MORE INFORMATION