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How do you guarantee the accuracy of your metering systems? Initial validation, and regular re-validation of all of the component parts of the metering system is the only way to achieve this. In some quarters there is a belief that metering systems are "fit and forget black boxes", this is most certainly not the case, and failure to properly check and validate all the elements of the metering system can, and will, expose the operator to a serious commercial risk.

What must be checked?

Primary elements, such as the orifice plates used in gas metering systems, must be inspected, cleaned, and regularly re-certified. On oil metering systems the prover volume will require regular re-certification. HMS can advise on the various methods available for this, and can arrange for the work to be carried out by an accredited organisation.

Secondary instrumentation such as DP (differential pressure), pressure, and temperature transmitters must be calibrated with certified test equipment to a high standard of accuracy, using the correct procedures. This even includes details like correcting deadweight testers to local conditions of ambient temperature and gravity. In many cases the DP  transmitters used on gas orifice metering systems need to be "footprinted". This is a transmitter calibration procedure that compensates for any calibration shifts due to high static pressures. HMS can advise on the requirement for this, and arrange for Footprint calibration to be done at a suitable accredited calibration facility.

Flow computer functions and calculations - such as totalisation - must be tested against independent off-line calculations to ensure they are correct.  In addition, the constants and system data - such as orifice plate sizes, and prover volumes - entered into the flow computer must be verified.  Incorrect data entry is a very  common source of error.

Analysers - such as gas chromatographs - must be checked and tested, and the validity of the data they produce confirmed. Densitometers are a vital part of most oil metering systems and special procedures are used to ensure the accuracy of this measurement.

All of this work requires specialist knowledge and experience in order for it to be carried out correctly. Although a competent instrumentation specialist will have the knowledge to carry out much of this work with some training, it's worth remembering that - as always with metering - a small error or omission, can over a relatively short period of time, cause VERY £ARGE ERROR$ in financial terms. Cutting corners does not pay.

HMS can undertake all of this validation work for you, or witness it being carried out by others and verify that it is done correctly.   In addition, we can also train your own technicians to carry out complete system re-certification to the required standard. See also: Training & Mentoring Services.