An Overview
Small Volume Provers:

There are many advantages to the small volume prover which make it a most desirable proving standard, says Steve Baldwin.

Introduction
Liquid meter proving is carried out by placing a Meter Prover in series with the meter under test; the prover having a calibrated base volume. Proving of the meter is accomplished by comparing the quantity recorded by the meter with the calibrated quantity displaced by the prover. It is a well-accepted practice that any primary custody-measuring dynamic device must be verified with a standard which has superior performance. This verification is done in-situ, in field irrespective of the flow meter being a PD, Turbine, Co- riolis or Ultrasonic type. Typically, this comparison is accomplished by proving the flow meter using a conventional ball prover or a small volume prover calibrated in accordance with API MPMS Chapter 4. Among all the methods, the master meter technique (Volume master meter is proved “in-situ” by a direct method i.e. either by a ball prover, small volume prover or tank type prover) is a lower precision technique. The objective in custody transfer, is to obtain the optimum measurement accuracy, regardless of the volume handled. The measurement accuracy accuracy of a custody transfer system depends upon a multitude of factors due to possibilities and options of the flow meters, prover, proving philosophy, valving, control, metering run installation, control of fluid parameters during proving and any other equipment selected for that measurement system. A system providing accurate data, low maintenance, minimal product contamination and being versatile as an “application fit” is preferred.


Pipe Prover: Conventional and Small Volume Prover
Conventional pipe prover also known as the ball prover has been used in the oil industry for many years. As a consequence, their capabilities and limitations are well understood and numerous standards are available. For example, the low lubricity of LPG poses special problems. They limit rangeability due to lunging or jumping of the sphere at low velocities. Varying design changes have been adopted in the field with special graphite impregnated internal coatings and/or graphite impregnated sphere. Over the past twenty years, the small volume prover has been developed and is very successfully used as an alternative to the conventional ball prover.

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