3.2.3 Small volume or compact type

A small volume or compact type of prover uses a displacer which travels through a very short section of the pipe or cylinder (see Figures A.4 and A.5 ). The volume displaced in the calibrated section is usually much smaller than that of a conventional prover (such as in 3.2.1 and 3.2.2 ). For this reason, highprecision detectors and a method for pulse-interpolation are necessary to achieve good repeatability and high accuracy.