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Operating and maintenance instructions Section 2: Installation and set-up
3-9008-701 Rev J January 2015
Base volume certification 23
Figure 2-6 Connection diagram
2.3 Base volume certification
The prover base volume has been certified at the factory using the volumetric displacement
method (water draw) per API guidelines. The base volume has been adjusted to 0.0 gauge
pressure and the reference temperature as stated on the volumetric determination report
supplied with each prover documentation package. The operating computer will need to be
programmed with these base volumes. Upstream or downstream volumes will be used
depending on the application and location of the meter under test.
The volumetric displacement (water draw) technique, described in Section 4.2, is the factory
recommended procedure for certification of the base volume of the compact prover. It is
recommended that this procedure be repeated at regular intervals to confirm proper operation.
Frequency of base volume determination is dependent on usage, but should not exceed 3 years.
Certification may be necessary following repair or service procedures involving any disassembly
or seal replacement of the piston, poppet or flow tube. Certification is not necessary following
repair of the hydraulic cylinder if the flow tube is not disassembled. For specific information
regarding prover base volume certification related to maintenance of the optical assembly, see
Section 4.6. A lead seal wire should be installed to assure calibration integrity once certification
is completed as described in Section 2.5.
The upstream volume of any compact prover is slightly smaller than the downstream volume
due to the main piston shaft and optical shaft which are both located on the upstream side of
the piston.
If the meter is located upstream, or on the inlet side of the prover, then the upstream volume
must be used.
If the meter is located downstream, or on the outlet side of the prover, then the downstream
volume must be used.