SPSE flowmeter proving – bi-directional calibrations

SPSE owns and operates a centralized flowmeter proving facility. This accredited flow laboratory is used for SPSE’s own needs and by third parties (mainly manufacturers). The following text describes how the specific requirements of a flowmeter manufacturer were met in the facility.

Proving Facility

The facility allows calibrations up to 4000m3/h within a range of viscosities from 0.5 to 150cSt on standard (accredited up to 500cSt).

The proving station is COFRAC accredited. This means that the process is mastered and the uncertainties guaranteed. It gives the calibration results a multilateral recognition from other countries certification services.

Bidirectional calibration
Our client wished to calibrate bi-directional coriolis meters. As a special requirement, he wished the meters to be calibrated in both flow directions without disassembling between testing.

On standard calibration, a bidirectional flowmeter is first calibrated in one flow direction. Then it is disassembled to be turned around and calibrated in the other flow direction. The fluid always goes in the same direction.

For this requirement, it was decided to use the two parallel calibration lines as a valve system allowing the flow direction to be changed in a custom built third line.

The calibration was made with 4 different fluids with a viscosity range from 1cSt up to 100cSt. The results were good in both directions. A master meter was connected in series with the meter to be tested. The master meter was turned around when necessary. The results showed that the intermediary disassembling/assembling didn't have any significant consequences on calibration results.

Therefore, the bidirectional line is only interesting for assembly cost reduction. From a metrology point of view the classical calibration method gives the same overall performance.