Design Of Liquid-level Test Standard Device

Level Gauges are commonly used in liquid-level test based onprocess control. In recent years, level instrument began to be used in thefield of tank liquid-level measurement for the reason of the continuousimprovement of the level instrument precision and tank levelmeasurement requirements. Level Gauge is not a legal measuringinstruments, measurement accuracy has not been widely recognized andthe objection would not be able to judge.International recommendations R85(Level instrument formeasuring the storage tanks) is released by international metrologyorganization (OIML) in2008. This indicates that the liquid-levelinstrument used in the field of Tank Gauge is recognized byInternational metrology organizations and can be used as measuringinstruments for commercial handover. For the reason that liquid-leveltesting standard equipment for type evaluation has not yet beenestablished, the level gauge used as measuring instruments is to bedeveloped.To face this situation, this subject was first proposed the idea of aliquid-level test standard device establishment based on the laserinterferometer principle, and several works have been mainly done:(1)Overall designs for liquid-level standard device establishmentare given:①The idea of establishing a liquid-level test standard devicebased on laser interferometer principle is proposed, and the overalldesign of liquid-level test device is given.②Control program ofliquid-level lifting system is proposed.③Design of both oil-and-gasrecovery process and water biochemical treatment process are proposed.(2)Inside and outside double float structure, which can be appliedto liquid-level measurement based on the laser interferometer principle,is developed. And the measurement stability of the liquid-level testdevice is solved.(3)Measured values compensation for air in liquid-level teststandard device based on Edlen formula is proposed, and Edlen formulatransformation has been completed in order to meet engineeringapplications.(4)The stability test of liquid-level standard test device indicatesthat the stability meets the design requirements. The calibration test forliquid-level test device certificates that the test calibration device meetshigh-precision zero-calibration requirements, and design basis isprovided by the design of automatic calibration device. Functionrelationship among the output value, temperature T and pressure P in oiland gas measurement is obtained by oil and gas optical path test.The overall design of the liquid-level test standard device proposedin subject has been proved to meet design requirements by partial keytests, more verification debugging is to be finished in late works.