CRYOGENIC TRANSFER STANDARD FOR FIELD CALIBRATIONS OF BULK TRANPORT SYSTEMS
The dream of a quick, simple, and reliable field calibration system for cryogenic flowmetering systems has become a reality with the introduction of the Hoffer SY-14B Cryogenic Transfer Standard. When suitably documented by a NIST traceable laboratory, the system offers users a high accuracy standard of comparison to allow adjustment of bulk transport mounted systems. Maintaining accuracy to the requirements of Handbook 44/OIML was never so easy.
Historically, the accuracy of flowmetering systems for bulk transports has been verified by comparing the metered delivery with the net weight delivered on a certified truck scale. To eliminate road loss errors, the bulk transport had to pump, while on a weigh scale, into a second empty transport off the weigh scale. The low precision resulting from scale inaccuracy and resolution necessitated very large sample sizes and lack of control in pumping rates. In addition, the weight measurements could not be made while pumping. This resulted in atime-consuming process where the pump was started and stopped repeatedly and which tied up the two trailers and the weigh scale for typically four hours per calibration check. In addition, when finished, both trailers had to be filled before going to their next delivery. With the Hoffer SY-14B Cryogenic Transfer Standard these problems are eliminated. First, only the trailer to be tested need be present in most cases. The discharge from the trailer is pumped from the transport to the SY-14B and back through the top fill connection to the trailer.
The system includes a transfer standard turbine flowmeter and a metering run mounted on a hand truck and an electronics console for portability. The electronic portion of the prover is provided in a small portable electronics enclosure with military style quick disconnect electrical fittings. Instantaneous indication of the flowrate and flowing temperature is provided as well as a total flow indicator, and an accumulative test total indicator. Temperature compensation for LIN, LOX and LAR, and other product types are provided to allow the total display to be in mass or volumetric units.