As recently as a few months ago, somebody who needed an internationally recognized calibration for a flow meter that operates with very low-temperature fluids such as liquefied natural gas had exactly one place on Earth to go: NIST's Cryogenic Flow Measurement Facility (CFMF) in Boulder, CO, which had been in continuous operation for 50 years.
"The CFMF has played a critical role for industry and manufacturing in the research and advancement of cryogenic flow metering for liquid nitrogen, liquefied natural gas, and other cryogenic metering applications," says Michael Lewis of NIST's Material Measurement Laboratory (MML), who managed the facility for years.
The venerable CFMF, however, was slated for closure. It was occupying space needed for construction of a building to house NIST's newest operating unit, the Communications Technology Laboratory. But NIST did not wish to abandon the stakeholders, most of whom are meter manufacturers.
What happened next is an illustrative example of private-public cooperation and technology transfer. In late September, 2015, scientists from NIST's MML and Physical Measurement Laboratory (PML) convened a workshop in which concerned parties from government and industry could discuss the future of the venerable facility and its unique capabilities.
The CFMF measures flow of liquid nitrogen, a suitable proxy for liquefied natural gas (LNG). LNG is typically handled and transferred at about -160 ˚C; nitrogen liquefies at -196 ˚C. The CFMF measures the liquid flowing through the meter under test at rates from 0.95 kg/s to 9.5 kg/s with a calibration uncertainty of less than 0.2% at 95% confidence level.
In the existing CFMF system, there are many aging parts and manual procedures in need of automation, and the facility requires oversight by an experienced flow metrologist. Very few organizations could easily take it over.
But one of the parties attending the workshop, the Colorado Engineering Experimental Station Inc. (CEESI), is in the business of calibrating flowmeters, though it doesn't manufacture them. Furthermore, CEESI already had a Cooperative Research and Development Agreement (CRADA) with NIST.
"CEESI said they could take the system apart and put it back together again in working order within three or four months," says Michael Moldover, Leader of PML's Fluid Metrology Group, a co-organizer of the workshop. "Not surprisingly, the flow-meter manufacturers were very interested in keeping the capability."
NIST modified its CRADA such that the facility will be loaned to and operated by CEESI for five years. In the last part of November, 2015, NIST disassembled the CFF and the parts were moved to CEESI's Nunn, CO, location. There NIST and CEESI will collaborate to update and automate the equipment, and to study the performance of meters for cryogenic liquids, particularly, Coriolis flowmeters.
Moldover says that "the improved CFMF located on CEESI's site allows NIST to continue delivering calibrations to its customers. Furthermore, the joint research will improve the understanding of the effects of temperature on calibrations. If the research is fully successful, the need for calibrating flowmeters at cryogenic temperatures will be eliminated."