Pressure Measurements in Cryogenic Systems

Abstract

Pressure measurements In cryogenic systems have, for years, been made by simply running gauge lines from the point where the pressure measurement is desired to some convenient location at ambient temperature and attaching a suitable pressure-measuring device. This system works quite well for most applications ; however, there are disadvantages to this straightforward approach that may introduce problems in many systems. The two most important are (1) reduced frequency response and (2) thermal oscillations. In addition heat leak and fatigue failure of gauge lines could become significant In some applications. Such problems associated with pressure measurement at cryogenic temperatures could be eliminated by installing pressure transducers at the point of measurement; thereby doing away with gauge lines. Data gathered by the author Indicate that existing pressure transducers can be used at temperatures down to the liquid-hydrogen range, provided that the correct transducer for each application is selected, properly calibrated and installed, and Its limitations clearly understood.