The Effects of Cryogenic Fuels on Capacitance Type Mass and Level Measurement

Various properties of cryogenic fuels such as ullage gas formation, radial and vertical density gradients, and boiling effects are outlined. The action of these properties on capacitance type mass and level measurement systems is discussed, including the action of ullage gas dielectric, effect of density gradient on probe placement, and the vapor barrier and bubble discontinuities introduced by the boiling effect. Compensation methods and optimum designs for some major cryogenic fluid effects are evaluated.

From this evaluation it is concluded that, although present readout systems offer accuracies in the 0.01% area, this accuracy cannot be realized without a complete system design which takes into account the effects of the cryogenic fluid on the system.