Dosing system for cryogenic fluids - has piezoelectric dosing tap whose dia. is varied by applied voltage and gravity feed

摘要

The cryogenic fluid is held in an insulated vessel (1), open to the top for pressure equalisation. The tap is operated by the piezo-electric element (9, 8) to vary the rate of outflow. No mechanical moving parts are required. The reservoir has a constant level top-up if long periods of dosage are required. The dosing is via current pulses or via a set current level applied to the pole pieces. A simple adjustable power supply drives the tap. ADVANTAGE - Precision dosing control, minimum risk of tap freezing.