SEALED THERMAL RELIEF VALVES REDUCE FLUID LEAKAGE AND SEAT LEAKAGE

Abstract

Rocket propulsion systems, long-distance transportation, and the long-term storage of vast quantities of frozen food all depend on cryoliquids. Cryoliquids are notoriously difficult to transport and store since they boil at a temperature below absolute zero. The expansion rates of these low-temperature liquids may reach 700 times, thus additional safety precautions must be included in the pipelines or storage facilities that house them. Pipes may rupture if internal pressure rises over safe thresholds. At this point, the significance of the safety pressure release valve becomes evident. When the thermal relief valve reaches a certain pressure, it will open to release pressure from the section and then shut to return to its starting position.

Most cryogenic systems have minimum air release capacity of 300 standard cubic feet per minute (SCFM) and thermal relief valves with metal to metal seating to prevent leakage. Surface finish limitations prevent metal-to-metal seated valves from achieving zero leakage or a Class VI leakage rating.

The feasibility of soft-sealing conventional metal-to-metal seated valves has been investigated. A soft seal is needed for the current disc and nozzle arrangement, and PCTFE (poly-chloro-tri-flouro-ethylene) may provide this. to use the valve's original spring. computations for strength and force balancing for the new disc shape. The leakage pressure was computed using the updated geometry. Next, we test it in the lab using air and liquid nitrogen. Longer term, more sensible and efficient It is being researched to create a cryogenic valve that can resist larger pressure surges.