Selection of low-temperature valves

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I. Low-temperature materials: At temperatures below –180°C, plastic and elastic material components are no longer suitable. Within this temperature range, special consideration must be given to the packing and valve stem sealing elements; soft seals cannot be used anymore, as they become hard and lose their flexibility, failing to provide adequate sealing performance. Under these temperature conditions, special elastic materials must be used, and a specific load must be applied to achieve good cutting results. II. Issues to consider regarding packing seals: In low-temperature environments, moisture in the atmosphere will condense when the temperature drops below freezing point, forming a layer of frost. If frost forms on the surface of the valve stem, as the stem moves up and down driven by the actuator, this layer of frost may be pulled into the packing, causing tears and thereby compromising the seal. Therefore, an elongated upper valve cover should be used to keep the packing area of the control valve away from low-temperature areas, thereby preventing frost from forming in the valve stem and packing area. III. Typical low-temperature control valves: In low-temperature applications, the most suitable valve types are single-seat valves, double-seat valves, angle valves, and low-flow valves. Taking into account the requirements of low-temperature use in the design of these valves, and by equipping them with special extended upper valve covers, they can be turned into low-temperature valves. The length of the elongated upper valve cover depends on the temperature and insulation requirements of the application; the lower the temperature in the application, the longer the elongated upper valve cover.