The ZHJPD pneumatic diaphragm cryogenic control valve is a precision automated execution unit specifically engineered for cryogenic services such as liquid nitrogen, liquid oxygen, liquid argon, and LNG. This valve consists of a multi-spring pneumatic diaphragm actuator and a single-seated valve body integrated with an extended long-neck bonnet. The core design features the extended bonnet to keep the packing box away from the cryogenic media, preventing the packing from freezing or losing elasticity, thereby ensuring reliable stem sealing. By receiving standard 4-20mA signals from control systems, the actuator converts air pressure into linear displacement via a positioner to achieve accurate proportional regulation of flow, pressure, and temperature. The ZHJPD series is characterized by its compact structure, sensitive response, impact resistance at low temperatures, and superior sealing, widely used in air separation units, gas liquefaction, and cryogenic scientific experiments.

Product Image of ZHJPD Pneumatic Diaphragm Cryogenic Control Valve

Feature

1. Extended long-neck bonnet protection:Utilizes an extended bonnet to increase heat exchange surface area, maintaining the packing temperature above 0℃ to prevent ice damage and stem seizure.
2.Cryogenic material system:Body and internals are made of austenitic stainless steel (e.g., 304, 316L) and undergo cryogenic treatment (liquid nitrogen soaking) before finishing to eliminate residual stress and ensure dimensional stability.
3.Tight shut-off performance:The single-seated design combined with precision-ground surfaces maintains high sealing integrity under cryogenic conditions, meeting Class IV or VI (bubble-tight) standards.
4.High-precision pneumatic actuator:Equipped with a compact multi-spring actuator for stable thrust and high positioning accuracy. Paired with a smart positioner, it achieves minimal dead zones and excellent linearity.
5.Intrinsically safe attributes:Driven by compressed air, it eliminates spark risks, providing natural explosion protection suitable for flammable and explosive cryogenic gas environments.
6.Optimized low-flow resistance path:The S-streamlined internal cavity ensures a small resistance coefficient and high flow capacity, significantly reducing pressure drop and cooling loss.
7.Precision top-guided system:Large-area top-guiding ensures precise axial alignment of the plug throughout its stroke, effectively resisting mechanical vibration caused by fluid impact.
8.Ease of maintenance and long life:The refined design allows for straightforward replacement of packing and internals. Key components meet cryogenic design codes, ensuring a long service life.