Pressure Relieving/Holiday Valve (500X)


This valve is used for the high building fire fighting system. When the pressure in the water supply pipeline is over the one set for pressure relieving, the pressure relieving valve is opened to prevent both pipeline and equipment from getting damaged due to an excessive pressure; and, when the said pressure lowers to the set value, this valve will be closed automatically.


The body uses full-channel streamline design, leaving a small fluid resistance and a great flow. This valve can be used as a pressure relieving valve and also a pressure holding valve. When used as the former, it can relieve the pressure in the water pipe over the safety value set for the pilot valve and keep the pressure in the pipe below the safety value to prevent the system from getting danger due to an excessive water pressure; and, as the latter, it can keep the master valve upstream water supply pressure over a certain set value to make the water supply to the downstream only available when the upstream pressure Is higher than the set value so as to ensure the master valve upstream water supply pressure.


The inlet side of the master valve is connected to the pilot valve via a control pipe and, when the pressure at the said side is over the one set for the pilot valve, the pilot valve is opened to relieve the pressure in the upper cavity of the diaphragm and the main disc is opened along with. The master valve relieves pressure and, when the pressure lowers to the set one, the pilot valve is closed, so is the master valve.

Executive standard

  • Size of flange: GB/T 17241.6.
  • Test and inspection: GB/T 13927

Typical Diagram of Installation

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