Basic information
This sustaining valve is opened to prevent the pipeline and equipment from being damaged due to overpressure when the pressure in the water supply pipeline exceeds the set pressure of pressure relief. The valve closes automatically when pressure drops to the set value. 
Features
1. Accurate Pressure Control
2. Fast Opening to Maintain Line Pressure
3. Slow Closing to Prevents Surges
4. Completely Automatic Operation
Principle
Inlet pressure water enters the lower cavity of the pilot valve diaphragm from the guide valve when the pressure in the pipeline exceeds the set pressure of the guide valve to make its pressure increase to open the guide valve, the main valve control room outwards drain under the effect of the inlet pressure water to open the main valve, it starts to discharge pressure. When the pressure in the pipeline drops to the set pressure, the pressure in the lower cavity of the guide valve diaphragm decreases, causing the guide valve closed. This results in increased water pressure from the guide pipe to the pilot valve, then to the main valve control room. The main valve plate closes and begins to hold pressure. 
Installation and Commissioning
The pressure relief(sustaining) valve supports horizontal and vertical installation but should pay attention to the inlet and outlet direction of valve body water when installing. In general, one fire water supply system can only install one pressure relief valve. Within the operating pressure range of the spring specified in the nameplate, the opening pressure can be adjusted by rotating the adjusting screw to change the spring compression amount. For specific use, please consult ZECO Valve Group.
Product Scope, Standards & Materials
Size Range: 2"~24"
Pressure Rating: 10bar ~ 25bar
Face to Face Dimensions: AMSE B16.10, EN558-1
Flange End Dimension: AMSE B16.1/16.42, AS4087, EN1092-2
Coating: Fusion Bonded Epoxy Coating
Inspection and Test: ISO 5208 / EN 12226-2

Zheng feng is one of the most professional water gate valve manufacturers and we have been devoted to produce China control valve for many years. If you want to know more details or want a quotation, just feel free to contact us!