Summary of the settings of pressure relief valve, emergency shut-off valve and emergency opening valve: These types of valves have been developed and widely used in recent years, especially in the construction and fire protection industries. This article provides an overview and personal insights into their functions and applications.
Keywords: pressure relief valve, emergency shut-off valve, emergency opening valve, hydraulic control valve, fire protection
1. Pressure Relief Valve
A pressure relief valve is typically installed on the outlet pipe of a fire pump and remains closed under normal conditions. When the pressure in the fire water supply system exceeds a pre-set value, the valve automatically opens to prevent damage caused by overpressure.
Overpressure in the fire water supply network can occur for several reasons. For example, if the pump's flow rate is selected based on the design flow rate, but its head curve is steep, overpressure may happen during low-flow operations such as self-tests or early-stage fires. Additionally, when the pump stops due to power outages or other issues, water hammer effects in the outlet pipe can also cause overpressure if no proper measures are taken.
When installing a pressure relief valve, it's important to consider its location, size, pressure setting, and necessary accessories.
According to the draft revision of the Design Code for Automatic Sprinkler Systems (GB50084-2017), Article 10.3.3 states that "each group of pumps should be equipped with a control valve on the outlet pipe... and if necessary, a pressure relief valve should be provided." The final version was adjusted to say, “...measures should be taken to control the outlet pressure of the water supply pump.†This includes the use of a pressure relief valve.
When installed on the fire pump’s outlet pipe, the pressure relief valve can be placed either before or after the check valve. Installing it before the check valve helps eliminate overpressure caused by low-flow operation, while placing it after the check valve (in the direction of water flow) not only manages low-flow overpressure but also prevents overpressure from water hammer when the pump stops. Even without additional water hammer suppression measures like a speed-closing or slow-closing check valve, buffer tank, or similar devices, the pressure relief valve ensures safety and avoids damage.
2. There are two common installation methods for pressure relief valves: one is using the same diameter as the main fire water supply pipe, and the other involves using a DN100 or DN150 valve.
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