Minimum flow valve: how to select the minimum flow valve?
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Release Time：2020-10-28
The minimum flow valve is usually installed on the branch pipe of the pump outlet. The minimum flow valve determines the caliber and pressure level of the minimum flow valve according to the minimum flow of the pump and the discharge pressure of the inlet and outlet. The minimum flow valve body is usually cast or forged steel. The minimum flow valve can be opened and closed by the following three methods: temperature, pressure and interlock with the outlet valve, and discharge a small amount of high-temperature water to prevent pump cavitation and ensure normal and continuous operation of the pump. In order to ensure a reasonable selection and ensure the service life of the pump and the minimum flow valve, it is best to let the engineer go to the site to confirm and then select the model.
The minimum flow valve is usually installed on the branch pipe of the pump outlet. The minimum flow valve determines the caliber and pressure level of the minimum flow valve according to the minimum flow of the pump and the discharge pressure of the inlet and outlet.
The minimum flow valve body is usually cast or forged steel. The minimum flow valve can be opened and closed by the following three methods: temperature, pressure and interlock with the outlet valve, and discharge a small amount of high-temperature water to prevent pump cavitation and ensure normal and continuous operation of the pump.
In order to ensure a reasonable selection and ensure the service life of the pump and the minimum flow valve, it is best to let the engineer go to the site to confirm and then select the model.
1. Definition of minimum flow valve:
The minimum flow valve is used in hot rolling descaling system of iron and steel enterprises. The medium is water, and the working temperature on the pipeline is ≤ 100 ℃; it mainly protects the normal operation of the water pump. The valve can only be fully opened or fully closed when in use.
2. The working principle of the minimum flow valve:
The minimum flow valve is usually installed on the branch pipe at the outlet of the water pump. When the pump is running normally, when the outer pipe supplies water, the minimum flow valve is closed. When the water pump is running normally and does not supply water, the water pump will not stop. The minimum flow valve is controlled by one of the three methods of temperature, pressure and interlocking with the outlet valve to control its opening and closing, and discharge a small amount of high temperature water. Prevent pump cavitation and ensure normal and continuous operation of the pump.
3. Minimum flow valve working mode
(1) The high-pressure descaling water (PN25MPa) of the rolling mill is controllable. The valve opens at 50°C and closes at 40°C.
(2) For ordinary water pumps, the outlet pressure of the pump is used for control. The pressure switch is installed on the main pipe of the pump outlet. When the pressure exceeds a certain set value (set by the designer according to the field), the minimum flow valve opens; when the pressure is lower than a certain set value, the minimum flow valve closes. In the case of external water supply and no external water supply, the pressure of the normal operation of the pump will fluctuate greatly. The design values for the opening and closing of the minimum flow valve can be set by the design institute personnel.
(3) Interlock the switch of the minimum flow valve with the main valve that supplies water to the outside and supplies water to the outside. The main valve is opened and the minimum flow valve is closed. Conversely, if there is no water supply, the main valve is closed and the flow valve is opened.
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2026/02/28
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