Water hammer check valve features

The actual problems in the development of water hammer centralized heating in the hot water heating system occur. The influence of the check valve type on the water hammer pressure of the heating system has increasingly attracted the attention of the domestic and foreign heating industries.

In the hot water heating system, waterproof hammer check valves should be used as much as possible. The waterproof hammer check valve overcomes the shortcomings of common check valves and has the following features:

(1) The valve can be opened promptly after the pump is started.

(2) In normal operation, it is required that the valve flap have the largest possible opening angle and be stable in the fully open position.

(3) When the pump is stopped, the valve has an optimized shut-off feature. When the pump is stopped suddenly, it can prevent the water backflow protection pump from causing a flyover and reversal, thereby achieving the purpose of protecting the water pump and enabling it to slow down in the final stage of closing. , To reduce the sudden shutdown of water hammer in the pipeline to achieve the purpose of protecting the pipeline.

Install a common check valve at the outlet of the pump; when the pump is stopped, the measured curve of the pressure on the downstream side of the check valve changes over time (Fig. 2(a)); and install the Danish Danfoss 402M waterproof hammer check valve at the pump outlet. The measured curve of the pressure on the downstream side of the check valve over time when the pump is stopped (Figure 2(b)). The diameter of the test tube is 150 mm, the flow rate in the steady state is 155 m3/h; the pressure on the downstream side of the check valve is 5 bar. As can be seen from Figure 2, when the ordinary check valve is installed, the maximum pressure at the check valve caused by the stoppage of the pump is up to 20 bar, while the maximum pressure at the check valve is only 10 bar under the same working conditions when installing the water hammer check valve. , reducing the water hammer caused by stopping the pump.