The Prevention Measures of Water Hammers
There are many prevention measures for water hammers. Different measures will should be taken according to the possible causes of water hammers.
1. Reducing the flow velocity of the water pipeline
Reducing the flow velocity of the water pipeline can lower the pressure of the water hammer to a certain extent, but this will result in increasing the diameter of the pipe and the investment of the pipe project. Avoiding sudden changes of slopes should be taken into account when water pipelines are installed. The water hammer of a stopped pump is mainly related to the geometric pumping head of the pump house. The higher the geometric pumping head is, the greater the water hammer value of the stopped pump becomes. Therefore, reasonable pumping heads should be selected according to the real local condition. When the pump is stopped due to an accident, the check valve and the pipe should be filled with water before starting the pump. When the pump is started, the valve at the outlet of the water pump should not be fully opened. Otherwise, great water hammers will happen. Many accidents caused by water hammers often occur in pump stations under this circumstance.
2. Setting the water hammer elimination device
(1) Using the constant pressure control technology
Low pressure or overpressure often occurs in the operational process of the pipeline system, because the pressure of the water supply pipeline changes with the working conditions, which will easily cause the water hammer, resulting in damage to the pipe and the equipment. Adopt the automatic control system to control the water pump’s opening, closing and speed by the test and feedback of pipeline’s pressure; control the flow rate to make the pressure maintain a certain level; set pressure of the pump’s supply water to maintain constant pressure water supply by controlling the microcomputer and avoid great pressure fluctuation to make probability of the water hammer smaller.
(2) Installing the water hammer eliminator
The water hammer eliminator is adopted for preventing the water hammer of a stopped pump, and it is usually installed near the outlet pipeline of the water pump. The water hammer eliminator uses pressure coming from pipes as power to obtain automatic operation of low pressure. That is, when the pressure of the pipe is lower than the set protection value, the water outlet will be opened automatically to release water and pressure, which will balance the pressure of the partial pipeline and prevent the damage to the equipment and pipe caused by the water hammer. Generally, the eliminator can be divided into two types, the mechanical eliminator and the hydraulic eliminator. The mechanical eliminator is reset artificially after its operation and the hydraulic eliminator can be automatically reset.
Source: China Pipes Manufacturer – Yaang Pipe Industry (www.ugsteelmill.com)