The conventional water production process of a waterworks is inseparable from the use of valves from raw water intake, flocculation and sedimentation in sedimentation tanks, filtration in filter tanks, and output of water supply from the final water pump station. The tap water supply system is that the tap water plant transports the treated water to various water points through the municipal water transmission and distribution network. This process sometimes requires secondary pressurization. However, the selection requirements for valves are quite different in different parts. The main difference lies in the caliber of the valve, the type of the valve and the control method of the valve.
The pipelines are pressure transmission pipelines, and the most used ones are gate valves, globe valves, ball valves, butterfly valves, check valves, soft joints, etc. The coating and internal treatment of each valve must meet the requirements of drinking water sanitation permits.
1. Determine the process requirements, that is, determine the pressure and flow in the on-site pipeline. According to the caliber of the pipeline and on-site working conditions, select the type of valve, combine the process parameters of the first step, select the valve, and decide whether to install an extension pipe according to the installation position of the valve.
2. Select the transmission mechanism according to the transmission form. The butterfly valves in water plants are mostly multi-turn rotation mechanisms, and the gate valves are linear transmission mechanisms. To determine the control method, for the air control system, it is the choice of the cylinder and the supporting transmission mechanism, and for the electric control system, it is the choice of the electric actuator. The selection of the electric actuator is to determine the speed ratio and output torque of the transmission mechanism, the interface type, and the speed and power of the motor according to the full stroke time required by the valve, the torque of the valve and other parameters.
3. Consider the protection level and communication method of the actuator, and whether to choose other configurations such as silicon controlled rectifiers. With the improvement of the automation level, the water plant has higher and higher requirements for valves, and more and more, but no matter how it changes, the conventional selection is roughly within the scope of this article. The main valves are mentioned in this article. Of course, the water plant also uses exhaust valves, solenoid valves, etc., so I won’t introduce them in detail here.
4. When the pipe diameter is not greater than 50mm, a stop valve should be used, and when the pipe diameter is greater than 50mm, a gate valve or butterfly valve should be used.
5. Regulating valves and stop valves should be used when the flow and water pressure need to be adjusted.
6. Gate valves should be used for parts requiring small water flow resistance (such as on the water pump suction pipe).
7. Gate valves and butterfly valves should be used on pipe sections where water needs to flow in both directions, and stop valves are not allowed.
8. Butterfly valves and ball valves should be used for parts with small installation space.
9. Stop valves should be used on the pipeline sections that are often opened and closed.
10. A multi-functional valve should be used on the outlet pipe of the water pump with a larger diameter.