Choosing a solenoid valve suitable for plastic extruder can consider the following aspects:
1. Economy: On the premise of meeting demand, choose products with more economical prices, but can not only pursue low prices and ignore quality.
2. Safety: According to the actual working conditions, to ensure that the solenoid valve has the corresponding safety performance. For example, if the working environment does not allow water, it is necessary to choose a waterproof solenoid valve, which can usually be customized according to customer requirements. The nominal nominal pressure of the solenoid valve should be higher than the maximum pressure in the pipeline to prevent shortening the service life or other unexpected conditions. For corrosive fluids, all stainless steel or slf solenoid valves suitable for highly corrosive media should be selected. If you are in an explosive environment, you must choose the corresponding explosion-proof level of the product.
3. Reliability: Select according to working hours and frequency. Normally closed type (power on, power off) is generally selected, but in the case of a long opening time and a short closing time, normally open type should be selected. Because there is no professional standard for solenoid valve in China, the life test usually belongs to the type test project, so it is necessary to be careful when selecting solenoid valve manufacturers. When the action time is short and the frequency is high, the direct action type is generally selected. In the case of large caliber, the fast series is selected.
4. Applicability:
Media matching: Ensure that the fluid in the pipeline is consistent with the media labeled in the selected solenoid valve series model.
Suitable temperature: the temperature of the fluid must be less than the nominal temperature of the solenoid valve.
Viscosity requirements: Pay attention to the liquid viscosity allowed by the solenoid valve, generally below 20cst, if greater than 20cst should be specifically noted.
Pressure difference consideration: When the working pressure difference is less than 0.04mpa, can choose such as zs, 2w, zqdf, zcm and other direct acting or step by step direct acting solenoid valve; When the working pressure difference is greater than 0.04mpa, the pilot type (differential pressure) solenoid valve can be selected, but the maximum working pressure cannot exceed the maximum calibrated pressure of the solenoid valve. General solenoid valve for one-way work, pay attention to whether there is a reverse pressure difference, if so, you need to install a check valve.
Cleanliness requirements: If the fluid cleanliness is not high, the filter should be installed in front of the solenoid valve, because usually the solenoid valve has higher cleanliness requirements for the medium.
Other aspects: pay attention to the flow aperture and nozzle caliber, if necessary, bypass pipe can be set to facilitate maintenance. When there is water hammer phenomenon, to adjust the opening and closing time of the solenoid valve. In addition, it is also necessary to consider the impact of the ambient temperature on the solenoid valve, the current and power consumption of the power supply should be selected according to the output capacity, usually allowed in the range of ±10%, AC startup should pay attention to the va value.
