Common valves in chemical plants
When the fluid flows through the gate valve, the flow direction does not change. When the gate valve is fully open, the resistance coefficient is almost the smallest of all valves, and the applicable diameter range, pressure and temperature range are very wide. Compared with the stop valve with the same diameter, its installation size is smaller, so it is the most used valve type in chemical production units.
Globe valves are widely used in chemical plants. It has reliable sealing performance and is also suitable for regulating the flow. It is generally installed at the pump outlet, the upstream of the regulating valve bypass flowmeter and other places where the flow needs to be regulated.
When the fluid flows through the valve core of the stop valve, the flow direction changes, so the pressure drop is large, and it is easy to deposit solids on the valve seat, so it is not suitable for suspension. Compared with the gate valve with the same diameter, the volume of the stop valve is larger, which limits its maximum diameter (maximum dnl50 ~ 200).
The three functions are similar, and they are all valves that can be opened and closed quickly. The valve core has a transverse opening, the liquid passes through DC, and the pressure drop is small. It is suitable for suspension or viscous liquid. The valve core can be made into an upper shaped or T-shaped channel to become a three-way or four-way valve. The shape is regular and easy to be made into jacketed valve, which can be easily made into pneumatic or electric valve for remote control.
The difference between the three is that the working pressure of the plunger valve and the ball valve is slightly higher.
It has a certain regulation function, especially suitable for large flow regulation, and the service temperature is limited by the sealing material.
Check valves are generally used to prevent contamination, temperature rise or mechanical damage caused by fluid backflow. The check valve can only be used to prevent sudden backflow, but the sealing performance is poor. Therefore, other measures should be taken for materials strictly prohibited from mixing.
When the inlet of the centrifugal pump is in the suction state, the bottom valve installed at the inlet pipe end in order to maintain the liquid in the pump is also a check valve. When the container is open, the bottom valve can be equipped with a filter screen.
6. Diaphragm valve and pipe clamp valve
When the two valves are used, the fluid only contacts the diaphragm or hose without touching other parts of the valve body. It is especially suitable for corrosive fluid or viscous liquid, suspension, etc. However, the application range is limited by the material of diaphragm or hose.