The medium transported in various pipelines in the chemical industry usually has a certain degree of corrosiveness, such as sulfuric acid, hydrochloric acid, nitric acid, and other corrosive media. All corrosion prevention is the most basic requirement for chemical equipment. Chemical valves are no exception, and the selection of valve materials must be corrosion-resistant.What are the commonly used valves in chemical plants?
1、 Gate valve
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 among all valves, and the applicable caliber range, pressure and temperature range are very wide. Compared with globe valves of the same caliber, their installation size is smaller, making them the most commonly used valve type in chemical production equipment.
2、 Shut-off valve
Stop valves are widely used valve types in chemical plants. It has reliable sealing performance and is also suitable for regulating flow. It is generally installed at the pump outlet, upstream of the regulating valve bypass flow meter, and other places where flow needs to be adjusted.
When the fluid flows through the shut-off valve core, it changes its flow direction, resulting in a large pressure drop and easy deposition of solids on the valve seat. Therefore, it is not suitable for suspension. Compared with gate valves of the same caliber, globe valves have a larger volume, which limits their caliber (DNl50-200).
3、 Plug valve, plunger valve, ball valve
The three functions are similar, and they are all valves that can be quickly opened and closed. The valve core has a horizontal opening, allowing liquid to flow directly through and reducing pressure drop, making it suitable for suspension or viscous liquids. The valve core can also be made into an upper or T-shaped channel to become a three-way or four-way valve. The appearance is neat and easy to make into a jacketed valve for situations that require insulation. These types of valves can be easily made into pneumatic or electric valves for remote control.
The difference between the three is that the working pressure of plunger valves and ball valves is slightly higher.
4、 Butterfly valve
It has certain adjustment functions, especially suitable for high flow regulation, and the use temperature is limited by the sealing material.
5、 Check valve
Check valves are generally used to prevent contamination, temperature rise, or mechanical damage caused by fluid backflow. Check valves can only be used to prevent sudden backflow but have poor sealing performance. Therefore, for materials strictly prohibited from mixing, other measures should also be taken.
When the inlet of a centrifugal pump is in the suction state, the bottom valve installed at the inlet pipe end to maintain the liquid inside the pump is also a check valve. When the container is open, the bottom valve can be equipped with a filter.
6、 Diaphragm valve and pipe clamp valve
When using these two types of valves, the fluid only comes into contact with the diaphragm or hose and does not touch other parts of the valve body, making them particularly suitable for corrosive fluids, viscous liquids, suspensions, etc. However, the scope of use is limited by the material of the diaphragm or hose.
