The valves commonly used in chemical enterprises include gate valves, globe valves, butterfly valves, ball valves, plug valves, check valves, pressure reducing valves, and drain valves.

1、 Gate valve
Gate valve, also known as gate valve, is a widely used valve. Its closing principle is that the sealing surface of the gate and the sealing surface of the valve seat are highly smooth and consistent, and they are closely attached to each other, which can prevent the flow of medium. The sealing effect is enhanced by relying on the mold shape of the top mold, spring, or gate. It mainly plays a cutting role in the pipeline.
Its advantages are: low fluid resistance, energy-saving opening and closing, can be used in the case of bi-directional flow of media, no directionality, the sealing surface is not easy to erode when fully open, the structural length is short, not only suitable for making small valves, but also suitable for making large valves.
Gate valves are divided into two types based on the stem threads, one is the open stem type and the other is the concealed stem type. According to the structure of the gate, it can be divided into two categories: parallel and mode.
2、 Globe valve
Globe valve, also known as cut-off valve, is the most widely used type of valve. Its popularity is due to the low friction between the sealing surfaces during the opening and closing process, its durability, small opening height, easy manufacturing, and convenient maintenance. It is not only suitable for medium and low pressure, but also for high pressure.
Its closing principle is to rely on the pressure of the valve stem to tightly fit the sealing surface of the valve disc and the sealing surface of the valve seat, preventing the flow of medium.
The shut-off valve only allows one-way flow of medium and has directionality during installation. Its structural length is larger than that of the gate valve, and at the same time, the fluid resistance is high. When operating for a long time, the sealing reliability is not strong.
Globe valves are divided into three types: through type, right angle type, and direct flow oblique globe valves.
3、 Butterfly valve
Butterfly valve, also known as butterfly valve, as the name suggests, its key components are like a butterfly facing the wind and freely spinning.
The disc of a butterfly valve is a disc that rotates around an axis inside the valve seat. The size of the rotation angle is the opening and closing degree of the valve.

Butterfly valves have the characteristic of being lightweight, saving materials compared to other valves. They have a simple structure, quick opening and closing, can be used for cutting and throttling, have low fluid resistance, and are easy to operate. Butterfly valves can be made into large diameters. Where butterfly valves can be used, it is best not to use gate valves because butterfly valves are more economical and have better regulation than gate valves. At present, butterfly valves are widely used in hot water pipelines.

4、 Ball valve
The working principle of a ball valve is to rotate the valve to make it open or closed. Ball valves are lightweight, small in size, and can be made into large diameters. They are reliable in sealing, have a simple structure, and are easy to maintain. The sealing surface and spherical surface are often in a closed state, and are not easily eroded by media. They are widely used in various industries.
Ball valves are divided into two types: floating ball type and fixed ball type.
5、 Plug valve
A plug valve relies on the rotation of the plug body around the centerline of the valve body to achieve the purpose of opening and closing. Its function is to cut off, divide and change the flow direction of the medium. Simple structure, small external dimensions, only need to rotate 90 degrees during operation, The fluid resistance is also not significant. Its disadvantages are that the switch is laborious, the sealing surface is prone to wear and tear, and it is easy to get stuck at high temperatures, which is not suitable for adjusting the flow rate.
Plug valves, also known as cocks, cocks, or rotary valves. There are many types of it, including straight, three-way, and four-way.
6、 Check valve
A check valve is a valve that automatically opens and closes by the force of the fluid itself, and its function is to prevent the backflow of the medium. It has many names, such as check valve, one-way valve, single flow valve, etc. It can be divided into two categories according to structure.
(1) Lift type: The valve disc moves along the vertical centerline of the valve body. There are two types of check valves of this type: one is horizontal, installed in horizontal pipelines, with a valve body shape similar to a globe valve, and the other is vertical, installed in vertical pipelines.
(2) Swing type: The valve disc rotates around the pin axis outside the seat. This type of valve can be divided into single disc, double disc, or multi disc, but the principle is the same.
The suction bottom valve of the water pump suction pipe is a deformation of the check valve, and its structure is the same as the two types of check valves mentioned above, except that its lower end is open to allow water to enter.
7、 Pressure reducing valve
A pressure reducing valve is an automatic valve that reduces the pressure of the medium to a certain value. Generally, the pressure behind the valve should be less than 50% of the pressure before the valve. There are many types of pressure reducing valves, mainly including piston type and spring diaphragm type.
A piston type pressure reducing valve is a valve that reduces pressure through the action of a piston. Spring diaphragm pressure reducing valve relies on spring and diaphragm for pressure balance.
8、 Drain valve
Steam trap, also known as steam drain valve, steam valve, steam trap, return box, return valve, etc. Its function is to automatically discharge the continuously generated condensate without allowing steam to come out.
There are many types of steam traps, including float type, float ball type, bell float type, pulse type, thermal power type, and thermal expansion type. Commonly used types include float, bell float, and thermal power.
(1) The float type drain valve mainly consists of components such as valves, shaft rods, conduits, floats, and casings.
When the condensed water in the equipment or pipeline is pushed into the drain valve by steam pressure and gradually increases to near full filling of the float, the weight of the float exceeds the buoyancy and sinks downwards, causing the throttle valve to open. This allows the condensed water inside the cylinder to be discharged through pipes and valves under the action of steam pressure. When the condensate inside the float is close to being discharged, it rises upwards due to the weight reduction of the float, causing the throttle valve to close and the condensate begins to accumulate inside the float. This periodic operation not only automatically discharges condensate, but also prevents steam from escaping.
(2) Bell shaped float type drain valve
Bell shaped float type drain valve, also known as bucket type drain valve (Mainly composed of components such as regulating valves, buckets, casings, and filtration devices. The buckets inside the drain valve are inverted and initially in the descending position. The regulating valve is open. When cold air and condensate in the equipment or pipeline are pushed into the drain valve by steam pressure, they are then discharged by the regulating valve. On the one hand, when steam and a small amount of air that has not been discharged gradually fill the internal volume of the bucket, and condensate continues to accumulate, the bucket is Generate buoyancy and rise, causing the regulating valve to close and stopping the discharge of condensate. On the other hand, a small portion of the steam and air inside the bucket are discharged from the small holes at the top of the bucket, while most of the heat dissipates and condenses into liquid, gradually reducing the buoyancy of the bucket and causing it to fall, opening the regulating valve and discharging the condensed water. This periodic operation not only automatically discharges condensate, but also prevents steam from escaping.
(3) Thermodynamic drain valve
When the condensate water in the equipment or pipeline flows into the air blocking drainage valve, the steam in the transformer chamber condenses and reduces the pressure. The force under the valve plate is greater than that above, so the valve plate is lifted. Due to the higher viscosity and lower flow rate of condensed water compared to steam, it is not easy to create negative pressure between the valve plate and the valve bottom. At the same time, condensed water is not easy to flow into the transformer chamber through the gap between the valve plate and the shell, keeping the valve plate open. The condensed water is discharged through the circular groove.
When the steam in the equipment or pipeline flows into the drain valve, due to the lower viscosity and higher flow rate of steam compared to condensate, negative pressure is easily caused between the valve plate and the valve seat. At the same time, some steam flows into the pressure chamber, causing the force on the valve plate to be greater than the force on the bottom, causing the valve plate to quickly close. This periodic operation not only automatically discharges condensate, but also prevents steam from escaping.