Classification of Valves Based on Their Function And Purpose

Classification of valves based on their function and purpose

1. Block valve: A block valve, also known as a closed circuit valve, whose core function is to connect or block the medium in the pipeline. This type of valve includes gate valves, globe valves, plug valves, ball valves, butterfly valves, and diaphragm valves. Gate valves control the on/off of media by lifting and lowering the gate, which has the characteristics of low fluid resistance, small opening and closing force, and is suitable for cutting or connecting large-diameter pipelines; Globe valves rely on the lifting and lowering of the valve disc to open and close the channel, and are usually used in situations where flow regulation requirements are not high but the medium needs to be tightly cut off; Plug valves use a cone plug or ball to rotate around their own centerline to control the flow of media, with quick opening and closing. They are commonly used in pipeline systems with medium and low pressure, small diameter, and low medium temperature; Ball valves use the 90 degree rotation of the sphere to cut off or conduct media, with good sealing and strong flow capacity, and are widely used under various pressure and temperature conditions; Butterfly valves operate by rotating around a fixed axis inside the valve seat through a disc. They have a simple structure, small size, and light weight, and are commonly used in large-diameter, medium low pressure water supply and drainage, and ventilation duct systems; Diaphragm valves use diaphragms to separate the valve body cavity from the medium, and control the on/off of the medium through the lifting and lowering of the diaphragm. They are suitable for transporting corrosive media or pipeline systems with high hygiene requirements.

2. Check valve: Check valve, also known as one-way valve or check valve, its core function is to prevent the backflow of medium in the pipeline. For example, the bottom valve at the suction end of a water pump belongs to the category of check valves. This type of valve can ensure that the medium flows in one direction in the pipeline, thereby protecting the equipment from the impact and damage of the reverse flow medium. Common check valves include lift check valves and swing check valves. The valve disc of the lift check valve rises and falls along the vertical centerline of the valve body, suitable for small-diameter pipelines; The valve disc of the rotary check valve rotates around the axis outside the seat, which has a large flow capacity and is suitable for medium and large diameter pipelines with low pressure loss requirements.

3. Safety valve: Safety valves are mainly used to prevent the medium pressure in pipelines or devices from exceeding the specified value, thereby achieving safety protection. When the system pressure exceeds the set value, the safety valve will automatically open to release excess pressure and automatically close after the pressure returns to normal. Safety valves can be divided into various types such as spring type, lever type, and pulse type. Among them, spring type safety valves are widely used, while lever type safety valves are suitable for high-pressure and large-diameter applications. Pulse type safety valves are commonly used in high-pressure and large capacity boilers and other equipment, and the main safety valve is driven to operate by the opening of the pulse valve.

   
   

4. Regulating valves: Regulating valves include regulating valves, throttle valves, and pressure reducing valves, mainly used to regulate the pressure, flow rate, and other parameters of the medium. Regulating valves can receive external control signals and automatically change the valve opening to accurately control the medium flow rate. They are commonly used in automation control systems in industries such as chemical, petroleum, and power; The throttle valve adjusts the flow rate by changing the cross-sectional area of the channel; And the pressure reducing valve can automatically reduce the inlet pressure to a certain required outlet pressure and maintain stability.

   
   

5. Diverter valve: Diverter valves include various distribution valves and drain valves, which are used to distribute, separate, or mix media in pipelines. Distribution valves can distribute a medium in a predetermined proportion to multiple branch pipelines or mix different media; And drain valves are used to automatically remove condensed water from steam pipelines and prevent steam leakage to ensure efficient operation of steam systems. They are widely used in steam heating, steam power and other equipment to effectively improve energy utilization efficiency and prevent water hammer from damaging pipelines and equipment.