The straight through single seat regulating valve is composed of parts such as valve body, valve seat, valve core, guide sleeve, valve cover, valve stem, and packing. The valve core and valve stem are connected together. The connection method can be fixed with interference fit pins or threaded connection pins, or the valve stem and valve core of the valve station can be assembled together. A guide sleeve is installed between the valve cover and valve body to guide the upward and downward movement of the valve core. The small hole on the guide sleeve connects the inner chamber of the valve body and the outlet end of the valve. The medium in the upper chamber of the guide sleeve can easily flow into the outlet end of the valve through a small hole, without affecting the movement of the valve core. The valve body of a straight through single seat regulating valve has only one valve core and one valve seat. The characteristic is small leakage and easy to ensure sealing. There are adjustable and cut-off types in structure. Their difference lies in the shape of the valve core. The shape of the regulating valve core is a plunger shape; The shape of the cut-off valve core is flat or conical, and another characteristic of it is the large force exerted by the medium on the valve core, that is, the imbalance force is large, especially in the case of high pressure difference and large diameter, so it is only suitable for low pressure difference situations. Otherwise, actuators with high thrust should be appropriately selected or equipped with valve positioners.

There are two types of straight through single seat regulating valve cores: forward and reverse. When the valve core moves downwards, the flow area between the valve core and the valve seat decreases, which is called positive installation; On the contrary, it is called reverse installation. The nominal size DN and valve seat diameter dN of the regulating valve indicate the size of the valve. For single guide valve cores with a nominal size DN<2.5mm, they can only be installed in the front and not in the back. Therefore, the pneumatic opening type must use a reaction actuator. The flow area of the air open regulating valve increases with the increase of signal pressure; On the other hand, for the gas off type, the flow area decreases with the increase of signal pressure.

A single seat regulating valve is an industrial on-site execution instrument composed of a regulating valve body and different electric actuators. It receives 4-20mA or pulse signals output by the regulator for closed-loop control, achieving automatic control of parameters such as flow, pressure, temperature, liquid level, etc. It can also choose intelligent electric actuators to achieve digital transmission with DCS, PLC, etc., forming a more intelligent control system. There are two types of power supply voltages for electric control valves: 220V and 380V. The flow characteristics of electric control valves include equal percentage, linear, and fast. Compared with pneumatic control valves, electric control valves have the advantages of energy conservation (only consuming electricity during operation), environmental protection (no carbon emissions), fast and convenient installation (without the need for complex pneumatic pipelines and pump workstations), and are widely used in industrial automation systems such as power, chemical, metallurgy, environmental protection, water treatment, light industry, building materials, etc.


Single seat regulating valves are divided into single seat diaphragm regulating valves and single seat piston regulating valves. They use compressed air as the power source, thin film or piston cylinders as actuators, and use accessories such as electrical valve positioners, converters, solenoid valves, and retaining valves to drive the valves, achieving on-off or proportional regulation. They receive control signals from industrial automation control systems to regulate the flow and pressure of pipeline media Various process parameters such as temperature. The characteristics of pneumatic control valves are simple control, fast response, and intrinsic safety, without the need for additional explosion-proof measures. The cost of pneumatic control valves is also lower compared to electric control valves. In fields such as chemical and petrochemical industries, pneumatic control valves have unparalleled advantages over electric control valves.

The single seat regulating valve structure is mainly divided into four types: single seat, sleeve type, double seat, cage type, etc.

The main types of single seat regulating valves are: three-way type, angle type, high-temperature type, low-temperature type, corrugated pipe type, and other types.