The single-seat regulating valve has a valve core and a valve seat in the valve body, which has the characteristics of small leakage. The valve has a large unbalanced force, and its allowable pressure difference is smaller than that of the double-seat valve. When the pressure difference is high and the diameter is large, it is better to be equipped with a valve positioner. The valve with a nominal diameter ≥25mm is a double-guided structure, and it can be air-opened or air-closed as long as the connection position between the valve stem and the valve core is changed. The single-seat control valve is only suitable for clean medium occasions with strict leakage requirements and small pressure difference. On the contrary, it cannot be used when the medium is not clean and the pressure difference is large. But fine small single seat control valve can be used in these occasions.
The straight-through single-seat regulating valve is composed of valve body, valve seat, valve core, guide sleeve, valve cover, valve stem and packing and other parts. 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 the valve core of the valve station can be integrated. A guide sleeve is arranged between the valve cover and the valve body, which guides the up and down movement of the valve core. The small hole on the guide sleeve communicates with the inner cavity of the valve body and the outlet end of the valve. The medium in the upper cavity of the guide sleeve can easily flow into the valve outlet through the small hole and will not affect the movement of the valve core. There is only one valve core and one valve seat in the valve body of the straight-through single-seat regulating valve. It is characterized by small leakage and easy to ensure sealing. There are adjustment type and cut-off type in structure.
The difference between them is the shape of the spool. The shape of the regulating spool is plunger-shaped; the shape of the cut-off spool is flat or conical. , The case of large diameter is more serious, so it is only suitable for occasions with low pressure difference. Otherwise, an actuator with large thrust should be appropriately selected, or a valve positioner should be used.
The single-seat control valve is an industrial field execution instrument composed of the control valve body and different electric actuators. It accepts the output of the regulator or the pulse signal for closed-loop control, and realizes the control of parameters such as flow, pressure, temperature, and liquid level. Automatic control, and intelligent electric actuators can be selected. There are three kinds of flow characteristics of electric regulating valve: equal percentage, linear and fast. Compared with the pneumatic control valve, the electric control valve has the advantages of energy saving (only consumes electricity when working), environmental protection (no carbon emission), quick and convenient installation (no need for complicated pneumatic pipelines and air pump workstations), etc. It is widely used in electric power, chemical industry, metallurgy, environmental protection, water treatment, light industry, building materials and other industrial automation systems.