Manually operated reducers use manpower to reduce the force required to manually operate the valve. There are usually two types of multi-turn and part-turn. It has the characteristics of simple structure and convenient operation. Usually used to drive valves with a diameter less than 300 mm nominal diameter.
Pneumatic (liquid) device.
Pneumatic (liquid) devices are mostly composed of pressure cylinders driven by compressed gas or hydraulic pressure, and a few are composed of deceleration mechanisms driven by pneumatic or hydraulic motors. The former is widely used for partial rotation and linear reciprocating transmission, the latter can be used for multi-turn rotation transmission, and some can also be used for electric devices. These all have the characteristics of compact structure and rapid opening and closing, and are suitable for indoor or corrosive, flammable, and corrosive environments. The disadvantage of pressure solenoid valves is that the piping is relatively complicated and remote control is not suitable. The pressure of the aerodynamic device is generally (4~6)×105 Pa, and its output power is not large. The hydraulic mechanism adopts higher pressure and the output power is larger.
A device that uses a motor to drive a reducer, which drives the valve through the reducer. Some valves are driven by electromagnetic force. There are two types of multi-turn and part-turn. It has the characteristics of convenient power supply, easy adjustment, large output, suitable for remote control and automatic control, and wide range of use. However, in the design and manufacturing process, it is necessary to consider the impact of outdoor and flammable and explosive environmental conditions on the electric device. The structure of the water meter solenoid valve is relatively complicated.
Gas-liquid combined device and electro-hydraulic combined device.
The pneumatic, electric, and hydraulic linkage device is composed of a hydraulic mechanism with compressed gas or electric power as the power source. Generally it is a part-rotation type, which has the characteristics of fast action, large output, and can drive large-diameter valves. This type of equipment is usually used on shut-off valves or emergency automatic shut-off valves on long-distance oil and gas pipelines.