Control valve belongs to the control valve series, the main role is to adjust the pressure, flow, temperature and other parameters of the medium, is the final control element in the process loop. Manual control valves are used to regulate the flow, pressure and level of the medium. According to the signal of the regulating part, automatically control the opening degree of the valve, so as to achieve the regulation of the medium flow, pressure and level.
Control valves are composed of two parts: electric or pneumatic actuators and control valves. The latter has a large flow capacity, small unbalance office and stable operation, so it is usually particularly suitable for high flow, high pressure drop and leakage less occasions. The flow capacity is one of the main parameters for selecting the regulating valve.
When the regulating valve is fully open, the number of flow diameter regulating valve per hour, known as the flow capacity, also known as the flow coefficient. According to the size of the flow capacity value of the table, you can determine the nominal diameter of the regulating valve. Flow characteristics of the control valve, is the pressure difference between the two ends of the valve to maintain a constant condition, the relative flow of the medium through the control valve and its relationship between the opening degree. Control valve flow characteristics are linear characteristics, equal percentage characteristics and parabolic characteristics of three.
The relative stroke and relative flow rate of the equal percentage characteristic is not linear, the change in flow rate caused by the change in the unit stroke at each point of the stroke is proportional to the flow rate at this point, and the percentage change in flow rate is equal. So it has the advantage that when the flow rate is small, the change in flow rate is small, and when the flow rate is large, the change in flow rate is large, which means that it has the same adjustment accuracy at different openings. The linear characteristic has a linear relationship between the relative stroke and the relative flow rate. The change in flow rate caused by the change in unit stroke is constant. When the flow rate is large, the relative value of the flow rate changes little, and when the flow rate is small, the relative value of the flow rate changes a lot. Manual regulating valve category includes throttle valves and pressure reducing valves, whose role is to regulate the pressure of the medium, flow and other parameters.
Single-seat regulating valve, double-seat regulating valve, sleeve regulating valve, angle regulating valve, three-way regulating valve, diaphragm valve, butterfly valve, ball valve, eccentric rotary valve. The first six are straight stroke, the last three are angular stroke. Control valves, used to regulate the flow, pressure and level of the medium. According to the signal from the regulating part, automatically control the opening degree of the valve, so as to achieve the regulation of the medium flow, pressure and level. Control valve is composed of two parts: electric actuator or pneumatic actuator and control valve. The latter has the characteristics of large flow capacity, small unbalance office and stable operation, so it is usually especially suitable for large flow, high pressure drop and leakage less occasions.