Basic parameter setting of valve electric device

Basic parameter setting of valve electric device

In terms of domestic valves, the following valve models can be referred to :1. Valve type code Z, J, L, Q, D, G, X, H, A, Y, S respectively: gate valve, globe valve, throttle valve, ball valve, butterfly valve, diaphragm valve, plug valve, check valve, safety valve, pressure reducing valve, trap 2. Valve connection code 1, 2, 4, 6, 7 respectively: 1 internal thread, 2 external thread, 4 flange, 6 welding, 7 pair clamp 3. Transmission mode of the valve code 9, 6, 3 respectively:
In terms of domestic valves, you can refer to the following valve models:
1. The valve type code Z, J, L, Q, D, G, X, H, A, Y, S are indicated respectively:
Gate valve, globe valve, throttle valve, ball valve, butterfly valve, diaphragm valve, plug valve, check valve, safety valve, pressure reducing valve, trap valve
2. Valve connection type code 1, 2, 4, 6, 7 respectively:
1 internal thread, 2 external thread, 4 flanges, 6 welds, 7 pairs of clips
3. Transmission mode of the valve code 9, 6, 3 respectively:
9 electric, 6 pneumatic, 3 worm
4. Material codes of valve body Z, K, Q, T, C, P, R, V are respectively:
Gray cast iron, malleable cast iron, ductile cast iron, copper and alloy, carbon steel, chromium-nickel stainless steel, chromium-molybdenum stainless steel, chromium-molybdenum vanadium steel
5. Seat seal or lining code R, T, X, S, N, F, H, Y, J, M, W respectively
Setting basic parameters of valve electric device
Valve electric actuator
Valve electric device is an indispensable driving equipment to realize remote program control, automatic control and remote control of the valve. Its movement process can be controlled by stroke, torque or axial thrust. Because the valve electric device working characteristics and utilization depends on the type of valve, device working specifications and valve position in the pipeline or equipment.
The electric device generally consists of the following parts:
** motor is characterized by strong overload capacity, large starting torque, small moment of inertia, short time, intermittent work.
Reduction mechanism for reducing the output speed of the motor.
Stroke control mechanism to adjust and accurately control the opening and closing position of the valve.
Torque limiting mechanism for adjusting torque (or thrust) to a predetermined value.
Manual and electric switching mechanism, interlocking mechanism for manual or electric operation.
The opening indicator shows the position of the valve during opening and closing.
First, choose the electric actuator according to the valve type
1. Angle stroke electric actuator (Angle 360 degrees) is suitable for butterfly valve, ball valve, plug valve, etc.
The rotation of the output shaft of the electric actuator is less than one week, that is, less than 360 degrees, usually 90 degrees to realize the valve opening and closing process control. This kind of electric actuator is divided into direct connection type and base crank type according to the different installation interface mode.
A) Directly connected: refers to the form of directly connected installation of the output shaft of the electric actuator and the valve stem.
B) Base crank type: refers to the form in which the output shaft is connected with the valve stem through a crank.
2. Multi-rotary electric actuator (Angle 360 degrees) is suitable for gate valves, globe valves, etc.
The rotation of the output shaft of the electric actuator is greater than one week, that is, it is greater than 360 degrees. It generally needs more than one circle to realize the opening and closing process control of the valve.
3. Straight stroke (straight motion) is suitable for single seat control valve, two seat control valve, etc.
The motion of the output shaft of the electric actuator is linear motion, not rotational.
Two, according to the production process control requirements to determine the control mode of the electric actuator
1. Switching type (open loop control)
Switching electric actuators generally realize the control of the valve on or off. The valve is either in a fully open position or in a fully closed position. This kind of valve does not need to accurately control the medium flow.
It is particularly worth mentioning that switching electric actuators can also be divided into split structure and integrated structure because of the different structural forms. This must be explained when selecting the type, otherwise it often occurs in the field installation and control system *** and other mismatches.
A) Split structure (usually called common type) : the control unit is separated from the electric actuator. The electric actuator cannot control the valve independently, but must be controlled by an external control unit. Generally, the external controller or control cabinet is used for supporting.
The disadvantage of this structure is that it is not convenient for the overall installation of the system, increasing wiring and installation costs, and prone to failure, when the failure occurs, it is not convenient for diagnosis and maintenance, cost-effective is not ideal.
B) Integrated structure (usually referred to as integral type) : the control unit and the electric actuator are packaged as a whole, which can be operated locally without external control unit, and can be operated remotely only by outputting relevant control information.
The advantages of this structure are convenient system overall installation, reduce wiring and installation costs, easy diagnosis and troubleshooting. However, the traditional integrated structure products also have many imperfections, so the intelligent electric actuator is produced.
2. Adjustable type (closed loop control)
The regulating electric actuator not only has the function of switching type integrated structure, but also can accurately control the valve and adjust the medium flow.
A) Control signal type (current, voltage)
The control signal of the regulating electric actuator generally has current signal (4 ~ 20mA, 0 ~ 10mA) or voltage signal (0 ~ 5V, 1 ~ 5V). The type and parameters of the control signal should be clear when selecting the type.
B) Working form (electric on type, electric off type)
The working mode of the regulating electric actuator is generally electric open type (taking the control of 4 ~ 20mA as an example, the electric open type refers to the corresponding 4mA signal is the valve close, the corresponding 20mA valve open), and the other is electric close type (taking the control of 4-20MA as an example, the electric open type refers to the corresponding 4mA signal is the valve open, the corresponding 20mA valve close). Wear-resistant electrode
C) loss of signal protection
Loss of signal protection refers to the loss of control signal due to line faults, the electric actuator will control the valve open and close to the set protection value, the common protection value is fully open, fully closed, keep in situ three situations.
Three, according to the use of the environment and explosion-proof grade classification of electric devices
According to the requirements of the use environment and explosion-proof grade, the electric device of the valve can be divided into ordinary type, outdoor type, flameproof type, outdoor flameproof type.
Determine the output torque of the electric actuator according to the torque required by the valve
Valve opening and closing the required torque determines the output torque of electric actuator to choose how, generally is put forward by the user or by matching valve manufacturer, as the actuator manufacturer is only responsible for the output torque of actuators, normal valve opening and closing the required torque is determined by the valve diameter size and working pressure, but because of the valve manufacturer processing precision, the assembly process, Therefore, the torque required by the same specifications of valves produced by different manufacturers is also different, even if it is the same specification of valves produced by the same valve manufacturer. When the actuator is selected, the torque choice is too small to cause the normal opening and closing of the valve, so the electric actuator must choose a reasonable range of torque.
Four, the correct choice of valve electric device basis:
Operating torque: operating torque is the main parameter of the valve electric device, the output torque of the electric device should be 1.2 ~ 1.5 times of the maximum torque of the valve operation.
Operation thrust: there are two main structure of valve electric device: one is not equipped with thrust plate, direct output torque; The other is equipped with thrust disc, the output torque through the thrust disc stem nut converted into output thrust.