What standard should the working atmosphere of electric valve meet? Buy electric valve device need to pay attention to the problem
Electric valve power switch speed can be adjusted, compact structure, easy maintenance, suitable for controlling gas, water, steam, all kinds of corrosive substances, sand, oil, liquid metal and radioactive substances and other types of fluid flow. Electric valve device is an indispensable machine to promote gate valve program control, automatic control and remote control. Its movement can be adjusted by stroke arrangement, torque or radial thrust size. Because the electric valve device working characteristics and utilization rate depends on the electric valve power switch speed can be adjusted, compact structure, easy maintenance, suitable for controlling gas, water, steam, all kinds of corrosive substances, sand, oil, liquid metal and radioactive substances and other types of fluid flow.
Electric valve device is an indispensable machine to promote gate valve program control, automatic control and remote control. Its movement can be adjusted by stroke arrangement, torque or radial thrust size. Because the working characteristics and utilization rate of the electric valve device lies in the valve type, the working system of the device and the position of the gate valve in the pipeline or equipment, the correct selection of the electric valve device is particularly important to avoid the occurrence of overload condition (the working transfer moment is higher than the operating torque).
Because the electric device in the electric valve is a mechanical equipment, its work situation by this work environment harm is very big. Generally speaking, the office environment where the electric valve is located has the following points:
1, with flammable, flammable vapor body or smoke natural environment;
2. Living environment on battleships and new ship ports (with corrosion resistance, aspergillus flavus, damp and cold);
3. Places with strong vibration;
4. Places convenient for fire accidents;
5, cold wet zone, dry tropical climate natural environment;
6, pipeline material temperature as high as 480℃;
7. Indoor installation or outdoor application with preventive measures;
8, outdoor outdoor assembly, cool wind, sand, morning dew, sun corrosion;
9, the operating temperature is less than -20℃;
10. Easy to be immersed in water or soaked in water;
11. Have a natural environment for radioactive elements (nuclear power plants and radioactive element experimental installations);
For the electric valve under the above environment, its electric device structure, materials and preventive measures are different. Therefore, the corresponding valve electric device should be selected according to the above office environment.
Valve electric device is to promote gate valve program control, automatic control and remote control indispensable machine equipment, its movement can be adjusted by travel arrangement, torque or radial thrust size. Because the working characteristics and utilization rate of the valve electric device lies in the valve type, the working system of the device and the position of the gate valve in the pipeline or equipment, the correct selection of the valve electric device is particularly important to avoid overload conditions (working torque is higher than the operating torque).
In general, the important basis for the correct selection of valve electric devices is as follows:
Operating torque: operating torque is the most basic parameter of the valve electric device. The torque derived from the electric device should be 1.2 ~ 1.5 times of the actual operating torque of the gate valve.
Actual operation thrust: the main structure of the valve electric device has two kinds: one is not equipped with thrust disc, immediately exported torque; The other is equipped with a thrust disc and the derived torque is converted to derived thrust according to the stem nut in the thrust disc.
The number of turns of input shaft rotation: the number of turns of input shaft of the valve electric device is related to the nominal diameter of the valve, seat distance and number of screws. It should be calculated according to M = H/ZS (M is the total number of turns of rotation that the electric device should meet, H is the relative height of gate valve opening, S is the screw pitch of the valve seat drive system, and Z is the number of screws of the valve seat). Seat aperture: Multi-rotating open-stem gate valves cannot be installed as electric valves if the electric device allows the requested very large seat aperture to not fit through the stem of the supplied valve. Therefore, the nominal diameter of the hollow input shaft of the electric device must exceed the stem diameter of the open rod valve. For some rotary gate valves and open rod gate valves in multi-rotary gate valves, although there is no need to worry about the problem of seat diameter, the valve seat aperture and groove size should also be taken into account in the selection of assembly, so as to enable normal operation after assembly.
Derived speed ratio: If the opening and closing rate of the valve is too fast, it is easy to produce water percussion phenomenon. Therefore, should be based on different range of application, select the appropriate opening and closing speed. Valve electric devices have special requirements that can limit torque or radial force. General valve electric device use limited torque coupling. When the specification of the electric device is clear, its handling torque may be confirmed. Generally in the pre-determined time operation, the motor is not easy to overload. But if the following conditions may cause overload: first, the power supply current is low, can not get the required torque, so that the motor stops rotating; Second, the torque is incorrectly adjusted to limit the organization, so that it exceeds the stopped torque, resulting in the continuous cause of too much torque, so that the motor stops rotating; Three is intermittent application, the heat deposit, more than the motor allowable temperature increase; Fourth, due to various reasons, the power supply circuit failure of the torque limit organization, so that the torque is too large; Fifth, the temperature of the use scene is too high, and the relativity reduces the thermal conductivity of the motor.
In the past, the protection method of the motor is the application of circuit breaker, over current solenoid valve, heat relay, temperature controller, but these methods have their own advantages. There is no reliable maintenance method for variable load machines such as electric devices. Therefore, a variety of arrangements must be taken, specifically there are two main: one is to judge the adjustment of the motor input current; The second is to judge the burning condition of the motor itself. Both ways, regardless of the class will take into account the thermal conductivity of the motor for a given duration capacity.
In general, what is the most basic maintenance method of overload: overload protection for continuous operation or start operation of the motor, the selection of temperature controller; For the maintenance of motor turns, choose heat relay; For short circuit fault safety accident, choose circuit breaker or over current solenoid valve.
Post time: Feb-24-2023
