Electric valve installation attention to detail

Electric valve action than the average distance between the valve, electric valve switching speed can be adjusted, simple structure, easy maintenance, the action of the buffer because of the gas itself, not easy to get stuck and damage, but there must be gas, and its control The system is also more complex than electric valves. This type of valve in the pipeline should be generally horizontal installation. Electric valve device is to achieve program-controlled valves, automatic control and remote control indispensable equipment, the movement process by stroke, torque or axial thrust to control the size. Because the operating characteristics and utilization of the electric valve device depend on the type of valve, the device specifications and the position of the valve on the pipeline or equipment, the correct selection of electric valve device to prevent overloading (work torque higher than the control Torque) is crucial. Normally, the correct choice of electric valve device based on the following: Operating torque Operating torque is the most important parameter to select the electric valve device, electric device output torque should be 1.2 to 1.5 times the maximum torque of the valve operation. Operation Thrust electric valve device host structure there are two: one is not configured thrust plate, the direct output torque; the other is configured thrust plate, the output torque through the thrust plate of the stem nut is converted to output thrust. The number of turns of the output shaft The number of turns of the output shaft of the electric valve device is related to the nominal diameter of the valve, the pitch of the valve stem and the number of threads of the valve. It is calculated as M = H / ZS (M is the total number of rotations Number, H is the valve opening height, S for the stem thread pitch, Z for the stem thread number). Stem Diameter For multi-turn type rodless valves, if the maximum stem diameter allowed by the actuator does not pass through the stem of the fitted valve, it can not be assembled into an electric valve. Therefore, the hollow output shaft of the electric device must have an inner diameter greater than the outer diameter of the stem of the rod valve. For some rotary valves and multi-turn valve in the dark rod valve, though not to consider the passage of the stem diameter, but also should fully consider the stem diameter and keyway size, so that the assembly can work properly. Output speed If the valve opening and closing speed too fast, easy to produce water hammer phenomenon. Therefore, should be based on different conditions of use, select the appropriate opening and closing speed. Electric valve device has its special requirements, that is, must be able to limit the torque or axial force. Usually electric valve device with torque limiting coupling. When the electric device specifications are confirmed, the control torque is also determined. Generally run within a predetermined time, the motor will not be overloaded. However, the following situations may lead to overloading: First, the power supply voltage is low and the required torque can not be obtained, so that the motor stops rotating. Second, the torque limit mechanism is incorrectly set to be greater than the stopping torque, Resulting in continuous generation of excessive torque, the motor stops rotating; Third, intermittent use, the heat savings, exceeding the allowable temperature rise of the motor value; Fourth, for some reason the torque limiting mechanism circuit failure, so that the torque Large; Fifth, the use of ambient temperature is too high, relative to the motor thermal capacity decreased. In the past the way to protect the motor is to use fuses, overcurrent relays, thermal relays, thermostats, etc., but each has its own advantages and disadvantages. This variable-load device for electric devices, there is no absolute reliable protection. Therefore, we must take a variety of combinations, summed up in two ways: First, the increase or decrease of the motor input current to judge; the second is to determine the motor itself fever. Either way, regardless of the type of motor thermal capacity to be given a given amount of time margin. Normally, the basic protection methods of overload are as follows: the overload protection of the motor in continuous operation or inching operation adopts the thermostat; the protection of the motor is locked and the thermal relay is adopted; for the short-circuit accident, the fuse or overcurrent relay is adopted. Related: Electric Valve Routine Maintenance 1, the electric valve should be kept dry and ventilated indoor, both ends of the passage to be blocked. 2, long-term storage of electric valves should be regularly checked to remove dirt, and coated with anti-rust oil on the processing surface. 3, after installation, should be regularly checked, the main inspection items: (1) sealing surface wear and tear. (2) trapezoidal stem and stem nut thread wear. (3) whether the filler is out of date failure, if damaged should be promptly replaced. (4) electric valve repair assembly, the sealing performance test should be carried out.