How to install pneumatic control valve and installation principles

How-to-install-pneumatic-control-valve-and-installation-principles

1. In order to ensure the safety and reliability of the control valve, horizontal installation shall be adopted as far as possible, and the length of 10D straight pipe section shall be ensured before and after the valve, and installation in places with high vibration intensity shall be avoided. If the pump outlet is located, try to extend the pipeline to avoid damage to the control valve.

2. Make sure that the regulating valve and the process pipeline are in the same straight line, and keep the actuator vertical.

3. Stud bolts shall be used. The gasket shall be a metal spiral wound gasket that can be reused for many times to ensure the sealing reliability of the regulating valve.

4. Ensure sufficient maintenance space for the regulating valve in future use. Generally, the regulating valve is equipped with a negative line, which can be switched in case of emergency. However, when installing the negative line, attention should be paid to leaving a certain maintenance space for the regulating valve, which is generally not less than 50cm.

5. Replace the valve core and valve seat. For the regulating valve with handwheel mechanism, turn the handwheel mechanism to the limit position, loosen the cross connecting block between the regulating valve push rod and the valve core with a special hexagonal wrench, and disconnect the actuator from the valve core. Loosen the upper bonnet screws and take down the entire upper bonnet together with the actuator.

The valve core and valve seat can be replaced with special tools, and then replaced with new valve core and valve seat.

6. Replace the actuator: pay attention to the vertical (vertical) or horizontal (bedroom) system of the air tank during installation. The cylinder must move up and down freely without jamming. In order to facilitate maintenance and overhaul, the starting actuator shall be installed near the ground or floor. When the valve positioner or the first wheel mechanism is installed, the convenience of observation, adjustment and operation shall be ensured. The function of the first wheel mechanism is that it can be used to directly manually operate the control valve without pneumatic drive in case of an accident.

The starting actuator shall be installed at the place where the ambient temperature is not higher than+60 ℃ and not lower than - 40 ℃, and shall be far away from the equipment with large vibration. To avoid thermal aging of the diaphragm, the distance between the upper diaphragm cover of the control valve and the heat carrying pipeline or equipment shall be greater than 200mm If the nominal diameter of the valve is different from that of the pipe, a reducer shall be added between them. The pneumatic actuator shall be vertically installed on the horizontal pipeline. If it is necessary to install horizontally or obliquely under special circumstances, it shall be generally supported except for small caliber valves. Even if the valve is installed vertically, it shall be supported when the valve has large dead weight and vibration.

The direction of fluid passing through the control valve shall be marked on the valve body and shall not be installed reversely, just as the orifice plate cannot be installed reversely.

A shut-off valve is installed at the front and back of the control valve to facilitate the removal of the control valve during repair.

Before the installation of control valve, the pipeline shall be cleaned to remove dirt and welding slag. After installation, the pipes and valves shall be cleaned again, and the sealing performance of the joints between valves and pipes shall be checked. When the medium is introduced for the first time, the valve shall be in the fully open position to avoid the magazine from being stuck.

Installation principle

1. The installation position of the pneumatic control valve shall be at a certain height from the ground, and a certain space shall be reserved at the top and bottom of the valve to facilitate the disassembly and repair of the valve. For the control valve equipped with pneumatic valve positioner and hand wheel, easy operation, observation and adjustment must be ensured.

2. The regulating valve shall be installed on the horizontal pipeline and perpendicular to the pipeline. Generally, it shall be supported under the valve to ensure stability and reliability. For special occasions, when the control valve needs to be installed horizontally on the vertical pipeline, the control valve should also be supported (except for small caliber control valve). During installation, avoid additional stress on the regulating valve).

3. The working environment temperature of the regulating valve shall be no more than 95% and 95% respectively at (- 30~+60) relative humidity.

4. There should be straight pipe sections at the front and back of the control valve, with a length of no less than 10 times the pipe diameter (10D), to avoid that the straight pipe section of the valve is too short to affect the flow characteristics.

5. If the caliber of the regulating valve is different from that of the process pipe, the reducing pipe shall be used for connection. When installing small caliber control valve, threaded connection can be used. The fluid direction arrow on the valve body shall be consistent with the fluid direction.

6. Bypass pipe shall be set. The purpose is to facilitate switching or manual operation, and the control valve can be overhauled without shutdown.

7. Before the installation of the regulating valve, completely remove the foreign matters in the pipeline, such as dirt, welding slag, etc.