The use and maintenance of butterfly valves

1、 Working principle:

The butterfly plate is driven by the Valve stem. If it rotates 90 degrees, it can complete one opening and closing to change the deflection angle of the butterfly plate, which can control the flow rate of the medium. There are two commonly usedbutterfly valves: clamp type butterfly valve and flange type butterfly valve. The clamp type butterfly valve is connected between two pipeline flanges with double headed bolts. The flange type butterfly valve has a flange on the valve, and the flanges on both ends of the valve are connected to the pipeline flange with bolts. Butterfly valve allows fluid velocity: liquid<4.5 meters/sEcond, gas ≤ 20 meters/second.

2、 Direction and position:

Butterfly valves generally do not have directional requirements. If required, it should be determined based on the rotation angle of the butterfly valve and the working principle of the pneumatic actuator. The optimal position for valves installed on horizontal pipelines is vertical installation, and vertical downward movement is not allowed. The installation position of the valve must be convenient for operation: even if the installation is temporarily difficult, consideration should be given to the long-term work of the operator. It is best to align the valve handwheel with the chest, usually 1.2 meters away from the operating floor. This way, opening and closing the valve is more effortless. The handwheel of the landing valve should be facing upwards and not tilted. Valves that rely on walls and equipment should also leave room for operators to stand. Avoid high-altitude operations, especially with acidic, alkaline, toxic media, etc., otherwise it is very unsafe.

3、 Installation task:

1. Be careful during installation and avoid hitting the butterfly valve; Before installation, the valve should be inspected to verify its specifications and identify any damage. Especially for the valve stem, it needs to be rotated a few times to see if it is skewed. During installation, the butterfly valve plate should be stopped in the closed position and any debris inside the valve should be removed; When lifting large valves, the rope should not be tied to the handwheel or valve stem to avoid damaging these components, but should be tied to the flange;
2. When calibrating and tightening the valve (be careful not to tighten it too tightly), the valve should open and close freely, ensuring that there is enough space for the valve to move in the flange to prevent damage to the sealing ring inside the valve, and ensuring that the valve plate has a certain degree of opening. It should be confirmed that the valve plate does not touch the flange and pipeline to avoid jamming after installation.

Maintenance of butterfly valve

When maintaining valves, attention should be paid to whether there is water entering the pneumatic actuator. During the humid season, the accumulated water in the air compressor storage tank causes rust on the transmission mechanism or transmission shaft sleeve. In the cold winter weather, the accumulated water in the air compressor storage tank enters the pneumatic actuator and freezes, causing excessive torque during operation, damaging transmission components, and making manual operation impossible; If forcibly operated, the internal components of the actuator will also be damaged. During maintenance, the discharge valve inside the air compressor storage tank should be periodically opened to drain any accumulated water inside. For butterfly valves with handwheels, after running for about 6 months, open the turbine cover to check if the lubricating oil is normal, and maintain an appropriate amount of lubricating oil.