Manual Butterfly Valve Usage Method

A manual butterfly valve, in simple terms, is a pipeline equipment that controls the opening and closing of the valve through manual rotation of the handle or the worm gear box. It is commonly used in water treatment, HVAC, chemical engineering, etc. It works by rotating the valve plate to regulate the flow or cut off the medium. Although its structure is not very complex, using it correctly leads to a long lifespan and good performance; using it wrongly may result in leakage, or even damage the valve core. Today, let's talk about how to use it properly.

The driving method of the manual butterfly valve directly determines the operation method. The most common ones are handle type and worm gear type.

Handle-type butterfly valve, usually with a smaller diameter, the handwheel or handle is directly connected to the valve stem. When operating, the handwheel is parallel to the pipeline is open, vertical is closed. Some handles are equipped with positioning pins or locking devices to prevent accidental operation. This type of valve has a small opening force, if it is particularly difficult to turn, it is mostly that the valve plate is stuck or there are foreign objects on the sealing surface. Do not forcefully use a wrench to separate it, as it is easy to break the positioning pin.

Worm gear type butterfly valve is commonly used in large-diameter pipelines because it requires a large torque to overcome the medium pressure. Turning the small handwheel on the worm gear box usually requires many turns to complete the stroke. This design itself is "effort-saving in exchange for stroke". When operating, it should be done at a uniform and smooth speed, and avoid rapid and violent shaking to prevent water hammer effect from impacting the pipeline, causing the valve or pipe fittings to vibrate and loosen.

Key step: Valve plate position is more important than the feel

Some experienced workers feel intuitively that "turning all the way down is completely closed". But for a butterfly valve, the valve opening degree is not determined by "turning all the way down". A more reliable approach is to remember the scale on the valve stem or indicator plate. Especially when used for throttling and pressure regulation, it is best to look at the indicator mark of the valve plate position after adjustment to ensure it is consistent with your desired opening degree. If it is controlled by an electric or pneumatic actuator, when operating manually, you must switch back to "manual mode" first, otherwise forcibly turning it may damage the internal gears of the actuator.

Don't forget the medium direction and environment

Before installation, it is necessary to first confirm the flow direction arrow on the valve body to ensure that the arrow direction is consistent with the medium flow direction. If installed in reverse, especially for liquids containing suspended solids, the medium will directly wash the sealing surface, causing the valve to not close tightly and leak quickly. In addition, when the valve is used in an open-air or humid environment, the handwheel, worm gear box, and valve stem should be regularly coated with anti-rust oil, and lubricating grease should be added to the rotating parts to prevent rusting. Especially in winter, if there is water accumulation in the pipeline and the valve is in a half-open state, ice expansion may crack the valve body - it is best to drain the residual liquid when it is not in use.

Closing the door is habit determines the service life

After operation, don't rush to leave. Develop the habit of "resetting": For handle-type valves that are not used for a long time, it is recommended to keep them in the open position to keep the sealing surface in a relaxed state; for worm gear-type valves, make sure the locking cap or locking screw is in place to prevent others from accidentally changing the opening degree. During daily inspections, you can gently touch the flange connection points at both ends of the valve body to check for leakage or moisture, which is the simplest way to detect problems early.