If the valve actuator is too small, the side cannot produce enough torque to fully operate the valve. Generally speaking, we think that the required operating torque of the valve comes from the friction between the metal parts of the valve (such as ball core, disc) and the seal (seat). Many factors affect the operating torque of the valve, such as operating temperature, operating frequency, pipeline and pressure difference, and flow medium (lubrication, drying, mud).

Operating torque of ball valve

The structural principle of electric ball valve is basically based on the fact that a polished ball core (including channel) is sandwiched between two seats (upstream and downstream). The rotation of the valve ball core * * or flows through the ball center, and the force generated by the pressure difference between upstream and downstream makes the ball core close to the downstream seat (floating ball valve structure). In this case, the torque of operating the valve is determined by the friction between the ball core and the valve seat, and between the valve stem and the packing. The maximum moment occurs when there is a pressure difference and the ball core rotates towards the open direction in the closed position.

Operating torque of butterfly valve

The structural principle of electric butterfly valve is basically based on the butterfly plate fixed on the axis. In the closed position, the butterfly plate is completely sealed with the valve seat. When the butterfly plate rotates (around the valve stem) and is parallel to the flow direction of the fluid, the valve is in the fully open position. On the contrary, when the butterfly plate is perpendicular to the flow direction of the fluid, the valve is in the closed position. The moment of operation of butterfly valve is determined by the friction between butterfly plate and valve seat, stem and packing, and the force of pressure difference acting on butterfly plate also affects the moment of operation. When the valve is closed, the torque is the largest, and it will be significantly reduced after small rotation.

Operating torque of plug valve

The structure principle of electric plug valve is based on the plug sealed in the conical plug body. There is a passage in one direction of the plug of the plug valve. As the plug is screwed into the valve seat, the valve can be opened and closed. The operating torque is usually not affected by fluid pressure but is determined by the friction between the seat and plug during opening and closing. The plug valve has the maximum torque when it is closed. Due to the influence of pressure, the torque is always high during the remaining operation.