What is the difference between handle lever butterfly valve and worm gear butterfly valve? How

Both the handle lever butterfly valve and the worm gear butterfly valve are valves that need to be operated manually, commonly known as manual butterfly valves, but they are still different in use.

1.  The handle lever rod of the handle lever butterfly valve directly drives the valve plate, and the switch is fast but laborious;    the worm gear butterfly valve drives the valve plate through the worm gear, and the switch is slow but labor-saving. Therefore, when the pressure in the pipeline is large, it will be very laborious to choose a handle lever butterfly valve.

2.  The butterfly valve commonly used in engineering is generally the worm gear butterfly valve, because in addition to labor saving, its sealing performance is also better than that of the handle lever butterfly valve, especially in the environment with high switching frequency, the service life of the worm gear butterfly valve will be higher than that of the handle lever butterfly valve.

3.  The handle lever butterfly valve is generally used more with small diameter (within DN200), because generally the small diameter butterfly valve has a smaller torque and can be opened and closed directly by hand, while the worm gear butterfly valve uses a gearbox to drive the valve stem to rotate, which is more labor-saving.

Selection principle of handle lever drive and worm drive
When the valve stem torque is greater than 300N·M, it is driven by a gear box, and the rest are generally driven by a handle lever.