To reduce the required manual effort applied or to minimize the pressure shocks a wormgear is preffered. A wormgear allows greater ease of operation and gives a better protection against system damage caused by waterhammer due to quick closing.
For regulating valves with a wormgear the system can be properly balanced by fine manual control. Casing materials are ductile iron or cast iron. The available operating devices for wormgear are handwheels, tee caps for buried service or chainwheels for overhead installations.
Function - Open / close
Control

Parameter Name	Parameter Value
Type	worm
Teeth	straight-toothed
Other characteristics	cast iron