Intro4u2u

The most common method of opening and closing (actuating) a valve is through a handwheel attached to the yoke or bonnet. This works fine on moderate size valves operating at reasonable pressures, but some severe operating situations call for more muscle. For example, an 18”, class 1500, main steam isolating valve in a power plant operating at 1750 psi and 1000 degrees F. requires a huge amount of torque to open under pressure. The only solution is remote actuation- usually in the form of an electric motor or hydraulic actuator.

Additional gate valve actuation can be provided by pneumatic cylinders. In some cases these sit directly on top of the yoke and are attached directly to the stem, to provide a quick-opening form of actuation. For additional leverage a standard gate valve might have a manual gear operator attached to it to decrease the amount of force required to open and close it under pressure. These devices are called bevel gears.