Gate Valve Pedestals
To provide remote control functions of gate valves installed at depth they can be fitted with a pedestal assembly and extension.
As a rule, gate valves are actuated either manually or electrically. The pedestal assembly for manually actuated gate valves includes the actuator and the stem extension. The pedestal assembly for the electrically actuated gate valves consists of the following parts: yoke, stem extension, drive adapter, drive shaft and camshaft.
The operation principle of the pedestal assembly is as follows: the pedestal is installed aboveground; the drive shaft rotates inside the pedestal and transmits the torque from the handwheel or electric actuator through the stem extension to the gate valve, opening or closing the gate. Bearings can be installed inside the pedestal to ease shaft rotation. In most cases, the pedestal is installed in-line with the gate valve, but there are additional devices that can be installed to allow actuator operation when the pedestal is mounted at a sharp angle to the valve or when there is horizontal displacement between them.
Depending on operating conditions, pedestals are constructed of various materials: steel 20, steel 09Г2С or stainless steel.
Gate valves can be converted for remote control without dismantling. For that purpose, the handwheel is connected to the stem extension with special clamps. To connect the gate valve and the electric actuator the actuator is removed and then installed on the yoke sleeve of the pedestal.
In recent years, stem extensions have been widely used for cast iron wedge gate valves. Stem extensions can have either a fixed or an adjustable height. They are constructed in accordance with the standards of DIN/EN. Stem extensions are mostly applied to direct buried and underground valves in water supply systems, firefighting and wastewater treatment facilities.