What is a gate valve?GATE VALVES ARE WIDELY USED FOR ALL TYPES OF APPLICATIONS AND ARE SUITABLE FOR BOTH ABOVE GROUND AND UNDERGROUND INSTALLATION. NOT LEAST FOR UNDERGROUND INSTALLATIONS IT IS PARAMOUNT TO CHOOSE THE RIGHT TYPE OF VALVE TO AVOID HIGH REPLACEMENT COSTS.
Gate valves are designed for fully open or fully closed service. They are installed in pipelines as isolating valves, and should not be used as control or regulating valves. Operation of a gate valve is performed doing an either clockwise to close (CTC) or clockwise to open (CTO) rotating motion of the stem. When operating the valve stem, the gate moves up- or downwards on the threaded part of the stem.
Gate valves are often used when minimum pressure loss and a free bore is needed. When fully open, a typical gate valve has no obstruction in the flow path resulting in a very low pressure loss, and this design makes it possible to use a pipe-cleaning pig. A gate valve is a multiturn valve meaning that the operation of the valve is done by means of a threaded stem. As the valve has to turn multiple times to go from open to closed position, the slow operation also prevents water hammer effects.
Gate valves can be used for a vast number of fluids. Neelcon's gate valves are suitable under the following working conditions:
Potable water, wastewater and neutral liquids: temperature between -20 and +70 °C, maximum 5 m/s flow velocity and up to 16 bar differential pressure.
Gas: temperature between -20 and +60 °C, maximum 20 m/s flow velocity and up to 16 bar differential pressure.
Parallel vs wedge-shaped gate valvesGate valves can be divided into two main types: Parallel and wedge-shaped. The parallel gate valves use a flat gate between two parallel seats, and a popular type is the knife gate valve designed with a sharp edge on the bottom of the gate. The wedge-shaped gate valves use two inclined seats and a slightly mismatched inclined gate.
A gate valve, also known as a sluice valve, is a valve which opens by lifting a round or rectangular gate/wedge out of the path of the fluid. Gate ValvesGate Valves are primarily designed to start or stop flow, and when a straight-line flow of fluid and minimum flow restriction are needed. In service, these valves generally are either fully open or fully closed.
The disk of a gate valve is completely removed when the valve is fully open; the disk is fully drawn up into the valve bonnet. This leaves an opening for flow through the valve at the same inside diameter as the pipe system in which the valve is installed.
Advantages of using gate valves:
Good shutoff features
Gate Valves are bidirectional and therefore they can be used in two directions
Pressure loss through the valve is minimal
The major drawbacks to the use of a gate valve are:
They can not be quickly opened or closed
Gate Valves are not suitable for regulate or throttle flow
They are sensitive to vibration in the open state
|Main design of butterfly valves|
The butterfly valve can be centric or eccentric. On a centric (concentric) butterfly valve the stem is centered in the middle of the disc and the disc centered in the bore. The eccentric butterfly valve has one or more stems (stub shafts) located offset from the center according to the categories of single, double and triple offset valves.