Gate Valves

What is Gate Valves?

A gate valve is the most common valve for water supply systems. It represents a linear-motion isolation valve and has a function to stop or allow the flow. Gate valves got their name from the closure element sliding into the flow stream to provide shutoff and, therefore, acting like a gate. Gate valves are used to isolate specific areas of the water supply network during maintenance, repair works, new installations, as well as to reroute water flow throughout the pipeline.

Types of gate valves

Based on construction, gate valves for water supply systems can generally be divided into the following types:

• By wedge: parallel gate valves and wedge gate valves
• By seat: metal seat or resilient seated gate valves
• By stem: with rising or non-rising stem.

Gate valve working principle

Gate valves are normally operated by a handwheel, a valve T-key (wrench) or an actuator. The wheel is attached to a valve stem and transfers rotational energy to it. During the gate valve opening, the rotation of the handwheel turns the threads of the gate stem into the gate and vice versa for closing. This energy moves the gate valve wedge downwards or upwards. In underground gate valve installations, an extension spindle is attached, which allows operation without direct access to the valve itself.

Generally, gate valves are installed in the areas of a pipeline where they will longer remain open or closed, as they generally require sometime to switch between these two positions. However, when the valve needs to be operated quite often or even remotely, motorised gate valves are used (i.e. equipped with an electric actuator).

Gate valve applications

Gate valves have numerous industrial and residential applications.

• Slurries:Gate valves are often used in applications that contain slurries as their media. This is because a gate valve has an unobstructed passageway for the fluid, so the slurry can easily pass through the valve. In addition, knife gate valves can easily cut right through the slurry to close
• Viscous media:Gate valves are commonly used for viscous media like light grease and oils. The unobstructed passageway allows these media to flow easily. The valve can be pigged, a common cleaning method for these applications. In addition, valves for these applications are typically on or off for long periods of time.
• Water gate valves:For water applications, water gate valves are commonly used since flow control is typically not done for these applications. The valve can be fully open or fully closed, allowing for proper water control.