1. What are the differenct types of gate valves?
There are three ways to classify a gate valve, by the type of disk, body bonnet joint and stem movement.
Types of disk include:
Solid taper wedge
Flexible wedge
Split wedge or Parallel disks Valve
Types of Body Bonnet Joint include:
Screwed Bonnet
Bolted-Bonnet
Welded-Bonnet
Pressure-Seal Bonnet
Types of Stem movement include:
Rising Stem
Non-rising Stem
2. What is the difference between a rising stem gate valve and a non-rising stem gate valve?
There are two main ways to differentiate between a rising stem gate valve and a non-rising stem gate valve. The first is appearance; rising stem gate valves are typically made from cast or forged steel, while non-rising stem gate valves are usually brass, bronze, or cast iron. There is also a difference in size; non-rising takes up less space, whereas the rising type requires more space. The second is the ascension of the valve stem. It's easy to spot whether the valve is closed or open on a rising stem gate valve by looking at the amount of stem that is exposed; if it is a lot, the valve is open. Whereas the stem of the non-rising stem gate valve only rotates and does not move up and down.
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