Due to different variables, there cannot be a universal valve. Therefore, to meet the changing requirements of the industrial process applications, countless designs and variants have been created over the years as new materials have been developed. All valve types fall into nine categories: Plug Valves, Gate Valves, Globe Valves, Ball Valves.
Ball valves (Flanged/ Threaded Ball Valve)
They are basically modified plug valves. They are not satisfactory for throttling, they are quick to operate, easy to maintain, require no lubrication, produce a tight seal with low torque, and their pressure drop is a function of the size of the orifice.
The ball valve, also known as a quick-closing valve, or ball valve. It is a very versatile type of valve because the lever only needs to be turned 90 degrees to close or open the valve quickly.
This valve is popular in the industry due to its ease of operation and small design.
It is an excellent option when fluid regulation is not required, as this type of valve operates best when fully closed or fully open. Because, when left partially open, the fluid and its pressure would cause damage to the interior of the valve with time.
Butterfly Valve (Lug/Wafer Type Butterfly Valve)
The butterfly valve is characterized by its circular shape and the disc in its center. The lever is rotated 90 degrees to open or close the disc which in turn blocks the flow of fluid.
There are different types of butterfly valves that are categorized according to their installation method, the most common is the wafer and the Lug (shown in the image).
This valve is a good option for applications that do not require to withstand a lot of pressure and do not need regulation Because the butterfly valve also operates fully open or closed, it is an excellent option to be installed in places with little space, or in process lines that do not support too much weight.
They work at pressures of 150 psi to vacuum. Valves that do not allow reverse flow (check) act automatically on pressure changes to avoid reversal of flow, such as the check valve, for example.
They are one of the most common and oldest known types. They are simple, lightweight, and inexpensive, and the cost to maintain is also low because they have a minimum of moving parts.
The primary use of butterfly valves is for shutoff and throttle service when handling large volumes of gases, and liquids at relatively low pressures.
The needle valve is the most accurate of the valves found in this article. They are basically globe valves that have needle-like conical taps that fit precisely into their seats. They are generally used for instruments or hydraulic systems.
This type of valve is characterized by having a fine operating mechanism since, when the handwheel is turned, a needle-shaped stem descends that gradually regulates the fluid with fine and precise throttling.
This valve is useful for high-pressure applications, high temperatures, or sanitary and instrumentation requirements.
Construction materials are typically bronze, stainless steel, brass, and other alloys.
The primary use of plug valves, like gate valves, is in shut-off, non-throttling service. Since the flow through the valve is smooth and uninterrupted, there is little turbulence within the valve and therefore the pressure drop is low.
The main advantages of the plug valves are fast action, simple operation, minimal space for installation, and tight shut-off.
There are two main types of plug valves:
- Lubricated type plug valves to prevent leakage between the plug surface and the seat on the body and to reduce friction during rotation.
- Non-lubricated plug valves have a coating that eliminates the need for lubrication.
- Plug valve services include full opening or closing without throttling.
- They have minimal resistance to flow.
- They are intended for frequent operation.