More than a century has past since industrial valves were invented. To meet the needs of different applications, valves have evolved into nine major types. There are 9 types of industrial applications and services covered by these types.
There are several factors to consider when categorizing valves. According to their functions, valves are categorized in this article. Depending on the valve design, some take only one, while most take two.
As part of the quarter-turn valve family, butterfly valves are also included. There is a flat to a concave disc attached to the stem of a butterfly valve that distinguishes it from other valves.
The disc blocks media flow when the valve is closed by being positioned in the middle or attached to one side of the valve stem. Discs are supported by the stem. The butterfly valve throttles when it is incrementally opened.
- The design is compact.
- It is lightweight.
- There is a minimal drop in pressure.
- Installation is easy.
- Throttling capabilities are limited.
- Disk movement may be affected by strong pressure.
Water and gas applications often require butterfly valves to isolate or interrupt media flow. Large diameter pipes are well suited for butterfly valves. It is also possible to perform slurries, cryogenics, and vacuum services with them.
The check valve is opened and closed by internal pressure instead of external action. The main function of a check valve also called a non-return valve, is to prevent backflow.
- The design is simple.
- Human intervention is not require.
- Prevent backflow effectively.
- Serves as a backup system.
- Doesn’t work well for throttling.
- The disc can get stuck in the open position.
Pumps and compressors use check valves to prevent backflow. Check valves are often use in steam boiler feed pumps. Check valves are also use in a variety of processes in chemical and power plants. When there are several gases in one pipeline, check valves are also use.
Shut off/on valves also include gate valves. Its linear disc movement makes it unique. There is either a gate-shaped disc or a wedge-shaped disc with an effective shut-off and on mechanism. Isolation is the primary purpose of gate valves.
Even though it is possible to use it as a throttling valve, this is not recommend due to the possibility of damaging the disc. Throttling applications using half-closed gate valves can damage the disc due to the surge of the media.
- There is no media flow resistance since the gate does not obstruct the flow when fully opened.
- It can use in bi-directional flows as well.
- The design is simple.
- Suitable for large diameter pipes.
- They are not good throttlers because they cannot control them accurately.
- When used for throttling, media flow intensity may damage the gate or disc.
Any application can benefit from gate valves. They are suitable for wastewater applications and neutral liquids. Gate valves can handle gases with a maximum pressure of 16 bar and a temperature between -200C and 700C. Slurries and powder media handle with knife gate valves.
Also, read Solenoid Valve: How Does It Work?
The ball valve belongs to the quarter-turn valve family. A ball valve’s distinctive feature is its hollow ball-shaped disc that stops or starts media flow. As one of the quickest valves, the ball disc opens and closes with just a quarter turn.
- Easily shuts off and on.
- Wear & tear is minimal if adequately used.
- The cost of maintenance is low.
- The pressure drop is minimal.
- Cost-effective in terms of time and labor.
- Cannot be used as a control or throttling valve.
- The valve disc and seat could be damaged by sedimentation in thicker media.
- Rapid closing and opening could cause surge pressure.
Fluid, gaseous, and vapor applications requiring bubble-tight shutoff can use ball valves. In addition to being primarily used in low-pressure applications, ball valves with metal seats are also used in high-pressure and high-temperature applications.
The globe valve looks like a globe with a plug-type disc attached. Linear motion valves belong to this family. Globe valves are great to turn off/on valves, but they are also excellent throttling valves.
In a similar manner to gate valves, globe valve discs move up unimpeded to let media pass through. For applications that do not require high-pressure drops, this is a great valve alternative.
- The gate valve has a better shutting mechanism.
- Despite frequent use, wear and tear are not an issue.
- It is easy to disassemble and repair.
- The media flow path may obstruct, resulting in high-pressure loss
- High-pressure applications are not recommend.
Globe valves perform well when leakage is a major concern. Globe valves use for high point vents and low point drains. Also, globe valves work when pressure drop is not an issue. Globe valves use in applications requiring regulated flow, such as cooling water systems.
Globe valves use in feedwater systems, chemical feed systems, and extraction drain systems.
The needle valve is name after its needle-like disc. The mechanism is similar to that of a globe valve. In smaller piping systems, needle valves provide more precision and control. In low flow rates, needle valves are still part of the quarter-turn family.
- Controls fluid media effectively.
- Ideal for vacuum services or precision systems.
- A minimal amount of mechanical force require to seal the valve.
- Shut-off applications that require more sophistication are the only ones that use it.
- It takes quite a few turns to turn it off and on completion.
Fluid surges and precise fluid flow control by needle valves in instruments. In calibration applications, needle valves are more common use. In pipe systems, needle valves use as media regulators at distribution points.
The pinch valve is another valve use for stop/start and throttling. The pinch valve belongs to the linear motion valve family. Media flow is unobstructed due to the linear motion. The pinch tube inside the valve controls the flow of fluid by pinching.
- The design is simple and does not contain any internal moving parts.
- Suitable for slurries and thicker, even corrosive media.
- Prevents contamination of media.
- Maintenance costs are low.
- High-pressure applications is not recommend.
- Gases should not use with this product.
Typically, pinch valves use for unrestricted fluid flow. Slurry applications are the most suitable for them. Applications requiring complete isolation from valve parts and environmental contaminants benefit from pinch valves.
Pinch valves are also use in wastewater treatment, chemical processing, and cement handling, among others.
Plug valves belong to the quarter-turn valve family. Its uses as a bubble-tight shut-off for plugs and cylinders. Due to its taper end, it is appropriately name as the plug valve. A ball valve’s mechanism is similar to its closing and opening mechanism.
- The mechanism is simple.
- In-line maintenance is easy.
- There is a low-pressure drop.
- Capability to seal reliably and tightly.
- Fast-acting as only a quarter-turn need to open or close.
Plug valves are effective shut-off and on valves. Plug valves use in a variety of applications. Gas pipelines, slurries, applications with high levels of debris, and applications with high temperatures and pressures fall into this category.
Sewage systems benefit from these valves. Since plug valves do not come into contact with the media, they are also ideal for highly corrosive and abrasive media.
Pressure Relief Valve
Relief valves are design to maintain pressure balance and avoid buildup by releasing or limiting pressure from pipelines. It is sometimes mistakenly referr to as a pressure safety valve.
It serves to protect the equipment from overpressure or to increase pressure when there is a pressure drop. If the pressure exceeds a preset level, the valve will release extra pressure.
- It can use in all types of gas and liquid applications.
- Can also use at high pressures and temperatures.
- It is cost-effective.
- There is a problem with the spring mechanism and the corrosive material.
- There is a possibility that back pressure could affect valve functions.
When back pressure is not a major concern, pressure relief valves are effective. A pressure relief valve is commonly found in boilers and pressure vessels.
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