Types of Flow Control Valves

As the name depicts, flow control valves are the valves that control the flow of the liquid. These valves may be of simple design, whereas some are complicated closed-loop electro-hydraulic valves. The good thing about these electro-hydraulic valves is that they automatically adjust themselves whenever there is a change in pressure and temperature.

The function of the flow control valve

The primary function of a flow control valve is to regulate speed. The control valves discussed here control the speed of an actuator by regulating the flow rate. Also, with the help of flow rate, it is possible to inquire about the energy transfer rate at any given pressure. So we can say the energy transferred from flow control valves must also equal the work done.

Consequently, the actuator speed is the speed that inquires the rate of energy transfer. Keep in mind that this energy transfer is measured in horsepower, where the speed is considered the function of flow rate.

Different types of flow control valves

1. Gate valve

Gate valves are considered the shut-off valves typically used in the fully open or fully closed position. Gate valves usually consist of seat, stem, disc, valve body, and handle. It is easy to shut off the media with the major parts, such as the seat and stem in the gate valve.

Gate valves have the danger of valve disc vibration; therefore, they are not good fluid regulators. Unfortunately, this disc vibration can damage the disc. But still, gate valves are widely used in industry, and with time, there is an increase in demand for gate valves in the coming years. This is due to the global need for these kinds of industrial valves.

2. Globe valves

Globe valves are also called linear motion valves, and their primary function is to stop, start, and regulate the flow of liquid. With the help of a plug, globe valves close the flow of the liquid.

This plug has a flat or convex bottom lowered onto a horizontal seat present in the center of the valve. So when these values are opened, the plug raises, and the fluid passes through. The good thing about globe valves is that it is easy to remove the valve’s disk from the flow path entirely and then can close the flow path. They are widely used in on, off, and throttling applications.

Globe valves are not like gate valves or plug valves, and thus the type of flow in globe valves can produce slightly higher pressure drops. For this purpose, gate valves must be used in those applications where pressure drop is not a controlling factor.

3. Pinch valves

Pinch valves are affordable flow control valves. The good thing about pinch valves is that they are widely used in slurries or liquids containing significant amounts of suspended solids. In pinch valve seals, flexible elements are used, such as rubber tubes.

These rubber tubes are pinched to turn off the flow. The good thing about rubber sleeves is that they are a wet part of the valve and are flexible enough to allow The Pinch valves to close tightly around the entrapped solids.

For actuating Pinch valves, hydraulic pressure or air pressure is placed directly on the elastomer sleeve. So we can say that the pinch valve works like a built-in actuator. This built-in actuator removes the pneumatic, expensive hydraulic, or electric operators. This is the main reason pinch valves are considered cost-effective valves.

4. Diaphragm valves

As the name depicts, a diaphragm valve has a disc that attaches to a seat. The popular thing about diaphragm valves is that they are flexible enough to respond to any kind of pressure. They can transmit force to open and close the control valve.

Diaphragm valves are just like the pinch valves, which use an elastomeric diaphragm rather than an elastomeric linear in the valve body. This elastomeric diaphragm is attached to the compressor, which then separates the flow stream from the closure element. The diaphragm valves are exceptional for handling corrosive and dirty services.

Most surprisingly, diaphragm valves come with many advantages, such as they offer leak-proof seals and have a tight shut-off. These valves are easy to maintain, do not leak, and are extremely clean. Moreover, they can easily be repaired without interrupting a pipeline.

There are some disadvantages of diaphragm valves. Unfortunately, they can be used only in moderate temperatures, almost -62 to 450 degrees Fahrenheit. The Other disadvantage is that they are only used at moderate pressures of approximately 300 PSI.

5. Needle Valves

Needle valves are specially designed for restricting the flow in small lines. They are famous as volume control valves in which the fluid that moves through the valve turns 90 degrees. This fluid then flows through an orifice which serves as the seat for a cone-shape-tipped rod.

These needle valves have some similarities to globe valves. They have particular design features and have similar benefits. Both the globe valves and needle valves can change the flow rate by using the threaded rotating stem.

However, these valves are different because needle valves are excellent in precision than the globe valves. This is the main reason needle valves are considered to be the best in using calibration applications.

These valves are also used in different industries such as biofuels and petrochemicals. They have finely threaded valve stems, which give them a significant mechanical advantage to be easily sealed by using only minimal force. One of the disadvantages of needle valves is that they do not need only visual inspection to check whether the needle valve is opened or closed.

Other types of flow control valves

Along with these main types, there are also other types of flow control valves.

Butterfly valves

Butterfly valves are very light in weight and take very little space. The good thing about these valves is that they can be used to start the throttling valve. They are favorable for those applications that require a short valve with a bubble-tight seal.

They are usually classified based on the orientation of the butterfly valve seat. Therefore these butterfly valves may be concentric, double eccentric, and triple eccentric. Like the other valves, they are also used in different chemical, pharmaceutical, and food industries.

Non-Return Valve

As the name shows, non-return valves only allow media to flow in one direction. These valves work best in those conditions where there is a danger of reverse flow due to a change in pressure.

Fortunately, non-return valves have many kinds, such as swing type, clapper type, and spring-loaded type. They are considered to be the best at those places where you need backflow prevention in water systems.

Ball Valve 

Ball valves are very popular as they are considered the most commonly used valves in the industry. Most surprisingly, they are used widely to shut off or isolate the media. Based on the ball disc design, these valves may be either floating or trunnion mounted. However, on the other side, they are classified into different types depending on the body style. So the ball valves may be split body, single body, or top entry.

Pressure relief valve

Pressure relief valves are specially designed to open the valve at the high-pressure level and relieve the valve’s excess pressure. This is the main reason they are also called safety relief valves.

So they are accommodating in returning the pressure level to normal. If we talk about the kinds of pressure relief valves, then they come with two types. The names of these valves are direct-acting spring valves and direct-acting dead weight pressure relief valves.

Solenoid valve

Solenoid valves open and close the valves by using electromagnetic actuators. Most surprisingly, they are best in controlling media flow in hydraulic fluid systems and pneumatic fluid systems.

Conclusion

Flow control valves are very popular all over the world and are used in several industries. These all types of flow control valves are useful in controlling backflow, pressure, and temperature.

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