WHAT IS A CONTROL VALVE?
To regulate fluid flow, a control valve changes the size or course of the flow in response to a controller’s signal. This helps regulate other vital processes such as temperature, liquid level, and pressure by directly controlling the flow rate. The final control element is also known as the ‘final control element’ in automatic control terminology. We are the leading valve supplier in Bahrain.
Control valves are used to control flow, pressure, liquid level, and temperature by opening or closing them in response to signals received from controllers. Positioners control the closing and opening of the actuators, while electric, hydraulic, and pneumatic actuators control the opening and closing of the control valve.
HOW DOES IT WORK?
To deliver consistent quality products, there are numerous control loops in the process plant. To maintain the required operating range, these control loops have a set pressure, temperature, flow, and level. The sensors and transmitters in each control loop measure the disturbances caused by internal disturbances. Once the information has been collected, the controllers determine what needs to be done to rectify the load disturbances. Analyzing, measuring, comparing, and calculating the data collected is the first step in implementing a control element. Here is where the control valve comes into play and reduces these disturbances.
Control valves work by manipulating the flowing fluids, such as water, gas, steam, or chemical compounds, to minimize the load disturbance and regulate the process variable to the nearest value of the desired set point.
VALUES CATEGORIZATION: ITS ADVANTAGES AND DISADVANTAGES
Valve stems can be classified as linear or rotary based on their movement. Furthermore, it can be classified into the following categories based on the services it offers:
We have Gate, Diaphragm Ball, Plug, and Butterfly valves for ON-OFF services.
For THROTTLING SERVICES – Globes, Diaphragms, Butterfly Pumps, and Pinch Pumps
Check valves for NON-REVERSE FLOW
The gate valve consists of a flat barrier that can be adjusted to control the flow area. With an on-off function, it is most suitable for regulating high temperatures and pressures for various liquid flows. In addition to the automatic emergency shutoff valves, this design is also used for hand-operated valves.
Aira Euro Automation is the leading Valve Supplier in Bahrain. We offer various types of industrial valves like ball valves, butterfly valves, control valves, plug valves, and many more.
ADVANTAGES OF GATE VALVE
- The closing feature is good
- Both ways can be used in a circuit
- As a result, there is very little loss of pressure because of laminar flow
DISADVANTAGES OF GATE VALVES
- There is a delay between closing and opening the feature.
- It takes a lot of space to assemble these valves, erect them, start them, and maintain them.
- When operating at a high temperature that fluctuates periodically, the system is susceptible to leakage.
- Vibrations are created.
Globe valves are used for throttling purposes, and the term ‘globe’ refers to their exterior shape. Globe valves feature a stem that moves linearly up and down to adjust the plug’s position. In addition to its short stem travel and high seating capability, it also has a large pressure drop and high flow controllability.
ADVANTAGES OF GLOBE VALVE
- Has a good feature for full closing.
- Compared to gate valves, smaller strokes lead to faster opening and closing times.
- The throttling feature is good.
- With little change in shaft disconnection, this valve can be used as a stop check valve.
DISADVANTAGES OF GLOBE VALVE
- Compared to gate valves, there is a higher pressure loss.
- To close under high pressure, the actuator must have greater torque.
The plug valve consists of a plug, body, and cover and use primarily in refineries, chemical plants, and petrochemical plants. They are usually small in size, require little headroom, and come in a wide range of materials. A tight shut-off, quick opening, and low-pressure drop are provided by them
- The design is simple and it consists of a few parts.
- Easy to open and close.
- At the place of operation, it can easily maintain and repair.
- Their low flow resistance makes them leak-proof and reliable
DISADVANTAGES OF PLUG VALVES
- Due to the fast movement, it creates high friction and requires a lot of force.
- The conic plug usually narrows flows at valve transitions.
- It is more expensive than ball valves.
Ball valves use to control the pressure and flow of corrosive fluids, normal liquids and gases, and also slurries. Temperature and pressure are also regular.
ADVANTAGES OF BALL VALVES
- Provides leak-proof service.
- Service that opens and closes quickly.
- Compared to gate valves, it has a very small size.
- Compared to gate valves, it is lightweight.
- Designed with multi-way flexibility to reduce the number of valves required.
- Under high temperature and pressure conditions, it provides reliable and safe service.
- As compared to gate valves and globe valves, this valve requires less force to open and close.
DISADVANTAGES OF BALL VALVES
- This is not an appropriate solution for permanent throttling. Because the residual fluid collides and sticks to the base, it can cause leaks, abrasions, and other problems.
Under low temperature and pressure conditions, corrosive fluids require diaphragm valves. As a result of the force applied from the stem, the diaphragm valve varies the flow resistance.
DIAPHRAGM VALVES ADVANTAGES
- Working parts completely isolate from process fluids in the diaphragm.
- Construction is simple, making it easier to operate and maintain.
- Simple construction and ease of operation make it hassle-free to operate.
- This device can use for opening, throttling, and closing.
- As a result of the internal sheathing of the body, it provides good chemical resistance.
- There is no shaft leakage since the fluid remains isolated from the bonnet group.
- Suitable for heavy chemicals, chemicals, and radioactive fluids.
- As the fluid remains isolated from the bonnet group, it prevents microbial contamination, so it is suitable for the food, pharmaceutical, and beer industries.
DISADVANTAGES OF DIAPHRAGM VALVES
- As the valve transition has set, the pipeline cannot discharge completely.
- The diaphragm material determines the operating temperature and pressure.
- Applied hydrostatic pressure to the diaphragm has a limit.
- Diaphragm valves have limited dimensions.