Why Purchase Process Instrumentation from BCST ?
If you want to find a reliable and stable control valve supplier from China, BCST is your best selection. BCST is one of the leading control valve manufacturers in China, our control valve can meet ANSI, JIS, DIN standards, and we will provide a competitive price based on your project.
BCST will give you the best control valve solution based on your project’s requirements with our professional technical team. If you are a project engineer company that deals with valve and pipe fittings and need to find an OEM control valve manufacturer, then BCST will 100% support you on the valve development.
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- Material test certificates
- Performance test procedure
- Hydrostatic test reports
- Seat leakage and actuator leakage test
- Radiographic test reports
- Liquid Penetration test reports
- Sound Noise Reduction
- Anti-Cavitation Valve Trims
- Outstanding Vibration
- High-pressure Rating
- Big size Available
- Digital Isolation Solution
- Sound protective packaging
What is a control valve?
Control valves are a kind of valve that can regulate and control the flow, pressure, and temperature of a flowing fluid, such as gas, steam, water, or the chemical mixture, by opening or closing internal passages. They control the amount of flow in processes. The valve stem moves, altering the size of passage, which increases, decreases, or holds steady flow.
The control valve body can be categorized as below. The body part of the control valve stays in contact with the products. To handle the temperature, pressure, and chemistry of the medium.
- Globe control valve
1.1 Single-seat globe control valve body
1.2 Double seat globe control valve body
1.3 Balanced plug cage globe control valve body
1.4 Cage guided globe control valve body
1.5 Three-way control valve body
- Angle control valve
2.1 Cage style control valve body
- Rotary control valves
4.1 Butterfly v control valve body
4.2 V-notch ball control valve body
4.3 Eccentric-disk control valve body
4.4 Eccentric-plug control valve body
- Sliding cylinder control valves
- Air-operated valve
6.1 Air-operated valve
6.2 Relay valve
How does the control valve work?
The control valve has three main parts: Control Valve body – in which the modulating element, a globe, plug, ball, or butterfly is contained.
Control Valve actuator -which moves the valve’s modulating elements, such as ball or butterfly
Control Valve positioner- which ensures the valve has reached the required degree of opening. This overcomes the problem of friction and wear.
The control valve actuator is used to move the valve stem. It opens or closes the control valve according to the change required in the flow. We can have linear or rotary actuators for the control valve, depending on the control valve’s body type. For example, a butterfly control valve requires a rotary actuator, and a globe control valve usually works with a linear actuator. The rate of flow through the control valve depends on the pressure difference between the inlet and outlet.
Three different systems to move happen -pneumatic, hydraulic, and electrical for the control valve. Pneumatic actuators of the control valve convert air pressure to a linear or rotary movement. The hydraulic actuator of the control valve does the same with liquids instead of air. And electric actuators of the control valve use motors to convert electrical energy into mechanical torque. All the systems work forward and backward, or indirect or reverse actions. In direct actions, the input will push the actuator down the control valve stem, and the spring with push it back up. The input pushes the valve stem up for reverse auctions, and the spring pushes it back down.
The control valve positioner is to deliver pressurized air to the control valve actuator. Control valve positioners are usually used when a control valve requires throttling action. A control positioner requires position feedback from the control valve stem or shaft and delivers pneumatic pressure to the actuator to open and close the control valve. The positioner should be mounted on or near the control valve assembly. There are three main types of positioners, depending on the type of control signal, the diagnostic capability, and the communication protocol: pneumatic analog or digital.