What is Control Valve?
A control valve is a device that regulates the flow of fluids by changing the size of the flow tube. This device allows you to control flow, temperature, pressure, and liquid level directly.
Working Principle of Control Valve
The opening and closing of a control valve is done by either pneumatic or hydraulic actuators, electrical actuators.
Air actuated valves are commonly used because they are simple to operate and simply require compressed air, whereas electrically controlled valves require additional switch gear and cabling, and hydraulically actuated valves require return lines for hydraulic fluid and high pressure supplies.
Calibration of Control Valve
Materials required for control valve calibration:
- Data Sheet
- Portable Pneumatic Calibrator
PROCEDURE
• The first step is to ask the panel administrator to put the controller in manual mode of the control loop.
• Isolate the control valve from the process (must be done by the on-site operator)
• Verify the range of the input signal, that is, 0.2 to 1.0 Kg/cm2.
• Then calculate the time. That is the difference between the upper and lower limits (1.00.2 = 0.8).
• Now divide it into four equal parts, because 0.2 is 25% of the interval.
• Check the valve stroke according to the input signal given.
• Now divide it into 4 equal parts, which is 25% (0.2-inch valve stroke is 0.5 inch).
• Now increase the interval value to 0.2. That is, 0.2 + 0.2 = 0.4 kg / cm2.
• Check that the valve travel is 25% (0.5 inches). If not, an error will occur.
• The total value of 1 Kg / cm2 is now used to obtain a full 2-inch stroke.
• As mentioned above, if you find any difference in the readings, adjust the spring accordingly.
