level measurement

2, February 2018

A Few Things About Control Valves

A control valve is a valve used to control fluid flow by varying the size of the flow passage as guided by a signal from a controller. This enables the control of flow rate and the consequential control of process quantities like pressure, temperature, and fluid level. Electrical, hydraulic or pneumatic actuators usually perform the opening or closing of automatic control valves. Normally using a modulating valve, which is set to any position between fully open and fully closed, valve positioners are used to make sure the valve attains the level of opening. Are you searching for temperature measurement? Browse the before talked about website.

Air-actuated valves are generally used because of their simplicity, as they only require a compressed air source, whereas electrically-operated valves require cabling and switchgear, and valves needed high-pressure supply and return lines to the hydraulic fluid. A variety of control operation and valve types exist. But, there are two chief forms of action; the action and the sliding stem. The most common and versatile kinds of control valves are V-notch ball a sliding-stem world, butterfly and angle types. Their popularity the many options available and derives from rugged structure which make them suitable for a variety of process applications.

It’s used primarily for throttling purposes. It may be considered a general purpose flow control valve high temp program. Faster to open or close, a most reliable form of seats, throttling to control the flow to any degree. The most common control element from the process control industries is the control valve. The control valve manipulates a fluid, such as gas, steam, water, or chemical compounds, to compensate for the load disturbance and maintain the controlled process variable as close as possible to the desired set point. Control valves might be the most important, but sometimes the most neglected, part of a control loop. The reason is usually the instrument engineer’s unfamiliarity with regions of engineering disciplines such as mechanics, metallurgy, noise control, and piping and vessel design, terminologies, and the aspects that can be involved depending on the severity of service conditions.

Any control loop usually consists of a sensor of the process condition, a transmitter and a controller that compares the “process variable” obtained from the transmitter with the “set point,” i.e., the desirable process condition. The controller, in turn, sends a corrective signal to the “final control element,” the final part of the loop and the “muscle” of the process control system. While the sensors of the process variables are the eyes, the controller the mind the control element is the hands of the control loop. This makes it the most important, alas sometimes the least understood, part of an automatic control system. This comes about due to our strong attachment to computers and electronic systems causing some fail in the proper understanding and proper use of the hardware.