A control valve is a power operated device capable of modulating flow at varying degrees between minimal flow and full capacity in response to a signal from the controlling system. Control valves play a major role in the everyday effort to increase process plant profitability and conserve energy.
Understanding the Controlling of the Valve
Control valve basically follows the instruction received from controlling loop (sensing element and the controller) Sensing element sends a signal to controller which is intern conveyed to the positioner mounted on the Valve. The Postioner controls the position of the valve through actuator.
Parameters for selection
To select a right fit option following parameter of the media are very important. Such as state (vapour, liquid or two-phase), vapour pressure, flow-prate, inlet and outlet pressures, inlet temperature, density, molecular weight, viscosity, specific heat ratio, critical temperature and critical pressure.
Also, while defining the flow-rate, one should include certain safety margin. One must also consider ambient conditions at site, system geometry, pipeline sizing, MOC, fail-safe position etc.
The most important valve parameter for calculating the size of a control valve is the flow coefficient, Cv. Calculation of Cv depends upon degree of compressibility of fluid
Selecting the Right Valve for your application
based on above, Suitability of the valve type can be defined. There is no single valve type which suits all applications Each type of valve plays a specific role. So it’s important to know which one to choose for the task at hand. Let’s take a look at few Valves that are widely used for control applications
Ideal choice for Good control in case of high differential pressure applications. These Valves are ideal for noise reduction with clean flow media and can also be used for micro flow service.
Maintaining or retrofitting of Globe Valve is easy, which is especially helpful if process conditions change quickly or plant capacity increases marginally.
Butterfly Valves are lightweight, economical solutions and are especially attractive valve solutions in large sizes. Butterfly Valves offer near linear flow and are ideal for instances which require limited pressure drop.
These Valves are a compact and reliable solution for general and even more demanding applications. These valves are widely used in refineries and petrochemical plants, as they can also handle Slurries and viscous fluid. Plug Valves are best suited for applications which require zero residue inside the valve.
Get More out of your Valve
At IPC we believe in detailing every aspect that matters. With our wide of range Valves, we are equipped to support any specific customer requirement.