Which type of positioner is commonly used with the feedwater control valve?

Which type of positioner is commonly used with the feedwater control valve?

• A. Direct acting
• B. Reverse acting
• C. Variable acting
• D. Constant acting

Answer: (B)

The type of positioner commonly used with the feedwater control valve is reverse acting. This is due to how the positioner and valve operate together to control the flow of water into the boiler system. A reverse acting positioner is designed to increase the output signal when the input signal decreases. This is particularly important in the context of a feedwater control valve, which is responsible for maintaining the appropriate water level in the boiler. As the steam pressure in the boiler increases, the demand for feedwater decreases. The reverse acting positioner responds to this by reducing the valve opening, restricting the flow of water into the boiler when less feedwater is needed. This type of control ensures that the boiler operates efficiently and safely, preventing potential issues like flooding or low water levels. Other types of positioners, such as direct acting, would not perform optimally in this situation as they work in the opposite manner, increasing flow with increased signal input. Variable acting and constant acting positioners typically refer to different characteristics of control mechanisms that do not apply specifically to the feedwater control context, making them less suitable for this application.

The type of positioner commonly used with the feedwater control valve is reverse acting. This is due to how the positioner and valve operate together to control the flow of water into the boiler system. A reverse acting positioner is designed to increase the output signal when the input signal decreases. This is particularly important in the context of a feedwater control valve, which is responsible for maintaining the appropriate water level in the boiler.

As the steam pressure in the boiler increases, the demand for feedwater decreases. The reverse acting positioner responds to this by reducing the valve opening, restricting the flow of water into the boiler when less feedwater is needed. This type of control ensures that the boiler operates efficiently and safely, preventing potential issues like flooding or low water levels.

Other types of positioners, such as direct acting, would not perform optimally in this situation as they work in the opposite manner, increasing flow with increased signal input. Variable acting and constant acting positioners typically refer to different characteristics of control mechanisms that do not apply specifically to the feedwater control context, making them less suitable for this application.