GATE-CH-2001-1-19-ctrl-1mark

The inherent characteristics of an equal percentage valve relating flow rate \(q\) with valve stem movement \(x\) are described by the equation

• \( \dfrac{dq}{dx} = k\)

• \(\dfrac{dq}{dx} = kq\)

• \( \dfrac{dq}{dx} = \dfrac{k}{q}\)

• \( \dfrac{dq}{dx} = kq^2\)

GATE-CH-2003-80-ctrl-2mark

Temperature control of an exothermic chemical reaction taking place in a CSTR is done with the help of cooling water flowing in a jacket around the reactor. The types of valve and controller action to be recommended are 

• air to open valve with the controller direct acting

• air to close valve with the controller indirect acting

• air to open valve with the controller indirect acting

• air to close valve with the controller direct acting

GATE-CH-2006-20-ctrl-1mark

The control valve characteristics for three types of control valves (P, Q, and R) are given in the figure below. Match the control valve with its characteristics.

• P-Quick opening, & Q-Linear, & R-Equal percentage

• P-Linear, & Q-Square root, & R-Equal percentage

• P-Equal percentage, & Q-Linear, & R-Quick opening

• P-Square root, & Q-Quick opening, & R-Linear

GATE-CH-2006-56-ctrl-2mark

A liquid level control system is configured as shown in the figure below. If the level transmitter (LT) is direct acting and the pneumatic control valve is air-to-open, what kind of control action should the controller (LC) have and why?

• Direct acting since the control valve is direct acting

• Reverse acting since the control valve is reverse acting

• Direct acting since the control valve is reverse acting

• Reverse acting since the control valve is direct acting

GATE-CH-2010-23-ctrl-1mark

Flow measuring instruments with different specifications (zero and span) are available for an application that requires flow rate measurements in the range of 300 litre/h to 400 litre/h. The appropriate instrument for this application is the ONE whose specifications are:

• zero = 175 litre/h, span = 150 litre/h

• zero = 375 litre/h, span = 100 litre/h

• zero = 275 litre/h, span = 150 litre/h

• zero = 475 litre/h, span = 100 litre/h

GATE-CH-2019-24-ctrl-1mark

The liquid flow rate through an equal percentage control valve, when fully open, is 150 gal/min and the corresponding pressure drop is 50 psi. If the specific gravity of the liquid is 0.8, then the valve coefficient, \(C_V\), in gal/(min.psi^0.5) is ________

• Answer

GATE-CH-2016-51-ctrl-2mark

A liquid flows through an "equal percentage" valve at a rate of 2 m³/h when the valve is 10% open. When the valve opens to 20% the flowrate increases to 3 m³/h. Assume that the pressure drop across the valve and the density of the liquid remain constant. When the valve opens to 50%, the flowrate (in m³/h, rounded off to the second decimal place) is _________

• Answer