List of Questions and answers on Control Valves and Accessories used in industrial measurement and control.
-
State the combinations of pneumatic actuator and globe valve body required
to provide:
a) air to open action;
b) air to close action. -
State and sketch the three flow characteristics for the most common globe
valves. -
State a typical application for each of the three flow characteristics and
explain why it is the most appropriate selection for that application. -
State the effect of unbalanced force on valve position and explain with an
example, how bench setting would correct this problem. -
Briefly explain at least three advantages a positioner gives when it is used
in conjunction with a control valve. -
Describe the fail state for a given valve.
-
Sketch and describe a system pump head vs flow curve set to define
installed valve differential conditions. -
Explain, with a diagram, how a three-way solenoid valve can be used for
ON/OFF control of a pneumatic valve. -
State the formula which describes a control valve Cv factor. What is the Cv
for a valve which will pass a water flow of 100 USGPM with a pressure drop
of 25 psi? What flow would this valve pass when the pressure drop is 49
psi? -
State why it is often advisable to use different sized valves in parallel when
the process variable has a very large flow range.
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