actuator
a device that provides motion to a valve for controlling purposes.
back-pressure regulator
a device used to regulate and/or control the pressure of a process fluid upstream of the device location.
body
the housing component of a valve.
bonnet
is the top portion of the valve body, that connects the valve body to the actuator.
plug
includes the valve stem moves to open or close the flow path through the valve.
handwheel
is used to manually override the actuator or to limit its motion.
I/P tranducer (current-to pneumatic transducer)
a device that converts a milliampere signal into a pneumatic pressure.
pressure-reducing regulator
a device used to regulate and/ or control the pressure of a process fluid downstream of the device location.
regulator
a self-contained and self-actuating controlling device used to regulate variables such as pressure, flow, level, and temperature in a process.
seat
is the stationary part of the valve trim connected to the body that comes in contact with the valve plug.
spring
provides the energy to move the valve in the opposite direction.
stem
is the pushing and pulling rod that transfers the motion of the actuator to the plug.
valve positioner
is to make the valve position match the controller
output.
The stem on the control valve that is sticking_____ rather than moves smoothly.
jumps
A control valve with a spring-and-diaphragm actuator is said to be air-to-close; if there is an air or power loss the valve will:
Be forced completely open by the spring.
During a power failure, you want a valve that is allowing the addition of material to a tank to stop the flow. Therefore, this valve should be a:
Fail-close valve
A (n) ___ is a device that reacts to an instrument signal by creating linear or rotational motion.
actuator
True
A double-acting cylinder type actuator always requires a positioner.
If a control valve and its spring-and-diaphragm actuator are both direct acting, then the control valve will___ if air is lost to it.
Fail open
Which one of the following can a valve positioner do?
reverse the action of the signal received from the controller
What are the three pressure gauges on a pneumatic valve positioner?
signal, output, and supply
a direct-acting positioner on a direct actuator and valve with linear trim will have a linear relationship between the instrument signal and the valve stem positioner produces an output pressure of 9 psi to the actuator.
true
The output signal from a controller can be reversed by which of the following?
the valve positioner
The tag on a pneumatically actuated control valve identifies it as air-to-open. If the positioner has been configured to reverse the signal, then the valve will fail___
closed
In the processing industry, the most common control valve body style is the ___
globe
A butterfly valve is opened with a ___
rotary motion
A three-way valve can be used to ___
divert a flowing stream into two seperate pipes, mix two seperate flowing streams together into one pipe.