A valve actuator
a) cannot be reverse acting
b) will always have one side of the diaphragm open to atmosphere
c) is a two-position device
d) position is a function of controller output
e) causes a valve to always fail open
Answer: D
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Power Engineering Chapter 86
- When a recorder receives a signal from a transmitter, the recorder incorporates a
- A proportional only controller
- The output pressure signal of a transmitter relay is usually
- A flapper-nozzle assembly is basic to all
- On a basic pneumatic transmitter, a movement of the flapper towards nozzle will:
- Putting a controller on manual control means:
- A valve which gives good throttling action, takes less actuator force, but does not seal well is a:
- A proportional-only controller:
- Most solenoid valves operate so that the upstream line pressure will:
- Cascade control utilizes:
- A circular chart recorder:
- A sensing element sends its signal to
- A CRT or LCD display trend recorder
- A CRT trend display:
- A pneumatically actuated control valve which opens on air failure has a:
- A recorder utilizing a spiral Bourdon tube will have a pen movement:
- Normally-closed solenoid operated valves open when
- In a pneumatic control system, the nozzle receives a regulated air supply pressure of approximately:
- A control valve that has one plug that moves upward to close the port is called:
- A two-position controller compares conditions to a set point and:
- Integral and Derivative functions
- When controller output is proportional to the amount of deviation, the controller is:
- A valve body that seals on the down stroke is:
- A proportional controller: