Chapter 39 Flashcards
A final element is a device that receives a control signal and \_\_ the amount of material or energy in a process. A. Regulates B. Increases C. Decreases D.Pressurizes
A final element is a device that receives a control signal and __ the amount of material or energy in a process.
A normally open valve does not allow pressurized fluid to flow out of the valve in the spring-actuated (de-energized) position.
T OR F
A three-way mixing globe valve has one inlet and two outlets.
T OR F
Cavitation causes wear patterns in a valve that resemble a sanded and polished surface.
T OR F
Cavitation is the process where vapor bubbles in a flowing liquid collapse inside a control valve
T OR F
If the critical pressure ratio for air flowing through a valve is 0.527 and the actual pressure ratio is 0.477, then a choked flow condition exists.
T OR F
A ball valve is a throttling valve consisting of a straight-through valve body enclosing a ball with a hole through it.
T OR F
Actuators designed for rotary valves and for dampers typically have shorter strokes than actuators for sliding stem valves.
T OR F
The amount of movement of the diaphragm in a diaphragm -and-spring actuator is determined by the ___.
FILL IN BLANK
In a reverse-acting actuator, the valve plug moves toward the seat when air is applied.
T OR F
An advantage of a pneumatic sliding stem piston actuator is that higher air pressures can be used to provide greater power to a valve.
T OR F
