Pneumatic Control Systems Quiz

What is an actuator in pneumatic control systems?

• A device that senses a variable other than the controlled variable and sends a feedback signal.

• A mechanical device that operates a final control element such as a valve or damper.

• The actual value of the controlled variable.

• A varying air pressure signal from a controller to an actuator.

What is the main disadvantage of pneumatic control equipment according to the introduction?

• It is inherently proportional but can provide two-position control when required.

• It is suitable where explosion hazards exist.

• It requires people to have the necessary mechanical knowledge.

• It has a high installed cost.

What does a controller do in a pneumatic control system?

• It operates the final control element directly.

• It adjusts the control point of a given controller to compensate for changes in a measured variable.

• It senses the controlled variable or receives an input signal from a remote sensing element, compares the signal with the setpoint, and outputs a control signal (branchline pressure) to an actuator.

• It reverses the compensation effect when switching from summer to winter or vice versa.

What is the purpose of a compensation sensor?

• To operate the final control element such as a valve or damper.

• To control the actual value of the controlled variable.

• To sense a variable other than the controlled variable and sends a feedback signal to the main sensor control point.

• To provide a varying air pressure signal from a controller to an actuator.

What is meant by "direct acting" in the context of pneumatic control systems?

• A device that operates the final control element.

• A thermostat or controller that decreases the branchline pressure on a decrease in the measured variable.

• A thermostat or controller that increases the branchline pressure on an increase in the measured variable and decreases the branchline pressure on a decrease in the variable.

• A process of automatically adjusting the control point of a controller.

What does the term "Manipulated variable" refer to in pneumatic control systems?

• The air line from the air supply system to controllers

• Media or energy controlled to achieve a desired controlled variable condition

• A device that detects and measures the controlled variable

• The variation in the sensed media that causes the sensor output to vary

What is the purpose of a "Restrictor" in an air line?

• It controls the pressure of the air supply

• It detects and measures the controlled variable

• It limits the flow of air

• It provides a setpoint on the controller scale

What is the definition of "Offset" in the context of pneumatic control systems?

• The pressure required to change the controlled variable from 3 to 13 psi

• The difference between the actual system control point and its controller setpoint under stable operating conditions

• The air leaving an air handling system

• A device that responds to changes in temperature and outputs a control signal

What does "N.C." stand for in the abbreviations section?

• Normally connected

• Normally closed

• Normally controlled

• Normally clear

What does "Sensor Span" mean?

• The air line from the air supply system to controllers

• The pressure required to change the controlled variable from 3 to 13 psi

• The variation in the sensed media that causes the sensor output to vary between 3 and 15 psi.

• The value on the controller scale at which the controller is set