Controls-Part A

Question 1

Characteristics of a controlled system. What are the 4 main variables of interest.

Answer 1

1) temperature
2) pressure
3) liquid level
4) rate of flow

Question 2

When temperatures or any other variable is determined by in direct means, it’s value is said to be?

Answer 2

Inferred

Question 3

A controlled system is made up of all the equipment in which the controlled variable exists. This includes all of the automatic control equipment. T of F

Answer 3

False, dose not included all of the automatic control equipment.

Question 4

An example of a direct means of measurement is using a pressure gauge to calculate the height of liquid in a vessel. T or F

Answer 4

False, a direct means would be a level column.

Question 5

An example of a primary element is the float in a low water cut-off that senses the height of boikerbin a steam boiler.

Answer 5

False

Question 6

In a cascade system, there is generally a (major) inner loop and a (minor) outer loop.

Answer 6

False

Question 7

A closed loop system gives feedback on the isolated controlled area back to the controller.

Answer 7

True

Question 8

What is a pneumatic operator?

Answer 8

Pressure activated device

Question 9

What are two types of pneumatic operators

Answer 9

A). Dampers
B). Valves

Question 10

Define the following terms.
A). Normally open
B). Normally closed

Answer 10

A). The valve or control device returns to the open position when there is 0 psig air pressure in the diaphragm chamber.
B). The valve or control devic4 returns to a closed position when there I’d 0 psig air pressure in the diaphragm chamber

Question 11

In a parallel operation, the spring ranges for the final operator will open and close__________

Answer 11

Together

Question 12

On a direct acting controller, when the temperature increases the pressure on the output signal_________

Answer 12

Increase

Question 13

On a reverse acting controller, when the temperature decreases, the pressure on the output signal_________<

Answer 13

Increases

Question 14

The type of controller that can continually exhaust pranch-line control air is a _______ ________

Answer 14

Bleed type

Question 15

When moving a dial on a thermostat to 31°C (70°F), your adjusting the ____________

Answer 15

Setpoint

Question 16

An auxiliary device is usually found between the controller and the final element. T or F

Answer 16

True

Question 17

An electronic to pneumatic relay converts a pneumatic signal into an eletric signal. TorF

Answer 17

False

Question 18

A bias start relay us used to sequence overlapping spring ranges on the final elements. T or F

Answer 18

False

Question 19

A positive-positioner is used in a control-valve operator to increase the stroking speed. T or F

Answer 19

False

Question 20

One of the primary importance of instrumentation is?

Answer 20

Pressure

Question 21

A device that will give a direct measurement is a ?

Answer 21

Gauge glass

Question 22

An example of a type of indicator is a?

Answer 22

Bipedal strip

Question 23

Using a direct acting controller and a normally closed valve; as the temperature rises the NC valve will.

Answer 23

Open

Question 24

The maximum pressure setting on an instrument air main is.

Answer 24

25 psi

Question 25

The type of controller that exausts from the branch- line only while reducing the branch-line pressure is.

Answer 25

Non-bleed type

Question 26

Two positions contollers are also called

Answer 26

Positive-acting

Question 27

A volume booster is useful on a

Answer 27

Final element

Question 28

In cols freezing condition that are effecting a heating coil, the primary function of a freeze- stat is to

Answer 28

Shut down fans.

Question 29

They type of element that is normally used as a freeze-stat is

Answer 29

Averaging sensor