Unit 13 Quiz

Question 1

Bimetal used to sense temperature changes in some applications.

Answer 1

Snap disc

Question 2

Two unlike metals joined together at one end, when heated on the fastened end, will produce an electrical current flow. What is it?

Answer 2

Thermocouple

Question 3

Thin flexible metal disc with a large area that will flex up and down due to pressure changes.

Answer 3

Diaphragm

Question 4

Device used to control/maintain space or product temperature.

Answer 4

Thermostat

Question 5

Multiple thermocouples wired in series.

Answer 5

Thermopiles

Question 6

Bimetal device used to sense water heater temperatures.

Answer 6

Rod and tube

Question 7

Varies its resistance to current flow based on its temperature.

Answer 7

Thermistor

Question 8

Modulating controls are used to.

Answer 8

Vary the speed of a motor

Question 9

A thermal system overload may occur if a specific electrical or mechanical component is not cooled properly, resulting in.

Answer 9

Overheating

Question 10

An example of a Bimetal device is a.

Answer 10

Snap disc

Question 11

A thermocouple is a device that.

Answer 11

Converts heat into electrical energy.

Question 12

Adding length to a Bimetal element is done by shaping the element into a coil, helix hairpin or

Answer 12

Worm shape

Question 13

True or False: The major advantage of a remote bulb control is that the control body can be located outside the controlled area for better access.

Answer 13

True

Question 14

True or false: A PTC thermistor’s resistance decreases as temperature increases.

Answer 14

False

Question 15

True or false: Fluid expansion is a way to sense temperature change.

Answer 15

True

Question 16

True or false: Bellows are normally used with vapor instead of a liquid inside it.

Answer 16

True

Question 17

True or false: A properly operating thermocouple connected to a solenoid in a gas valve should put out 20 to 30 millivolts.

Answer 17

True

Question 18

True or false: A thermistor is a device that produces voltage across the hot and cold junctions when heated.

Answer 18

False

Question 19

True or false: The system overload control may be electrical, thermal or a combination of both.

Answer 19

True

Question 20

True or false: Vapor is more sensitive to temperature change.

Answer 20

False

Question 21

True or false: Safety devices are typically normally closed as long as the system is operating properly.

Answer 21

True

Question 22

True or false: The metal tube in the rod-and-tube control expands and contracts faster than the steel rod.

Answer 22

True

Question 23

True or false: An increase in pressure under the diaphragm causes it to expand inward.

Answer 23

False

Question 24

Controls can be classified as _____,_______,_________,__________,__________,and_______________.

Answer 24

Electrical
Mechanical
Electromechanical
Electronic
Digital
Pneumatic

Question 25

Name two kinds of fluid expansion controls.

Answer 25

Diaphragm
Bellows

Question 26

Name two types of snap-action mechanisms.

Answer 26

Magnet
Over puddle of mercury
Over center device

Question 27

The output from a pressure transducer is typically a value of.

Answer 27

Resistance
Capacitance
Inductance

Question 28

If a thermistor’s resistance decreases as the temperature increases, it has a ______ temperature coefficient.

Answer 28

Negative

Question 29

Bimetal controls are limited in application by what?

Answer 29

The amount of warp that can be accomplished with a temperature change.

Question 30

This device can be wired in parallel with a motor start capacitor to cut out the start capacitor once the motor has started.

Answer 30

PTC Thermistor