03. ACR-105 UNIT 13 PRACTICE TEST

Electrical, mechanical, electromechanical, digital, and pneumatic are all types of ________.

• fuses

• controls

• circuit boards

• motors

_________ are typically normally closed devices that open their contacts only when the device senses system conditions that are outside the designed operating range.

• Bimetal devices

• Pneumatic controls

• Rod and tube controls

• Safety devices

The main purpose of the HVAC/R industry is to control space or product conditions by controlling _________.

• temperature, humidity, air quality, and air cleanliness

• air quality, air infiltration, and air distribution

• power consumption, temperature, and fuel efficiency

• temperature and power consumption

When a bimetal device is heated, the steel expands faster than the brass, which causes the device to warp.

• True

• False

To make bimetal devices practical over a wider temperature range, ________.

• the bimetal strip is lengthened

• the voltage to the device is modulated

• the device should be mounted perfectly level

• the bimetal strip is shortened

A column of temperature-sensitive fluid rising and falling within a hollow stem in response to a sensed temperature or level of heat intensity best describes the function of a ________.

• thermometer

• pneumatic control

• snap-disc

• thermistor

A ________ is a thin, flexible, movable membrane that is used to convert pressure changes to movement or motion in a control.

• diaphragm

• bimetal coil

• snap-disc

• control bulb

An accordion-like device that expands and contracts when internal pressure (usually vapor) changes is a ________.

• thermocouple

• bellows

• Bourdon tube

• diaphragm

A _______ varies its resistance to current flow based on its temperature.

• thermometer

• thermopile

• thermistor

• thermocouple

If a thermistor increases its resistance as the temperature increases, it has a negative temperature coefficient (NTC).

• True

• False