ACR108: Unit 13 Practice Test (CRF) - Mr. Graham

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

• circuit boards

• controls

• fuses

• motors

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

• Safety devices

• Rod & tube controls

• Pneumatic controls

• Bimetal devices

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

• power consumption, temperature, and fuel efficiency

• air quality, air infiltration, and air distribution

• temperature and power consumption

• temperature, humidity, air quality, and air cleanliness

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 voltage to the device is modulated

• the device should be mounted perfectly

• the bimetal strip is shortened

• the bimetal strip is lengthened

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

• snap-disc

• pneumatic control

• thermistor

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

• snap-disc

• bimetal coil

• control bulb

• diaphragm

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

• bellows

• diaphragm

• Bourbon tube

• thermocouple

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

• thermocouple

• thermometer

• thermistor

• thermopile

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

• True

• False