Unit 37: Air Distribution & Balance

If there's more than a _________ difference between the air inside & the air outside the duct, it should be insulated.

15°F

In a typical air-conditioning (cooling) system, _______ cfm of air is normally moved per ton of refrigeration.

400

An extended plenum system is a type of

duct system

Squirrel cage blowers are used in air-conditioning systems primarily in _______ applications.

ducted

Two types of fans are the propeller &...

forward curved centrifugal (aka squirrel cage or blower wheel)

The pressure in a duct system is measured in:

in. wc.

To measure airflow by traversing the duct is to

measure the velocity of the airflow in a pattern across a cross section of the duct & averaging the measurements.

One reason for friction loss in duct systems is the

rubbing action of air on the walls of the duct.

A common way to fasten sections of round galvanized steel duct to each other is by using

self-tapping sheet metal screws

A drive cleat is used when installing ________ duct systems.

sheet metal

The diffuser

spreads the air from the duct into the desired pattern.

we. of the following is typically measured with a manometer?

static pressure in a duct system

The fittings between the main truck & branch ducts in a duct system are called

takeoff fittings

Static pressure in a duct system is

the force per unit area in a duct.

Velocity pressure is the:

total pressure - the static pressure.