Mechanical Air Movement And Control Flashcards

1
Q

What are two groups or classes of fans ?

A

Axial (propeller)
Centrifugal (radial)

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2
Q

What are three types of axial flow fans ?

A

Propeller
Tubeaxial
Vaneaxial

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3
Q

Can propeller fans handle larger volumes of air ?

A

Yes at low static pressure

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4
Q

Can you connect ductwork to a tube axial disc fan ? If yes explain

A

Yes but the air is discharged in a spiral motion producing high losses in the duct system

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5
Q

What is cubic feet per minute ?

A

Measure of volume of air moved by fan per minute

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6
Q

What are the two general groups of fans

A

Axial (propeller)
Centrifugal (radial)

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7
Q

What are four types of fan blades

A

Forward curved
Backward inclined
Airfoil
Radial

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8
Q

What type of fan has low noise emmison and are suitable for resturants exhaust or wgere air contains moisture or dust ?

A

Backward inclined

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9
Q

How is the location of the motor of discharged determined ?

A

By facing the drive side

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10
Q

What is the difference between a tube axial fan and a vane axial fan ?

A

Vaneaxial has a guide vanes behind the wheel to improve efficiency by straightening the flow of air

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11
Q

What is another name for a centrifugal fan ?

A

Squirrel cage

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12
Q

What are the uses and applications for a forward curved fan ?

A

Used for low pressure heating ventilating and air conditioning systems ranging from room air conditioners to residential furnaces

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13
Q

What are the uses and applications for a forward curved fan ?

A

Used for low pressure heating ventilating and air conditioning systems ranging from room air conditioners to residential furnaces

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14
Q

What are the uses and applications for a radial blade fan ?

A

For material handling high pressure industrial applications like saw dust

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15
Q

What does cwbhd stand for ?

A

Clock wise bottom horizontal

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16
Q

How is motor location determined ?

A

Facing drive side of the fan and designating the positions by letters w x y or z

17
Q

How much straight duct is required to achieve 100% effective duct length for systems with an airflow of 2500fpm or less ?

A

2.5 duct diameters

18
Q

What items would cause system resistance or pressure loss in an hvac system ?

A

Fittings coils dampers

19
Q

List 5 peices of info that can be found on a fan performance chart ?

A

Horse power
Volume
Static pressure
Rpm
System curves

20
Q

What damper is installed in branch fittings ?

A

Splitter dampers

21
Q

When would air extractors be used ?

A

When there is not adequate room to mount a splitter damper

22
Q

List 3 important functions of multi blade dampers ?

A

Control and mix outside air with return ,
Bypass heat transfer equitment ,control air qualities

23
Q

Name two styles of multi blade dampers ?

A

Parellel or opposed blade

24
Q

A 1000cfm of air is to be moved through a duct system with a total pressure of 0.4” wc which type of fan is best for this installations ?

A

Forward curved blade centrifugal fan

25
Q

Propeller disc fans are designed to ?

A

Have no duct at all

26
Q

The backward inclined airfoil fan is a refinement of the flat blades backward inclined centrifugal fan in what respect ?

A

It has better static efficiency
It is quieter

27
Q

What type of fan blade arrangement is ussally used in air pollution control applications with high particulate loadings ?

A

Radial blades

28
Q

Which fan should never be used in a ductless system ?

A

Forward curved blade centrifugal fan

29
Q

In most cases what is the best fan to use on a blow pipe system for a sawmill ?

A

Radial bladed centrifugal fan

30
Q

Most upflow residential heating equitment uses a centrifugal fan in what position configuration?

A

Ccwubd

31
Q

The most accurate volume control of air is obtained by using a ?

A

Opposed blade damper

32
Q

An accepted method of determining the length of a splitter damper is ?

A

1.5 times the width of the small duct

33
Q

Which damper is generally used in locations where it is either fully open or fully closed ?

A

Pareellel blade damper

34
Q

These fans provide right angle airflow in a rectangular shape and are useful in applications such as air curtains over doorways ?

A

Cross flow fans

35
Q

Inlet box dampers supplied with parallel blades offer performance characteristics similar to inlet vane dampers
(True or false )

A

True

36
Q

Parallel blade dampers are the best for modulating air flow ?

(True or false)

A

False
Either fully opened or fully closed

37
Q

Forward curved fans are common in wheel diameters up to ??

A

24”

38
Q

What type of fan has low noise emission and are suitable for restaurant exhaust systems or where air contains moisture or dust ?

A

Backward inclined blades