Mechanical Air Movement

Question 1

List two groups or classes of fans

Answer 1

Axial (propeller) fans
Centrifugal (radial) fans

Question 2

List three types of axial-flow fans

Answer 2

Propeller fans
Tubeaxial fans
Vaneaxial fans

Question 3

Can propeller fans handle large volumes of air

Answer 3

Yes, large volumes of air at a low static pressure

Question 4

Can you connect ductwork to a tubeaxial fan?

Answer 4

Yes because they are designed for ducted applications

Question 5

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

Answer 5

addition of guide vanes behind the wheel to improve efficiency by straightening the flow of air

Question 6

What is another name for a centrifugal fan ?

Answer 6

Squirrel cage type fan

Question 7

Provide the uses and application for a forward curved fan

Answer 7

Suitable for clean air heating, air conditions and ventilation applications

Question 8

Provide the uses and application for a radial blade fan

Answer 8

Self cleaning and suitable for material transport such as, wood chips and grain systems. Used for heavy duty dust loads

Question 9

What does CWBHD stand for

Answer 9

Clockwise Bottom Horizontal Discharge

Question 10

How is the fan motor location determined

Answer 10

By facing the drive side of the fan and designating the positions by letters W,X,Y ,Z

Question 11

Can the placement of fittings in relationship to the fan be critical

Answer 11

Yes, improper placement can result in excessive turbulence

Question 12

How much straight duct is required after a fitting to achieve 100% effective duct length, for systems with an air flow of 2500 fpm or less

Answer 12

You need 2.5 times the duct diameter to achieve 100% effective length

Question 13

What items would cause system resistance or pressure losses in an HVAC system

Answer 13

Pressure losses come from fittings, filters, coils, dampers etc.

Question 14

List five pieces of information that can be found on a fan performance chart

Answer 14

Model, Shaft diameter, Maximum BHP , CFM, Outlet Velocity

Question 15

What damper is installed in branch fittings

Answer 15

Splitter Damper

Question 16

When would air extractors be used

Answer 16

Where there is not an adequate amount of room to mount a splitter damper to efficiently direct the correct amount of air down the branch line or diffuser takeoff

Question 17

List three important functions of multi-blade dampers

Answer 17

To control and mix outside air with return air
To bypass heat transfer equipment
To control air quantities handled by the fan

Question 18

Name two styles of multi-blade dampers

Answer 18

Parallel Blade

Opposed Blade

Question 19

Describe fan total pressure

Answer 19

The sum total of a fan’s static pressure and its velocity pressures.

Question 20

What fan blade is suitable for use in restaurants and places where moisture and dust is present in the air

Answer 20

Backward inclined blade

Question 21

Which blade is the most quiet and efficient

Answer 21

Airfoil blade

Question 22

Which fan blade is designed for material handeling and heavy duty dust loads

Answer 22

Radial blade

Question 23

What type of fan is used to provide air curtains above doors

Answer 23

Cross flow fan

Question 24

Which is fan is the MOST effecient

Answer 24

Vaneaxial fan

Question 25

In which fan does air leave the impeller at right angles

Answer 25

Centrifugal fan

Question 26

What are the advantages of forward curve blades compared to backward inclined blades

Answer 26

Quiet and more efficient than backward inclined blades

Question 27

What class of fans are suitable for low volumes and pressures

Answer 27

Axial flow fans

Question 28

Propeller fans can be directly mounted to a wall T or F

Answer 28

True

Question 29

In what two ways do centrifugal fans produce pressure

Answer 29

Centrifugal force and Kinetic energy

Question 30

What do forward curve blades depend more on ?

Answer 30

Velocity pressure

Question 31

Forward curved blades are common in wheel diameters up to 24” T or f

Answer 31

True

Question 32

What type of fan is used where low sound levels are critical

Answer 32

Mixed flow fan

Question 33

How is rotation and discharge determined

Answer 33

Fan drive position

Question 34

Define system resistance curve

Answer 34

Sum of pressure losses in the system

Question 35

What type of damper is used in non- ducted applications

Answer 35

Nested inlet vane dampers

Question 36

Propeller disc fans are designed to have duct attached to them T or F

Answer 36

False

Question 37

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

Answer 37

Radial blades

Question 38

Which fan should never be used in a ductless system

Answer 38

Forward curved blade centrifugal fan

Question 39

What is the best fan to use on a blowpipe system for a sawmill

Answer 39

Radial blade centrifugal fan

Question 40

The most accurate volume control of air is obtained by using what kind of damper

Answer 40

Opposed blade

Question 41

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

Answer 41

1 1/2 times the width of the small duct

Question 42

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

Answer 42

Parallel blade damper