Nate air balance
Fans are classified according to____. - ✔✔ correct answer THE DIRECTION OF THE AIR FLOW THROUGH
THE IMPELER
In an axial fan, air flow is ________ to the shaft of the impeller. In centrifugal fan, air flow
is___________to the shaft. - ✔✔ correct answer PARALEL, PERPENDICULAR
Name the three main types of axial fans___________________________ - ✔✔ correct answer
PROPELLER, TUBEAXIAL, VANEAXIAL
Name three common categories of centrifugal fans , based on impeller designs._____________. - ✔✔
correct answer RADIAL, BACKWARD CURVE, FORWARD CURVED
Are centrifugal fans with backward-curved blades more or less efficient than those with forwarded-
curved blades? __ - ✔✔ correct answer More
A graph that plots a fan's volume flow rate against static pressure is known as? - ✔✔ correct answer
PERFORMANCE CURVE
Does a system characteristics curve change if you install a different fan in the system - ✔✔ correct
answer No
The point at which a system characteristic curve and a fan performance curve intersect is called - ✔✔
correct answer POINT OF OPERATION
For stable operation, the system curve at a point that falls between the _______ and_______. - ✔✔
correct answer PREASURE PEAK, FREE DELIVERY
A system characteristic curve always takes the form of a(n) - ✔✔ correct answer PARABOLA
The greater the system resistance, the_________the system curve will be. - ✔✔ correct answer STEPPER
, Nate air balance
Name at least four of the variables that the fan laws use to predict fan performance - ✔✔ correct answer
FAN SPEED,AIR FLOW,,STATIC PRESSURE,, AIR DENSITY
According to the fan laws. how will the volume flow rate change if the speed of a fan is increased 15%.__
- ✔✔ correct answer THE CFM ALSO WILL INCREASE 15%.
An air distribution system is operating with a static pressure of 0.5 in.w.g and an air flow of 5,000 cfm. If
the air flow is increased to 6,500 cfm with with no other change, what is the new static pressure?
_____________ - ✔✔ correct answer 0.845-IN. W.G
The efficiency of a fan is defined as it is _________ divided by its________________. - ✔✔ correct
answer POWER OUTPUT, POWER INPUT
How does the installation of an add-on cooling coil affect air distribution in an existing warm air heating
system? - ✔✔ correct answer IT INCREASE THE SYSTEM RESISTANCE.
What adjustments must be made in order to maintain the same CFM that was delivered by the-furnace
before the installation of the add-on coil? - ✔✔ correct answer A HIGHER FAN SPEED WILL BE
NECESSARY
TO MAINTAIN THE SAME CFM.
In an Add-on cooling application, air flow generally must be_______________ for air conditioning proper
ration. - ✔✔ correct answer INCREASED
How can we calculate the existing CFM in a warm-air heating system? - ✔✔ correct answer -DIVIDE THE
NAMEPLATE OUTPUT OF THE
FURNACE (in BTUH) BY THE PRODUCT OF
1.1 TIMES THE AIR TEMPERATURE RISE
THROUGH THE FURNACE (in Farenheith)
What type of fan drive arrangement is normally used for forward-curved centrifugal fans with wheel
diameter of 7 in. or less? - ✔✔ correct answer DIRECT DRIVE
Fans are classified according to____. - ✔✔ correct answer THE DIRECTION OF THE AIR FLOW THROUGH
THE IMPELER
In an axial fan, air flow is ________ to the shaft of the impeller. In centrifugal fan, air flow
is___________to the shaft. - ✔✔ correct answer PARALEL, PERPENDICULAR
Name the three main types of axial fans___________________________ - ✔✔ correct answer
PROPELLER, TUBEAXIAL, VANEAXIAL
Name three common categories of centrifugal fans , based on impeller designs._____________. - ✔✔
correct answer RADIAL, BACKWARD CURVE, FORWARD CURVED
Are centrifugal fans with backward-curved blades more or less efficient than those with forwarded-
curved blades? __ - ✔✔ correct answer More
A graph that plots a fan's volume flow rate against static pressure is known as? - ✔✔ correct answer
PERFORMANCE CURVE
Does a system characteristics curve change if you install a different fan in the system - ✔✔ correct
answer No
The point at which a system characteristic curve and a fan performance curve intersect is called - ✔✔
correct answer POINT OF OPERATION
For stable operation, the system curve at a point that falls between the _______ and_______. - ✔✔
correct answer PREASURE PEAK, FREE DELIVERY
A system characteristic curve always takes the form of a(n) - ✔✔ correct answer PARABOLA
The greater the system resistance, the_________the system curve will be. - ✔✔ correct answer STEPPER
, Nate air balance
Name at least four of the variables that the fan laws use to predict fan performance - ✔✔ correct answer
FAN SPEED,AIR FLOW,,STATIC PRESSURE,, AIR DENSITY
According to the fan laws. how will the volume flow rate change if the speed of a fan is increased 15%.__
- ✔✔ correct answer THE CFM ALSO WILL INCREASE 15%.
An air distribution system is operating with a static pressure of 0.5 in.w.g and an air flow of 5,000 cfm. If
the air flow is increased to 6,500 cfm with with no other change, what is the new static pressure?
_____________ - ✔✔ correct answer 0.845-IN. W.G
The efficiency of a fan is defined as it is _________ divided by its________________. - ✔✔ correct
answer POWER OUTPUT, POWER INPUT
How does the installation of an add-on cooling coil affect air distribution in an existing warm air heating
system? - ✔✔ correct answer IT INCREASE THE SYSTEM RESISTANCE.
What adjustments must be made in order to maintain the same CFM that was delivered by the-furnace
before the installation of the add-on coil? - ✔✔ correct answer A HIGHER FAN SPEED WILL BE
NECESSARY
TO MAINTAIN THE SAME CFM.
In an Add-on cooling application, air flow generally must be_______________ for air conditioning proper
ration. - ✔✔ correct answer INCREASED
How can we calculate the existing CFM in a warm-air heating system? - ✔✔ correct answer -DIVIDE THE
NAMEPLATE OUTPUT OF THE
FURNACE (in BTUH) BY THE PRODUCT OF
1.1 TIMES THE AIR TEMPERATURE RISE
THROUGH THE FURNACE (in Farenheith)
What type of fan drive arrangement is normally used for forward-curved centrifugal fans with wheel
diameter of 7 in. or less? - ✔✔ correct answer DIRECT DRIVE
