Blade Measurement and Adjustment Instructions

For Style “C”

Cast Aluminum Blade Propeller Fans
NOTE: Before attempting to measure or adjust the fan (b) Position one blade as suggested in step #3(a)
blades, make sure the unit is off and power has been and loosen U-bolts or blade retention clamps
disconnected. Carefully remove any fan until blade can be rotated to correct angle.
appurtenances to gain access to the blade assembly. Retighten bolts, carefully check pitch angle to
make sure of correct angle when blade is
1. USE OF BUBBLE-TYPE PROTRACTOR. secure. Use of a torque wrench for this purpose
American Coolair can provide a bubble-type is required. Torque should be set for a
protractor head for field use in checking and setting minimum of 16 ft. lbs. and a maximum of 18 ft.
the blade angle of adjustable pitch type fans. The lbs. for propeller with U-bolts. For propellers
protractor head is a 180° dial with a bubble. with blade retention clamps, torque blade clamp
nuts to 16-18 ft. lbs. Blade pitch angle on
2. POSITION OF FAN (OR BLADE ASSEMBLY). As successive blades can be set and secured in
the actual blade angle is a relationship to the plane the same fashion.
of the blade hub, it is necessary to check the hub
section in the horizontal or vertical plane. This can (c) Short cut to setting pitch on successive blades:
be done by setting the protractor head on either 0° After getting correct pitch angle on one blade,
or 90° and checking the angle of the hub section. use sharp pencil and carefully scribe blade tip
See figures on reverse side. position on surface of adjacent orifice ring. With
this reference mark other blades may be set to
3. MEASUREMENT OF BLADE PITCH. American this exact position without use of a protractor
Coolair blade angle settings are measured at the head.
extreme tip of the blade. To check the existing
blade angle on a propeller, the protractor head 5. CAUTION. Any change in blade pitch from
should be placed across the concave face of the factory setting will affect motor load. An
blade as near the tip of the blade as possible. As increase in blade pitch may result in motor
the blade angle changes approximately 1° per overload and possible trip-out or damage to the
linear inch of the blade, make whatever adjustment motor. Motor load should be carefully checked
is necessary for a measurement made an inch or after any adjustment in blade pitch to be sure it
more away from the blade tip. is within safe limits. It is recommended that you
contact your American Coolair representative
(a) MEASUREMENT OF BLADE ANGLE WITH before making any adjustments in blade
PROPELLER IN VERTICAL PLANE. Position pitch.
one blade so that it is in a horizontal position.
Place protractor head across concave face of
blade at tip and measure pitch angle from WARNING CAUTION
90°. Position successive blades at this same
spot and check each pitch angle. See figures DO NOT INSTALL FAN WITH MOVING PARTS WITHIN 8
FEET OF FLOOR OR GRADE LEVEL WITHOUT A GUARD
on reverse side. THAT COMPLIES WITH OSHA REGULATIONS. DO NOT
USE UNLESS ELECTRICAL WIRING COMPLIES WITH
ALL APPLICABLE CODES. DO NOT WIRE WITHOUT
PROVIDING FOR A POWER SOURCE DISCONNECT AT
(b) MEASUREMENT OF BLADE ANGLE WITH THE FAN ITSELF. DO NOT SERVICE EXCEPT BY A
QUALIFIED MAINTENANCE TECHNICIAN AND ONLY
PROPELLER IN HORIZONTAL PLANE. AFTER DISCONNECTING THE POWER SOURCE.
FAILURE TO OBSERVE THESE PRECAUTIONS CAN
Position protractor head across concave face RESULT IN SERIOUS INJURY OR DEATH.
of blade at tip and measure pitch angle from
0°. Check remaining blades in this same
fashion. See figures on reverse side.

4. SETTING BLADE PITCH WITH BUBBLE-TYPE

PROTRACTOR.

(a) Set correct angle on protractor head to

provide desired blade pitch using P.O. Box 2300 ~ Jacksonville, Florida 32203
measurement technique outlined above. Phone: (904) 389-3646
Fax: (904) 387-3449 or (904) 381-7560
E-mail: fans@coolair.com

Form No. 220-35-4 (September, 2004)

 Instructions for Vertically Instructions for Horizontally
Mounted Blade Assembly Mounted Blade Assembly
1. Set the protractor on the zero degree marks
2. Place the protractor flat on the hub face or hub bushing
perpendicular to the axis of a blade. If you are using a
digital protractor with an “Alt-0” function, set this position
as the Alternate 0°. Otherwise, turn the blade assembly
around slowly until the turret indicates a balance point.
See Figure 5.

Hub

Figure 1

1. Place the protractor flat against the hub face or hub

bushing as shown in Figure 1.
2. Turn the revolving turret until it indicates a balance point.
See Figure 2. If you are using a digital protractor with an
“Alt-0” function, set this position as the Alternate 0°, then
place the protractor as described in step #4 to measure Figure 5
the blade angle.

Figure 2 3. Once the zero point is determined, move the protractor

along the blade directly across from the zero point
position to the tip of the blade. Mark this point on the
3. Turn the protractor around to read the angle as shown in orifice of the fan. See Figures 5 & 6. Making sure each
Figure 3. Start from either zero point. blade is aligned with this mark, take the pitch reading by
placing the protractor flat against the blade tip as shown in
Figure 4.

Protractor
Figure 3

4. Place the protractor flat against the blade tip (as shown in
Figure 4) and turn the turret until it indicates a balance
point as in steps #1 & #2 above.

Blade

Figure 4 Figure 6

5. Proceed as in step #3, reading from the same zero point.

6. Subtract the smaller reading from the larger reading. NOTE: The turret bubble should face left for both readings.
Example: Reading in step #3 = 125°
Reading in step #5 = 140°
Blade pitch = 140° - 125° = 15°