Aerovent IM-160 - Manual (Page 3)

3 Aerovent IM-160
Figure 1.
5
4
3
Tool AS-14093
Blade Tip
Cheater Bar
Hub Blade
Leading Edge
Detail "X"
Blade
Trailing Edge
Detail “X”
Vernier Index Line
(Blade As Shown
Is Adjusted To 35°
)
25.0"
5.0"
2.5"
5
4
3
Blade
Hub
Type J - Adjustable Pitch Wheel
Blade Angle Adjustment
The blades are set at the factory to the blade angle
that gives the performance specified on the order.
This angle should be checked prior to start-up. The
patented wheel construction uses friction and cen-
trifugal force to hold the blades in place. No disas-
sembly of the wheel is required to change the blade
angles. If it is necessary to change the blade angle,
the following procedure should be used:
1. Work safely. Make sure that proper safety precau-
tions have been followed. Electrical power must be
locked off.
2. The adjustment can be made through the inlet on
open inlet fans. On fans with ducted inlets, open
the wheel area access door.
3. Place adjustment tool around end of blade (see
Figure 6, below). If necessary, apply “cheater bar”
around the 1 1 ⁄
4
" diameter end for additional leverage.
The blades can be turned by hand on open
inlet fans. If additional leverage is needed, place
a wrench on the leading edge of the blade near
the hub. Take care not to mar the surface of the
blade.
4. Prior to adjusting the blade angle, check the per-
formance data to insure that the motor will not
overload.
5. Turn blade to desired angle. See Figure 1. There
is an indicator mark on the hub. Align the Vernier
index line on the blade with the indicator mark on
the hub. The Vernier has the characters 3, 4, and
5 with gradation lines in between. (Note: Character
3 is 30°, 4 is 40°, 5 is 50°.) Each gradation is 2.5°.
The blade is adjustable between 25° and 50°.
6. Friction and centrifugal force will hold the blade at
the set angle. No additional adjustment is necessary.
7. Adjust all blades to the same angle.
8. Close the wheel area access door before operating
the fan.
The propeller in an axial flow fan must be kept
reasonably clean if it is to perform properly. Fans
handling fresh air for ventilating purposes will seldom
need cleaning. Fans exhausting process air should
be cleaned as required. Dirt or chemical deposits will
usually build up evenly on a propeller and although
performance is affected, vibration is usually accept-
able until the deposits become thick enough to
break away in crust-like pieces. When this happens,
the propeller may be thrown out of balance and the
resulting vibration could be serious. Accumulations
should be removed by solvent cleaning or scraping.
If the propeller has been coated, be careful not to
cut through this protective covering.
The vaneaxial fan is constructed with a set of
guide vanes adjacent to the propeller. These should
be cleaned at the same time the propeller is cleaned.
The guide vanes are important to the performance
of the fan and should be inspected carefully. They
may accumulate dirt even under conditions where the
propeller remains clean.
Cleaning Propeller and Guide Vanes
The key to good fan maintenance is a regular and
systematic inspection of all fan parts. Severity of the
application should determine frequency of inspection.
The components requiring service are generally the
moving parts which include bearings, propeller, belts
and sheaves and motor. Included with this shipment
is a General Installation and Maintenance Manual (IM-
100) covering these items.
General Maintenance