Page 175 - Practical Machinery Management for Process Plants Major Process Equipment Maintenance and Repair

Positive Displacement and Dynamic Blowers 157

To prevent these problems, one manufacturer, for instance, offers a
turning gear option that attaches to the outboard end of the fan shaft.
When the main drive shuts down, the turning gear engages and slowly
rotates the wheel and shaft to distribute the heat evenly. When the unit is
restarted, the turning gear automatically disengages.

Assembly and Installation of Fans

This section provides general procedures for installation of heavy-duty
fans that are shipped disassembled. The procedure is specifically for a
double inlet fan with inlet boxes and sleeve bearings on pedestals and
soleplates. Installation of other fan types will vary somewhat. The as-
sembly drawing furnished with the equipment should be checked. To en-
sure safety during installation, be sure to use only qualified personnel
and proper equipment.

Parts ldentlfication
Before starting to erect the fan, familiarize yourself with all the parts.
Make use of the assembly drawing and read the installation manual. Each
part of the assembly is marked with a factory identification number. Or-
ders for multiple units also indicate a sequence number. For example,
two identical fans could be identified as A1 for unit number one, A2 for
unit number two, etc. Part must not be interchanged between fans.

Fan Shafts
Fan shafts assembled to the wheel at the factory but shipped separately
should be stamped with a fit number in the keyway. The factory identifi-
cation number should also be stamped on the end of the shaft.

Wheels
Wheels assembled to the fan shaft at the factory but shipped separately
are generally stamped with a fit number on the wheel hub above the key-
way. Double width fans have the keyways marked with the number one
and two corresponding to the fan shaft. The fan identification number
and fit numbers also are painted on the wheel flange except for unpainted
or special material wheels which are usually tagged.

Housing and Boxes
The mating parts of all housings and inlet box sections are match-
marked with the fan identification number, a section number indicated by