Howden Roots RAS Whispair, Installation, Operation & Maintenance Manual

Page: 8 / 33

ILRB-3000 GEA20261
RAS and RAS-J WHISPAIR Blowers
Page 8 of 33
Levelling
Because the unit should be as level as possible in all
directions, we recommend performing this critical step
using a
good quality machinist’s level with a ground glass
bubble vial. Level the blower from the drive shaft and pipe
flanges.
Machined baseplates have pads running along both the
length and width. On soleplates, the machined top surfaces
are used for levelling. Scrape the pads or surfaces clean,
and use a flat file to remove burrs on the high points.
When the blower and driver are factory mounted on a
common baseplate, treat the assembly as a unit for
levelling purposes. Use the jack screws to establish the
grouting space under the base flanges and to level the
base. Adjust the screws until the indicated variation from
the level does not exceed .001 inch per foot (.08 mm per
meter) in either length or width. To reduce twist, any
variations should all be in the same direction. The
maximum allowable twist is .001 inches per horizontal foot
(.08 mm per horizontal meter) measured between any two
sections of the base.
Units that are mounted on soleplates can be levelled in a
similar manner. The plates should be large enough to
provide extensions for levelling in both length and width on
the finished upper surfaces. Solidly fasten the plates to the
blower feet, which are machined flat and parallel to each
other. Then install and level the blower carefully, using jack
screws, shims, or wedges for adjusting. It is very important
to eliminate twist. Minor adjustments can be made by
placing shims directly under the blower feet. When a
satisfactory level condition is obtained, turn the anchor bolt
nuts down snug, but not tight.
Aligning
When the blower unit and its driver are direct coupled,
careful attention is required to align the drive shafts.
Precise alignment helps ensure satisfactory coupling
operation, as well as significantly reducing the chance of
damage to either the driving or driven unit from vibration or
thrust forces.
For package units with the driver and blower mounted in a
common baseplate, the two shafts have been placed in
approximate alignment at the factory. Because baseplate
deflections can occur during shipping and installation, it is
important to obtain a close coupling alignment during
levelling to ensure that only small final adjustments will
need to be made after grouting.
For soleplate applications, the separately mounted driver
must be positioned, levelled, and aligned during
installation. Whether the unit is on soleplates or its own
base, place shims (1/16 to 1/8 inch (2-3 mm) thick) directly
under the driver feet before setting the unit in place to
achieve more accurate final alignment. Establish spacing
between the two shaft ends as required by the coupling. If
a motor is being used that has end play in the shaft, be
sure its rotor is located on magnetic center before setting
this spacing. It also needs a limited end fl oat kit.
When the blower is driven through V-belts, the driver must
be mounted on an adjustable base to permit tightening or
removing of the belts. In this case, the driver shaft height is
of no concern, but it must be parallel to the blower shaft
and level. To position the driver properly, mount both
sheaves on their shafts (the shaft center distance must be
known).
Install the narrow hub type of blower sheave (usually the
one with a larger diameter) so that its inner hub face is not
more than 1/4 inch (6 mm) away from the bearing housing
end cover. The driver sheave should also be mounted as
close to its bearing as possible. Position the driver so that
the faces of the two sheaves are accurately in line, with the
adjustable base located so that two-thirds of its total
available movement is in the direction away from the
blower.
This positioning provides minimum belt wear and slip, and
allows sufficient adjustment for installing and tightening the
belts. Do not install the belts until the grouting has set and
the anchor bolts are tightened.
Blowers to be driven by v-belts may be provided with an
extended drive shaft and an additional outer bearing to
handle the side pull of the drive. Identified by the extended
housing for the outer bearing, these blowers can also be
driven by direct coupling to the motor if necessary.
Note: Blowers intended specifically for direct coupling
have no outer bearing, and can be seriously damaged if
used for belt drive applications. Consult your Howden
Roots sales office before belting these units.
Grouting
The final levelling step − and a preliminary alignment step −
involves grouting the foundation.
After proper curing, create a roughened top surface by
chipping away glazed areas and removing oil or grease
using a strong hot detergent or caustic solution.
Grouting compensates for surface irregularities in the
foundation and machine base and also helps restrain
shifting. Because anchor bolts are used for hold-down only,
the grout under the soleplate or base flange must be
adequately thick, it must flow into the anchor bolt sleeves
and all interior cavities, and it must be a variety that offers
minimal shrinkage during the setting period. Due to the
open frame design, the bedplate should be filled with
concrete that is level with the top of the main channels.
Special grouting materials designed to counteract
shrinkage are commercially available and are often
preferred to cement. Follow the manufacturer’s instructions
ILRB-3000 GEA20261 RAS and RAS-J WHISPAIR Blowers.pdf 8 03/09/2015 13:21:26