Howden Roots RAS Whispair, Installation, Operation & Maintenance Manual

Page: 7 / 33

ILRB-3000 GEA20261
RAS and RAS-J WHISPAIR Blowers
Page 7 of 33
general discussion that is intended to be supported by
information from the Compressed Air and Gas Handbook
referenced earlier. To ensure satisfactory equipment
operation, the concrete foundation must be rigid, have
minimal defects, and should not be resonant in the
frequencies of the operating speed range of the equipment.
The foundation’s length and width must provide at least
6 inches (150 mm) from any edge to the nearest
machine anchor bolt (based on the location indicated in
the certified manufacturer’s general arrangement
drawing). The depth dimension should be determined by
design, with a minimum practical depth considered to be
twice the distance between the shaft centres (or gear
diameter) of the unit, or sufficient depth to attain a
concrete mass a minimum of one-and-a half times the
weight of the blower and motor.
The concrete block needs to cure for a minimum of 28
days before the blower is grouted in place. Any block
distortions during curing will have little or no effect on
equipment and alignment. To simplify machine levelling
and provide a good grouting bond, the top of the
foundation should be struck off as level as possible, but
left with a rough surface.
We do not recommend spring-type vibration isolating
mounting for use directly between the operating
equipment and the foundation. When such mountings
are required, they should be designed to carry a
reinforced concrete slab on which the equipment is
mounted. The slab must offer good rigidity against
bending and twisting. The suspension system requires
careful adjustment to produce a reasonably level
condition during operation. All piping requires flexible
sections and supports to reduce connection strains on
the unit.
We also do not recommend the direct use of structural
framing members for mounting the blower base to a
building structure. If this is unavoidable, it should be
restricted to smaller frame size units, and spring-type
mountings should not be used. Structural members
must be rigid, and will probably require reinforcement if
they are part of a building. Noise transmission can be
reduced by using a cork isolation pad to reduce the
transfer of vibration from the blower base to the building
structure. The pad should be 1 to 2 inches (25-50 mm)
thick, bedding on a full steel plate attached to the
structure and carrying the rigid concrete slab on which
the equipment is mounted.
Anchor Bolts and Plates - Place anchor bolts within
the foundation forms before the concrete is poured.
(See Table 2 for the recommended bolt sizes and
Figure 3 for proper bolt installation.) The bolts must be
located as accurately as possible based on the
dimensions provided on the certified installation
drawing. To obtain a bolt location tolerance of 1/8-inch
(3mm), use drilled templates firmly secured to the
foundation forms.
It is important to keep the bolt sleeves centered around
the bolts and free of concrete to allow the bolts to be
sprung enough to correct for small variations in bolt
setting and machine drilling. The sleeves are filled in the
final grouting operation. Adjust the bolt positions
vertically so that the top ends extend at least one-and-a-
half diameters above the soleplate or taper washer, or
as shown on the installation drawing.
Use the provided jack screws for easier height
adjustment levelling. Place steel plates, approximately
4” x 4” x 1/2” (100 x 100 x 13 mm, on the foundation
under each jack screw location. Plates and anchor bolts
are not furnished as standard accessories.
ILRB-3000 GEA20261 RAS and RAS-J WHISPAIR Blowers.pdf 7 03/09/2015 13:21:26