Howden Roots RAS Whispair, Installation, Operation & Maintenance Manual

Page: 9 / 33

ILRB-3000 GEA20261
RAS and RAS-J WHISPAIR Blowers
Page 9 of 33
when using these materials. Care must be exercised when employing non-shrink additives with cement, as too much
can be worse than none. Any gas-forming or air-entraining
additives should be avoided, because they tend to reduce
grout strength.
Wait at least 24 hours before tightening anchor bolts or
connecting piping. When jack screws have been used for
levelling, make sure the bottom of the levelling screw is
treated according to the grout manufacturer’s instructions
so that it can be backed off. Such points of concentrated
loading are likely to wear during machine operation,
resulting in loose anchor bolts. Final bolt tightening should
only be enough to hold the machine firmly against the
foundation and prevent vibration.
After all anchor bolts are secured, recheck the blower for
twist and level. Working from the finished pad on top of the
cylinder, make corrections to meet the requirements
specified under LEVELING by shimming under the blower
feet. Then rotate the drive shaft by hand to make sure both
impellers turn freely at all positions.
When the blower is directly coupled to its driver, final
alignment of the two shafts should be accomplished by
very carefully adjusting the shims under the driver feet.
While a flexible coupling can accept some degree of
misalignment, it should not be forced to compensate for
careless workmanship. The flexing or sliding member in a
coupling transmits undesirable forces between the two
shafts in proportion to the degree of misalignment, thus
promoting vibration and unnecessary wear problems.
The two basic types of misalignment − offset and angular −
often occur together. Use the following limits to achieve
satisfactory coupling operation: maximum deviation in
offset alignment not greater than .005 inches (.13 mm) total
indicator reading on the coupling hubs, and maximum
deviation from parallel of the inside coupling faces not
greater than .001 inches (.03 mm) when checked at six
points. When the driver is a steam turbine, the final
alignment should be made with the turbine at operating
temperature in order to allow for shaft movement resulting
from expansion.
Piping
Before connecting the piping, thoroughly clean it. The
piping should be sized so that air velocity in the line does
not exceed 100 feet per second (30 m per second). When
a blower is operated at or near its maximum volume rating,
the piping should be no smaller than the blower
connections.
Use long radius elbows whenever possible to ensure
smooth flow. Design the piping layout so that no strain is
placed on the blower, either from weight or expansion
forces. Provide adequate supports, anchors, and
expansion joints or loops.
We recommend installing a spool-type rubber expansion
joint near the blower inlet connection. In addition, a similar
unit with control elements added to minimize piping
vibrations may be required near the discharge. Depending
on the blower speed, operating pressure, length and type
of piping, and surrounding area sound level requirements,
the use of snubbers or silencers in
the inlet or discharge piping may be necessary. For specific
silencer recommendations, contact your nearest Howden
Roots sales office.
Typically, inlet piping should be free of valves or
restrictions, but when a shutoff valve cannot be avoided,
make sure a full-size vacuum relief valve is installed near
the blower inlet connection (see Figure 5). This will protect
against an overload caused by accidental valve closing.
Further protection can be provided by installing a
dependable pressure-sensitive device with an alarm or
shutdown action.
During initial operation, install a temporary corrosion-
resistant screen at the compressor inlet connection. The
screen should be made of 16 mesh (.020 inch diameter)
wire backed with 2 mesh wire cloth. The backing cloth-wire
diameter should be a minimum of:
• 0.063 inch diameter for 12-inch pipe
• 0.080 inch diameter for 16-inch pipe
ILRB-3000 GEA20261 RAS and RAS-J WHISPAIR Blowers.pdf 9 03/09/2015 13:21:26