CAMCORP Blower Package with Roots Blower - Manual (Page 28)

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ROOTS, RAM, URAI and WHISPAIR are trademarks of Dresser, Inc.
Dresser Design and Universal RAI are registered trademarks of Dresser, Inc.
The driver sheave should also be mounted as close to
its bearing as possible, and again should fit the shaft
correctly. Position the driver on its adjustable base so
that 2/3 of the total movement is available in the
direction away from the unit, and mount the assembly
so that the face of the sheave is accurately in line with
the unit sheave. This position minimizes belt wear, and
allows sufficient adjustment for both installing and
tightening the belts. After belts are installed, adjust
their tension in accordance with the manufacturer’s
instructions. However, only enough tension should be
applied to prevent slippage when the unit is operating
under load. Excessive tightening can lead to early
bearing failures or shaft breakage.
Before operating the drive under power to check initial
belt tension, first remove covers from the unit
connections. Make sure the interior is still clean, then
rotate the shaft by hand. Place a coarse screen over
the inlet connection to prevent anything being drawn
into the unit while it is operating, and avoid standing
in line with the discharge opening. Put oil in the sumps
per instructions under LUBRICATION.
Piping
Before connecting piping, remove any remaining
anti-rust compound from Unit connections. Clean pipe
should be no smaller than unit connections. In addition,
make sure it is free of scale, cuttings, weld beads, or
foreign material of any kind. To further guard against
damage to the unit, especially when an inlet filter is not
used, install a substantial screen of 16 mesh backed
with hardware cloth at or near the inlet connections.
Make provisions to clean this screen of collected
debris after a few hours of operation. It should be
removed when its usefulness has ended, as the wire
will eventually deteriorate and small pieces going into
the unit may cause serious damage.
Pipe flanges or male threads must meet the unit
connections accurately and squarely. DO NOT attempt
to correct misalignment by springing or cramping the
pipe. In most cases this will distort the unit casing and
cause impeller rubbing. In severe cases it can prevent
operation or result in a broken drive shaft. For similar
reasons, piping should be supported near the unit to
eliminate dead weight strains. Also, if pipe expansion is
likely to occur from temperature change, installation of
flexible connectors or expansion joints is advisable.
Figure 2 represents an installation with all accessory
items that might be required under various operating
conditions. Inlet piping should be completely free of
valves or other restrictions. When a shut-off valve can
not be avoided, make sure a full size vacuum relief is
installed nearest the unit inlet. This will protect against
unit overload caused by accidental closing of the
shut-off valve.
Need for an inlet silencer will depend on unit speed and
pressure, as well as sound-level requirements in the
general surroundings. An inlet filter is recommended,
especially in dusty or sandy locations. A discharge
silencer is also normally suggested, even though
Whispair units operate at generally lower noise levels
than conventional rotary blowers. Specific recommen-
dations on silencing can be obtained from ROOTS.
Discharge piping requires a pressure relief valve, and
should include a manual unloading valve to permit
starting the unit under no-load conditions. Reliable
pressure/vacuum gauges and good thermometers at
both inlet and discharge are recommended to allow
making the important checks on unit operating condi-
tions. The back-pressure regulator shown in Figure 2
is useful mainly when volume demands vary while the
unit operates at constant output. If demand is constant,
but somewhat lower than the unit output, excess may
be blown off through the manual unloading valve.
In multiple unit installations where two or more units
operate with a common header, use of check valves
is mandatory. These should be of a direct acting or free
swinging type, with one valve located in each line
between the unit and header. Properly installed, they
will protect against damage from reverse rotation
caused by air and material back-flow through an
idle unit.
After piping is completed, and before applying power,
rotate the drive shaft by hand again. If it does not move
with uniform freedom, look for uneven mounting, piping
strain, excessive belt tension or coupling misalignment.
DO NOT operate the unit at this time unless it has
been lubricated per instructions.