21
For your nearest Roots office contact information, please consult the last page of this document.
temporary protective screen as described under
INSTALLATION is strongly recommended.
J
Recheck blower leveling, drive alignment and
tightness of all mounting bolts if installation is not
recent. If belt drive is used, adjust belt tension
correctly.
J
Turn drive shaft by hand to make sure impellers
still rotate without bumping or rubbing at any point.
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Ensure oil levels in the main oil sumps are correct.
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Check lubrication of driver. If it is an electric motor,
be sure that power is available and that electrical
overload devices are installed and workable.
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Close the three drain line valves in the bottom of
cylinder (VERTICAL BLOWER ONLY).
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Open the manual unloading valve in the discharge
air line. If a valve is in the inlet piping, be sure it is open.
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Bump blower a few revolutions with driver to check
that direction of rotation agrees with arrow near
blower shaft, and that both coast freely to a stop. Do
not restart the blower until it has come to a complete
stop.
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Turn on sealing water supply by opening the manual
shut-off valve (C in Figure 3f). Water will not flow to the
spray nozzle yet since solenoid operated valve (SV) is
electrically held closed until de-energized by the motor
starter.
J
Set valving at the water flow meter (Figure 3) so meter
is in the line, with the by-pass pipe loop closed. Set
spray control valve (b) about 1/4 open as a preliminary
adjustment. In a two-stage installation, also set corre-
sponding valve (A) at the second blower in the same
manner.
With the preceding checks and adjustment completed satis-
factorily, the vacuum blower should be ready for an operat-
ing tests. The following procedure is recommended:
A. Start the blower, let it accelerate to full speed, then shut
off. listen for knocking sounds, both with power on and
as the unit slows down. Also observe the sealing water
flow meter. A flow indication verifies that solenoid valve
(SV) has opened properly.
B. If no problems have appeared, restart the blower and let
it operate for 5 to 10 minutes under no-load conditions.
Adjust spray control valve (B) so that the water flow
meter show a rate in gallons per minute equal to the
Recommended Rate in Table 1d in this section. For a
two-stage installation, close valve (B) on first stage and
adjust valve (A) on second stage so that flow meter indi-
cates one-third of the allowable total flow rate. Then
open valve (B) until flow meter reads the correct total
water rate. This adjustment is semi-permanent, and the
two control valves should be locked by removing their
wheels or by other suitable methods. Valve (C) then
serves as the master valve.
C. Also during this period, check the cylinder and head-
plates for hot spots indicating impeller rubs. Continue to
be alert to unusual noises and changes in vibration.
Check oil levels in the sight windows at both sumps, and
verify several times theat the flow rate at the sealing
water meter remains reasonably constant.Shut unit down
and note whether water meter shows no flow, indicating
the solenoid water valve (SV) has closed properly. Open
valves in cylinder drain lines (vertical blower only) and
make sure lines are not clogged. Close valves after drain-
ing. Recheck all surface for hot spots.
D. If all conditions are acceptable, restart the vacuum blow-
er and observe operation for at least one hour. During
this period the normal vacuum working load should be
applied on the blower inlet gradually. As this is done, it is
important to make sure the inlet vacuum level and the
temperature rise do not exceed the allowable figures list-
ed in Table 1d in this section. Mercury manometers
should be installed at the inlet and discharge of the blow-
er to check pressure conditions. On two-stage units they
should be installed for both blowers.
Operating temperatures under average conditions will be low
enough that sufficient check can be made by feeling the
cylinder. However, if the cylinder temperature runs uncom-
fortably hot, it may be adisable to install inlet and discharge
thermometers for more accurate information. As the run pro-
gresses, continue to check for noises and vibration changes,
observe il levels in the sight glass at each sump, and watch
the water flow rate. Also note the behavior of the discharge
silencer drain trap. If any troubles appear, refer to the TROU-
BLESHOOTING CHECKLIST, page 12, as well as the items at
the bottom of this page for suggested remedies.
The vacuum blower should now be ready for continuous duty
under full working load. During the first several days make
periodic checks to be sure that all conditions remain reason-
ably steady and within specified limits. These checks can be
especially important if the unit is part of a process system in
Trouble
Possible Cause
Remedy
Excessive power
Excessive power
Vibration
Excessive water flow
Pressure unbalance (2-stage pump)
Water build-up in cylinder at start
Compare flow meter rate with table 1a, determine whether
water process has increased
Check interstage valve and piping for leakage
Clean out cylinder drainline and make sure outlet end is not
submerged
Additional Troubleshooting for VJ Blowers
