Spencer 4BOB Multistage Centrifugal Blowers - Manual (Page 8)

88
SSuurrggee
CCAAUUTTIIO ONN:: DDoo nnoott ooppeerraattee bblloowweerr iinn ssuurrggee ((uunnssttaabbllee llooww
ffllooww rraannggee)).. DDaam maaggee ttoo bblloowweerr ccaauusseedd bbyy ooppeerraattiinngg iinn
ssuurrggee iiss nnoott ccoovveerreedd bbyy SSppeenncceerr wwaarrrraannttyy..
A blower in surge produces a rush or pulsating rhythmic air
sound caused when airflow into or out of the blower is restricted.
In addition to its characteristic noise, surge may be detected by
power or pressure fluctuations. Surge is destructive because it
is accompanied by excessive temperatures and aerodynamic
forces that will ultimately cause mechanical failure. A surge condi-
tion is simply eliminated by increasing the airflow either into the
system or to a bypass or vent. Various surge control devices
are also available from Spencer—see page 5.
NOTE: If a blower surges violently at startup, avoid recurrences
by leaving the throttling valve open at or near its normal operating
position.
NNoorrm maall O Oppeerraattiinngg LLiim miittss
NOTE: Use of a Spencer bearing temperature monitor and
vibration monitor is recommended to alert personnel to blower
operation outside the following limits.
• Vibration should not exceed 1.5 mils @ 3500 rpm, 1.8 mils @
2900 rpm or 3.0 mils @ 1750 rpm at each bearing housing.
All of these speeds have a velocity limit of 0.275 in/sec.
• Follow the motor manufacturerʼs recommendations for maxi-
mum motor bearing and winding temperatures.
• Blower bearing temperatures should not exceed the following
values at the bearing housing surface.
SSeerriieess IInnlleett EEnndd DDiisscchhaarrggee EEnndd
°°FF ((°°CC)) °°FF ((°°CC))
4BOH 150 (66) 150 (66)
4BOB 165 (74) 150 (66)
If abnormal operation is detected, shut the blower down and
refer to the Troubleshooting Guide in the back of this manual or
contact Spencer.
PPeerriiooddiicc O Oppeerraattiioonn
CCAAUUTTIIO ONN:: AAllll bblloowweerrss sshhoouulldd bbee ooppeerraatteedd ppeerriiooddiiccaallllyy..
In multiple blower installations, periodically rotate each blower
from standby to operating status.
PPaarraalllleell IInnssttaallllaattiioonn
CCAAUUTTIIO ONN:: AA cchheecckk vvaallvvee m muusstt bbee iinnssttaalllleedd iinn tthhee ddiisscchhaarrggee
lliinnee ooff eeaacchh bblloowweerr oorr iinnlleett ooff eeaacchh vvaaccuuuum m pprroodduucceerr ooppeerr--
aattiinngg iinn ppaarraalllleell ttoo pprreevveenntt rreevveerrssee ffllooww tthhrroouugghh iiddllee uunniittss..
CCAAUUTTIIO
ONN:: DDoo nnoott ooppeerraattee cceennttrriiffuuggaall bblloowweerrss iinn ppaarraalllleell
wwiitthh ppoossiittiivvee ddiissppllaacceem meenntt bblloowweerrss.. SSuucchh ooppeerraattiioonn m maayy
ddaam maaggee tthhee cceennttrriiffuuggaall bblloowweerrss aanndd wwiillll vvooiidd tthhee wwaarrrraannttyy..
When operating two or more blowers in parallel (typically identical
blowers), each must carry its share of the load. The current
readings of all motors should be approximately the same. It
may be necessary to adjust the individual throttling valve stops
to attain similar readings.
VVIIII.. LLuubbrriiccaattiioonn
W WAARRNNIINNG G:: DDIISSCCO ONNNNEECCTT AANNDD LLO OCCKK O OUUTT EELLEECCTTRRIICCAALL
PPO OW WEERR BBEEFFO ORREE PPEERRFFO ORRM MIINNG G LLUUBBRRIICCAATTIIO ONN..
M Moottoorr BBeeaarriinnggss
Follow the motor manufacturerʼs recommendations. Some
motors are equipped with sealed bearings not intended for
relubrication; these motors have no grease or drain plugs.
BBlloowweerr BBeeaarriinnggss ((44BBO OHH && 44BBO OBB))
4BOH and 4BOB blowers are equipped with deep-groove ball
bearings designed to carry the thrust and radial loads. These
bearings are packed at the factory with sufficient grease for
1500 to 8000 hours of continuous operation prior to relubrication.
Lubrication prior to blower operation is not recommended and
should not be attempted.
If, however, the blower has been stored for three months or longer,
remove the bearing caps and check for moisture or hard grease.
Discard any hard or dry grease and relubricate if necessary.
An average lubrication interval should be established based on
existing conditions. Several factors affect the frequency of
lubrication:
1. Operating temperature of the bearing
2. Indoor or outdoor blower location
3. Clean or dusty conditions
4. Ambient temperature
5. Predicted duty cycle
6. Bearing size and speed
Under actual operating conditions, the ideal lubrication interval
of 8000 hours should be adjusted according to the following
table.
NOTE: The higher limit of each range shown is for small bearings
(#308 and smaller); the lower limit is for large sizes. This table
is only a guide. An extremely dirty atmosphere could decrease
the lubrication interval as much as 50%.
O Oppeerraattiinngg CCoonnddiittiioonn LLuubbrriiccaattiioonn IInntteerrvvaal
I 1. 120—150°F bearing temp. 4000—6000 hours
2. Indoor installation
3. Clean atmosphere
4. 40—100°F ambient temp.
5. Continuous operation
II Same conditions as I except 6000—8000 hours
intermittent operation
Ill 1. 120—155°F bearing temp. 3000—5000 hours
2. Outdoor installation
3. All atmospheres
4. 0—104°F ambient temp.
5. Continuous operation
IV Same conditions as Ill except 5000—7000 hours
intermittent operation