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OPERATING CHARACTERISTICS
Figure 3-Blower Orientation and Lubrication Points.

TM-5-3895-374-24-2 M081 Asphalt Mixing Plant Manual
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TM 5-3895-374-24-2 Temperature rise then is the limiting condition.  In other words, the   operating   limit   is   always   determined   by   the   maximum rating reached first.  It can be any one of the three:  pressure, temperature or speed. Be sure to arrange connections or taps for thermometers and  mercury  type  pressure  or  vacuum  gauges  at  or  near  the inlet and discharge connections of the blowers.  These, along with   a   good   tachometer.      will   enable   periodic   checks   of operating conditions to be made easily. PRESSURE-On   pressure   service,   the   pressure   rise   in pounds   per   square   inch   (kPa)   (between   blower   inlet   and discharge)  must  not  exceed  the  figure  listed  for  the  specific blower frame size concerned.  Also, in any system  where  the blower  inlet  is  at  a  positive  pressure  above  atmosphere.    the discharge   pressure   must   never   exceed   25   PSI   (172   kPa) gauge regardless of blower size. On vacuum service, with the discharge going to atmospheric pressure, the inlet suction or vacuum in inches of mercury (Hg.) (kPa) must not be greater than the values listed for the specific frame size. TEMPERATURE-Various blower frame sizes are approved only for installations where the following temperature limitations can be maintained in service. A. Measured   temperature   rise   in   Fahrenheit   degrees   (Co) must not exceed listed values when the inlet is at ambient temperature.        Ambient    is    considered    as    the    general temperature of  the  space  around  the  blower.    This  is  not outdoor     temperature     unless     the     blower     is     installed outdoors. B. If   inlet   temperature   is   higher   than   ambient,   the   listed allowable temperature rise values must be reduced by 23 of    the    difference    between    the    actual    measured    inlet temperature and the ambient temperature. C. Average   of   inlet   plus   discharge   temperature   must   not exceed 220°F (104°C) SPEED    RANGE-UNIVERSAL    RAI®    blowers    may    be operated  at  speeds  up  to  the  maximums  listed  for  various frame sizes.  They may be direct coupled to suitable constant speed   drivers   if   pressure/temperature   conditions   are   also within limits.  At low speeds, excessive temperature rise may be the limiting factor as noted in the preceding example. Table 1-Maximum Allowable Operating Conditions. Inlet Vac. Temp.  Rise Press.  Rise Frame Speed Inches Hg. Fahr.  Deg. PSI Size RPM (kPa) (C) (kPa) 22 5275 14 (47) 225 (125) 12 ( 82) 24 5275 14 (47) 185 (102) 7 ( 47) 32 3600 14 (47) 225 (125) 15 (101) 33 3600 14 (47) 170 ( 94) 12 ( 82) 36 3600 14 (47) 115 ( 64) 7 ( 47) 42 3600 14 (47) 240 (133) 15 (101) 45 3600 14 (47) 170 ( 94) 10 ( 68) 47 3600 14 (40) 130 ( 72) 7 ( 47) 53 2850 14 (47) 195 (108) 15 (101) 56 2850 14 (47) 180 (100) 10 ( 68) 59 2850 14 (40) 115 ( 64) 7 ( 47) 65 2350 16 (53) 250 (139) 15 (101) 68 2350 16(53) 240 (133) 12 ( 82) 615 2350 12(40) 130 ( 72) 6( 40) 76 2050 16 153) 250 (139) 15 (101) 711 2050 16 ( 53) 210 (117) 10 ( 68) 718 2050 12 ( 14) 130 ( 72) 6 ( 40) BLOWER ORIENTATION The unique removable feet feature of Roots UNIVERSAL RAI"  blowers  permit  field  modification  of  blower  mounting  by repositioning  blower  feet  and  gear  box  breather  as  shown  in Fig.  3. Four blower mounting positions are possible: 1. Horizontal  mounting,  vertical  air  flow,  drive  shaft  on left. 2. Same as (1) except drive shaft on right. 3. Vertical  mounting,  horizontal  air  flow,  drive  shaft  on bottom. 4. Same as (3) except drive shaft on top. To change blower mounting: 1. Place blower on its feet. 2. Loosen feet capscrews (32). 3. Place blower on a solid base resting on the gear box end with drive shaft on top. 4. Remove feet.  (Note-Feet capscrews (32) are longer than  cylinder  capscrews  (26),  only  capscrews  (32) are to be used for feet.) 5. Remove cylinder capscrews (32) where feet are to be re-installed.    Install  capscrews  (26)  in  the  location previously occupied by feet capscrews (32). 6. Install feet using capscrews (32). 7. Place blower on its feet on flat surface. 8. Loosen  feet  capscrews  (32)  and  square  up  blower and re-tighten capscrews (32). 9. Gear box has four threaded holes, one with breather and  three  with  pipe  plugs.    Remove  pipe  plug  (21) from  the  top  most  hole.    Remove  breather  (25)  and install  it  in  the  top  most  hole.    Install  pipe  plug  that was    removed    from    the    top    hole    into    the    hole previously  occupied  by  the  breather.    The  breather and  the  pipe  plug  should  be  sealed  with  a  thread sealer. For  convenience.    the  position  of  the  grease  fitting (37) and the relief fitting 138) could be interchanged, however  each  bearing  must  have  one  grease  fitting 137) and one relief fitting (38). Figure 2-Breather Installation. page 3-802







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