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SECTION III REGULATION
SECTION IV OPERATION

TM-5-3895-374-24-2 M081 Asphalt Mixing Plant Manual
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TM 5-3895-374-24-2 AUXILIARY VALVE ADJUSTMENT The auxiliary valve is mounted on the bare compressor.      The   valve   has   a   cut-out   and   a   differential adjustment.    The  cut-out  point  is  the  pressure  at  which  the valve  will  open  allowing  the  compressor  to  unload,  the  cut-in point is the pressure at which the valve will close allowing the compressor to reload, and the differential is the span between the cut-out and the cut-in points. Figure 3-3.Typical Auxiliary Valve adjustments. To   adjust   the   cut-out   pressure,   (See   Figure   3-3,) loosen the range locknut and turn the range adjustment screw clockwise  for  higher  pressure  and  counterclockwise  for  lower pressure.  Retighten the range locknut after adjusting the cut- out pressure. The  differential  pressure  will  vary  with  the  change  in cut-out pressure. The  differential  pressure  is  preset  at  approximately 15%  of  the  cut-out  pressure  and  should  not  be  re-adjusted unless  absolutely  necessary.    Small  differentials,  5  PSIG  or less,   tends   to   produce   internal   chattering   and   should   be avoided. To  adjust  the  differential  pressure,  (See  Figure  3-3), loosen   the   differential   locknut   and   turn   the   differential   nut clockwise for greater differential and counterclockwise for less differential. While adjusting the differential nut, the range locknut should be loosened and the range adjustment screw must be held from turning to avoid changing the cut-out pressure. Retighten  the  differential  locknut  and  the  range  locknut  after adjusting the differential pressure. INTERMITTENT DUTY FORMULA Model 7100 operating above 200 psig (14 kg/sq. cm)  are  to  be  operated   according   to   the   "Intermittent   Duty Formula." INTERMITTENT DUTY FORMULA Pump-up   time   should   not   ordinarily   exceed   thirty   (30) minutes   or   be   less   than   ten   (10)   minutes.      Shutdown periods  between  cycles  of  operation  should  be  at  least equal to the pump-up time.  Note:  When the  compressor is   regulated   by   constant   speed   control,   the   shut-down period is the time the compressor is operating unloaded. A   pump-up   time   limit   with   the   following   cool-down period   is   recommended   to   protect   the   valves   and   heads against stabilized high operating temperatures, which could rapidly build up carbon in these areas. All inquiries for high-pressure compressor application where   the   "use"   cycle   differs   from   the   "Intermittent   Duty Formula"   should   be   referred   to   the   nearest   Ingersoll-Rand branch office. page 3 - 835







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