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Figure 8-16.Pressure gauge snubber.
Pressurized Reservoirs

Fluid Power - Intro to Hydraulics, Pneumatics, and how it all works
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CHAPTER 9 RESERVOIRS, STRAINERS, FILTERS, AND   ACCUMULATORS Fluid  power  systems  must  have  a  sufficient and  continuous  supply  of  uncontaminated  fluid to operate efficiently. As stated in chapter 3 and emphasized  throughout  this  manual,  the  fluid must  be  kept  free  of  all  foreign  matter. This  chapter  covers  hydraulic  reservoirs, various  types  of  strainers  and  filters,  and accumulators  installed  in  fluid  power  systems. RESERVOIRS A  hydraulic  system  must  have  a  reserve  of fluid in addition to that contained in the pumps, actuators,  pipes,  and  other  components  of  the system. This reserve fluid must be readily available to  make  up  losses  of  fluid  from  the  system,  to make  up  for  compression  of  the  fluid  under pressure,  and  to  compensate  for  the  loss  of volume  as  the  fluid  cools.  This  extra  fluid  is contained in a tank usually called a reservoir. A reservoir  may  sometimes  be  referred  to  as  a  sump tank,  service  tank,  operating  tank,  supply  tank, or  base  tank. In  addition  to  providing  storage  for  the  reserve fluid needed for the system, the reservoir acts as a radiator for dissipating heat from the fluid and as  a  settling  tank  where  heavy  particles  of contamination  may  settle  out  of  the  fluid  and remain harmlessly on the bottom until removed by cleaning or flushing of the reservoir. Also, the reservoir  allows  entrained  air  to  separate  from  the fluid. Most  reservoirs  have  a  capped  opening  for filling,  an  air  vent,  an  oil  level  indicator  or  dip stick,  a  return  line  connection,  a  pump  inlet  or suction  line  connection,  a  drain  line  connection, and  a  drain  plug  (fig.  9-1).  The  inside  of  the reservoir  generally  will  have  baffles  to  prevent excessive  sloshing  of  the  fluid  and  to  put  a partition  between  the  fluid  return  line  and  the pump  suction  or  inlet  line.  The  partition  forces the  returning  fluid  to  travel  farther  around  the tank  before  being  drawn  back  into  the  active Figure 9-1.—Nonpressurized reservoir (ground or ship installation). system through the pump inlet line. This aids in settling the contamination and separating the air from  the  fluid. Large  reservoirs  are  desirable  for  cooling.  A large  reservoir  also  reduces  recirculation  which helps  settle  contamination  and  separate  air.  As a ‘‘thumb rule,” the ideal reservoir should be two to  three  times  the  pump  output  per  minute. However, due to space limitations in mobile and aerospace systems, the benefits of a large reservoir may have to be sacrificed. But, they must be large enough to accommodate thermal expansion of the fluid  and  changes  in  fluid  level  due  to  system operation. Reservoirs are of two general types— nonpressurized  and  pressurized. NONPRESSURIZED RESERVOIRS Hydraulic   systems   designed   to   operate equipment  at  or  near  sea  level  are  normally equipped  with  nonpressurized  reservoirs.  This includes  the  hydraulic  systems  of  ground  and  ship 9-1







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