Features of the gear pump

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All You Need To Know About Gear Pumps And Their
Types
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• A pump is equipment used to take fluid from one
  place to another from lower to higher position. 
• The gear pump is a type of hydraulic pump. It is
  used to develop high pressure and is also called
  a fixed displacement pump because it removes the
  limited quantity of fluid during the rotation of
  the shaft. PTO gear pumps are one of the best
  gear pumps, which are also known as Power
  take-offs gear pumps.
• Since gear pumps are positive displacement pumps,
  you cannot use them without safety devices. If a
  pump has two sides that are in and out, more
  pressure will be created in the side of out then
  it can lead to the burst of pump or rupture of
  the pump due to its constant working load. It is
  necessary to use a safety relief valve to not
  lead to any damage in the pump area.
• The first thing when we think about the gear
  pumps comes to our mind about the gears. The
  gears used can be of three types as Helical gear,
  Spur gear, and Herringbone gear. These are the
  different designs. The most expensive among gear
  pumps are PTO gear pumps.
• These gear pumps use two different gears. One is
  driven gear and driving gear. If it starts
  rotating, the pressure will be created at the
  pump's inlet, and it will get into the pump, and
  the fixed volume of liquid will be pressurized. 

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• The cavities between the teeth of the rotating
  gears so that particular fluid will be
  pressurized. Delivers from the outlet through the
  discharge pipe. Works on close tolerances. 
• To generate the higher pressure, if there are no
  tolerances between two gears, we won't generate
  the required pressure at the pump's outlet. So
  there is a need to maintain the closed tolerances
  between the gear pumps.
• Types of gear pumps
• ? External gear pump 
• ? Internal gear pump.

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External Gear Pumps and Their Working

• External gear pumps are frequently used in large
  industries. At the inlet of the external gear
  pump, which is continuously meshing with each
  other at the inlet side, they come out of the
  meshing, and the expanded volume gets created at
  the inlet side of the pump.
• Due to the expanded volume, the liquid enters the
  pump, and suction will get created. The pressure
  difference will get created over the sides. The
  liquid will move from the teeth side of the pump,
  and it will move alongside the casing. 
• As the gears continue to rotate against the pump
  casing, the liquid gets forcefully pressurized at
  the pump's outlet. So, the trapped fluid will
  move around the casing from the inlet to the
  outlet, which will ultimately increase the
  pressure in the fluid. 
• At the discharge side, the two gears will again
  interlock with each other than the expanded
  volume that we will be getting at the inlet side,
  and on the opposite side, the volume will get
  reduced.
•  And due to that reduction in volume, the fluid
  will then be pressurized then the fluid will be
  forcefully pushed out of the casing from the
  discharge pipe. Ultimately you will be getting
  the pressure at the discharge side also.
• Due to the continuously rotating action of the
  gears, the fluid will get entrapped into the
  casing, and it will move against the casing, so
  this will also increase the pressure in the fluid
  itself, and the liquid is thrown out with a
  higher velocity and higher pressure. 
• Once the fluid is transferred from the suction
  side to the discharge side, the fluid cannot go
  back to the suction side. So, all these functions
  make this type of pump a positive displacement
  type pump.

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Internal Gear Pumps and Their Working

• Internal gear pumps are specialized arrangements
  of the gear. They work on the same principle as
  that of the external gear pump, but it has a
  different design from external gear.
• In the internal gear pump case, the two different
  gears are the internal gear that is the driven
  gear. This particular internal gear will have the
  teeth projecting inside the second gear. 
• The driven gear, that particular driven gear, is
  like continuously meshing with the internal gear.
  That particular, driven gear is placed
  eccentrically, and a void is created. To avoid
  that particular void, a spacer is used. The
  spacer is fitted in the internal gear pump. 
• The primary function of this spacer is to reduce
  the area to occupy that space and increase the
  pressure in the fluid to maintain a close
  tolerance. In any of the gear pumps, the close
  tolerances are always essential to create a
  pressurized fluid.
• As the internal gear pump starts rotating, the
  gears will come out of the machine, creating the
  expanded volume. The pressure difference gets
  created the liquid will flow inside the internal
  gear pump. 
• The liquid is forcefully rotated between the
  meshing of the gear and between the spacer. There
  is a small clearance between the gear and the
  spacer so that the liquid will flow from the
  cavities in the clearance. 
•  Then the liquid is forcefully thrown out of the
  discharge outlet. So on the discharge side, the
  gears will interlock with each other, and the
  area will get reduced.

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Features Of The Gear Pump

• ? The gear pump has a compact and simple design.
• ? It has fewer moving parts.
• ? The pressure developed in the gear pump is less
  than that of the reciprocating pump but more than
  a centrifugal pump.
• ? The flow rate will be less than that of the
  centrifugal pump but more than the reciprocating
  pump.
• ? It can create a pressure of upto 210 bars that
  is equivalent to 3000 psi.
• ? The material of the construction used in the
  gear pump is cast iron or else stainless steel.
• ? It is also suitable for corrosive liquids like
  sulphuric acid, sodium hydrochloride, ferric
  chloride, and sodium hydroxide.

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Conclusion

• Gear pumps are positive displacement type pumps.
  They are of two types that work according to the
  aggressiveness of the liquid. The gear pump is
  mainly suited for aggressive liquids and also for
  liquids with higher viscosities.

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