pump types

                                                               Intro pumps

     

A pump is a device that moves fluids (liquids or gases), or sometimes slurries, by mechanical action.
 
 1 Types
 2 Pump repairs
 3 Applications
 4 Specifications
 5 Pumping power
 6 Efficiency

Types:-

     1.1 Positive displacement pumps
         1.1.1 Positive displacement pump behavior and safety
         1.1.2 Positive displacement types
                1.1.2.1 Rotary positive displacement pumps
                1.1.2.2 Reciprocating positive displacement pumps
                1.1.2.3 Various positive displacement pumps
                      1.1.2.3.1 Gear pump
                      1.1.2.3.2 Screw pump
                      1.1.2.3.3 Progressing cavity pump
                      1.1.2.3.4 Roots-type pumps
                      1.1.2.3.5 Peristaltic pump
                      1.1.2.3.6 Plunger pumps
                      1.1.2.3.7 Triplex-style plunger pumps
                      1.1.2.3.8 Compressed-air-powered double-diaphragm pumps
                      1.1.2.3.9 Rope pumps
   1.2 Impulse pumps
     1.2.1 Hydraulic ram pumps
   1.3 Velocity pumps
      1.3.1Radial-flow pumps
      1.3.2Axial-flow pumps
      1.3.3Mixed-flow pumps
      1.3.4Eductor-jet pump
  1.4 Gravity pumps
  1.5 Steam pumps
  1.6 Valveless pumps

 deff:-

1.1 Positive displacement pumps

         A positive displacement pump makes a fluid move by trapping a fixed amount and forcing (displacing) that trapped volume into the discharge pipe.

Some positive displacement pumps use an expanding cavity on the suction side and a decreasing cavity on the discharge side. Liquid flows into the pump as the cavity on the suction side expands and the liquid flows out of the discharge as the cavity collapses. The volume is constant through each cycle of operatio

    1.1.1 Positive displacement pump behavior and safety:

          Positive displacement pumps, unlike centrifugal or roto-dynamic pumps, theoretically can produce the same flow at a given speed (RPM) no matter what the discharge pressure. Thus, positive displacement pumps are constant flow machines. However, a slight increase in internal leakage as the pressure increases prevents a truly constant flow rate.

A positive displacement pump must not operate against a closed valve on the discharge side of the pump, because it has no shutoff head like centrifugal pumps. A positive displacement pump operating against a closed discharge valve continues to produce flow and the pressure in the discharge line increases until the line bursts, the pump is severely damaged, or both.

A relief or safety valve on the discharge side of the positive displacement pump is therefore necessary. The relief valve can be internal or external. The pump manufacturer normally has the option to supply internal relief or safety valves. The internal valve is usually only used as a safety precaution. An external relief valve in the discharge line, with a return line back to the suction line or supply tank provides increased safety.

  1.1.2 Positive displacement types:

 A positive displacement pump can be further classified according to the mechanism used to move the fluid:

1:Rotary-type positive displacement: internal gear, screw, shuttle block, flexible vane or sliding vane,  circumferential piston, flexible impeller, helical twisted   roots (e.g. the Wendelkolben pump) or       liquid-ring pumps

2:Reciprocating-type positive displacement: piston or diaphragm pumps

3:Linear-type positive displacement: rope pumps and chain pumps

  1.1.2.1 Rotary positive displacement pumps:

   These pumps move fluid using a rotating mechanism that creates a vacuum that captures and draws in the liquid[citation needed][dubious – discuss].

Advantages: Rotary pumps are very efficient[citation needed] because they naturally remove air from the lines, eliminating the need to bleed the air from the lines manually.

Drawbacks: The nature of the pump requires very close clearances between the rotating pump and the outer edge, making it rotate at a slow, steady speed. If rotary pumps are operated at high speeds, the fluids cause erosion, which eventually causes enlarged clearances that liquid can pass through, which reduces efficiency.

Rotary positive displacement pumps fall into three main types:

1:Gear pumps - a simple type of rotary pump where the liquid is pushed between two gears

2:Screw pumps - the shape of the internals of this pump is usually two screws turning against each    other to pump the liquid

3:Rotary vane pumps - similar to scroll compressors, these have a cylindrical rotor encased in a similarly shaped housing. As the rotor orbits, the vanes trap fluid between the rotor and the casing, drawing the fluid through the pump.

  1.1.2.2 Reciprocating positive displacement pumps:

   Reciprocating pumps move the fluid using one or more oscillating pistons, plungers, or membranes (diaphragms), while valves restrict fluid motion to the desired direction.

Pumps in this category range from simplex, with one cylinder, to in some cases quad (four) cylinders, or more. Many reciprocating-type pumps are duplex (two) or triplex (three) cylinder. They can be either single-acting with suction during one direction of piston motion and discharge on the other, or double-acting with suction and discharge in both directions. The pumps can be powered manually, by air or steam, or by a belt driven by an engine. This type of pump was used extensively in the 19th century—in the early days of steam propulsion—as boiler feed water pumps. Now reciprocating pumps typically pump highly viscous fluids like concrete and heavy oils, and serve in special applications that demand low flow rates against high resistance. Reciprocating hand pumps were widely used to pump water from wells. Common bicycle pumps and foot pumps for inflation use reciprocating action.

These positive displacement pumps have an expanding cavity on the suction side and a decreasing cavity on the discharge side. Liquid flows into the pumps as the cavity on the suction side expands and the liquid flows out of the discharge as the cavity collapses. The volume is constant given each cycle of operation.

   Types Reciprocating positive displacement pumps:-

   1: Plunger pumps

   2: Diaphragm pumps

   3: Piston pumps 

   4:Radial piston pumps

1.1.2.3 Various positive displacement pumps:-       

The positive displacement principle applies in these pumps:

1. Rotary lobe pump
2. Progressive cavity pump
3. Rotary gear pump
4. Piston pump
5. Diaphragm pump
6. Screw pump
7. Gear pump
8. Hydraulic pump
9. Rotary vane pump
10. Peristaltic pump
11. Rope pump
12. Flexible impeller pump

   1.1.2.3.1 Gear pump

This is the simplest of rotary positive displacement pumps. It consists of two meshed gears that rotate in a closely fitted casing. The tooth spaces trap fluid and force it around the outer periphery. The fluid does not travel back on the meshed part, because the teeth mesh closely in the center. Gear pumps see wide use in car engine oil pumps and in various hydraulic power packs

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