Pump - SpeedyLook encyclopedia

History

The principle of the pump appeared as soon as the man knew to build an artificial habitat to protect itself from the natural elements. The requirement out of water necessary to its survival obliged it to find a transport system of this water, well or river with its habitat, it used simply the energy developed by its muscles to transport water using container natural or artificial, plus capacity and the distance were large plus energy spent was important. Until the beginning of the industrial era (fine of the 18th century) of the pumps were useful only for the transfer of water.

The Greek S and the Romain S were the first to use rotary systems to convey water.

All these systems were used to raise water in Aqueduc S feeding the cities and the baths. The Greeks and the Romans were among the first to pose the bases of the Hydraulique.

At the great time of the culture gréco-Roman of many principles of Physical and Hydraulique was discovered, but ever developed. The economic needs for this time did not require a mechanization of the production equipment. Energy necessary to the production was provided by an almost free labor (slaves). However as of this time the principles of the piston pumps, the centrifugal pumps and the vacuum pumps were discovered. The achievements implementing these principles were used however only with the demonstration of mathematical calculations (sets of intellectuals) or for the entertainments (Fountain, dancing waters, turns of magic etc), the lock S (in order to avoid the rates of too fast flow), desurgers on closed conduits (in order to avoid the bursting of the conduits) etc

It will be necessary to await the end of the 18th century so that the first pumps are really built and used in an industrial way.

Until the middle of the 18th century the economic needs were satisfied by the population growth which provided a cheap labor, the water mill remained the principal means of energy production. The demographic explosion in the second part of the 18th century obliged the production equipment to be mechanized.

The appearance of the Steam engine (Denis Papin) improved by the Scot James Watt allowed the mechanization of the industrial sectors where the needs were in full expansion (Coton, coal). The constant need for coal ore appeared with the development of the industrial era obliging the search for this one with depths which did not allow any more work open sky. The water infiltrations drowning the underground galleries continuously, one then used systematically pumps to evacuate this water. It is probably the first industrial use of the pumps. They were in fact piston pumps, Machine of Watt whose energy came from the vapor produced by water heated by a hearth, this open hearth regularly caused fires in the galleries (perhaps the origin of the name pumps with fire?).

It is always the energy need, this time electric which allowed one second evolution in the technique of the pumps to make its appearance.

Electrical energy allows the development of the pumps rotary principle, harnesses and centrifugal to feed the Alternateur S of the power stations of which the largest models were carried out by the Swedes, in fact since nearly one century no great principle of pump was not discovered. Only the materials used and the precision of machining made it possible the pumps to evolve to better outputs, of greater flow and high pressure. The only fact of using a liquid for manufacture where the needs for the manufacture of a product imply necessarily the use of pumps.

The pumps all meet the same need, to move a liquid of a point with another, to move this liquid it is necessary to communicate energy to him, the pumps fulfill this function, the engine which supplies the pumps transforms the thermal or electrical energy into mechanical energy to allow the movement of the bodies of the pumps, this mechanical energy is retransmise with the fluid. This fluid energy is translated in the form of flow (kinetic energy) and of pressure (potential energy) these energies will be exchanged and consumed in the circuits of the installation.

Classification

One can classify the pumps in several ways.

The movements retransmis with the bodies of the pumps are like all the mechanical movements of two great types:

Rotary
Rectilinear (alternate)

The mode of displacement of the fluid through the parts moving of the pump and their function makes it possible to classify the pumps in several families.

Transfer pumps

Rotary pump - axial -

Rotary pump - centrifuges -

Pumps of proportioning

Rotary pump - volumetric -

Reciprocating pump - volumetric -

Characteristics

the Rolled : it is the volume of fluid aspired and expelled for a movement. In the case of the rotary pumps the cubic capacity is expressed in (cm ³ /tour) or in (m ³ /rad).

the Flow: it is 1 volume of fluid transvased per unit of time, it is calculated according to the cubic capacity. In the case of a rotary pump, one a: Q (L/min) =Ve'*10^-3*N with NR (tr/min) rotational frequency of the engine actuating the pump and smVe' rolled in (cm ³ /tr).

the difference of Pressure: it characterizes the capacity of the pump to increase the pressure of the fluid which crosses it. The difference in pressure is weak for a centrifugal pump, it can be important for a positive-displacement pump

the volumetric output: it is the relationship between theoretical output (calculated with the cubic capacity) and the flow actually obtained. The volumetric output is always lower than 1 because of the escapes.

the mechanical output: it is the relationship between the couple (or forces it) theoretically necessary to produce the difference in pressure and the couple indeed necessary.

Note: Theoretical couple (N.m) = rolled (m ³ /rad) * difference in pressure (Pa)

the total output: it is the relationship between the hydraulic power provided by the pump and the mechanical power absorptive by the pump. It is also the product of the volumetric output by the mechanical output.

the hydraulic power is calculated by making the product of the flow by the difference in pressure.

P (W) =Q (m ³ /s) *ΔP (Pa)

Technique

Pump with beam

The Chadouf still used by certain African tribes.

Archimedes' screw

Axial rotary pump

The principle is close to that of the Hélice of Bateau. The displacement of the fluid is parallel to the axis of rotation.

It finds its application for great flows on the low uneven ones (weak difference in pressure), (several thousands of m ³ /h) in the field of water, circuit coolant (nuclear plants) or accelerators gravitating.

Centrifugal rotary printing-press

It is about a concrete application of the Centrifugal force. The principle used is that of the wheel with paddle S curved. The wheel is placed in an enclosure (the pump housing) having two or several openings, the first in the axis of rotation ( aspiration ), the second perpendicular to the axis of rotation ( repression ). The liquid taken between two paddles is constrained to turn with this one, the centrifugal force then pushes back the mass of the liquid towards the outside of the wheel where the only possible exit will be the opening of repression. Fluid energy is thus that coming from the centrifugal force.

For the same pump, the flow varies:

proportionally at the number of revolutions
with the difference in pressure between the entry and the exit: the higher this one is, the more the flow is weak
according to the characteristics of the fluid, such as viscosity, the temperature, the density

This variation of flow is given by the curve of operation of the pump given by the supplier of the pump. It provides the flow of the centrifugal pump is function the total height which it generates for a number of revolutions given. This curve is of parabolic pace

Components of a centrifugal pump 1 Wheel

The wheel (turbine, thruster) which constitutes the variable component of the pump communicates to the liquid part of the kinetic energy transmitted by the tree via its paddles (wings). There exist the three principal shapes of wheels:

closed wheel
half-open wheel
open wheel

The height generated by the wheel is function of the square circumferential speed. Consequently, for a height given to realize, plus the number of revolutions will be large plus the diameter will be weak and conversely. The more important the flow is, the more the section of entry and the dispatcher of exit is large.

2 diffuser or Pump housings

The pump housing, which constitutes the fixed element of the pump, is intended to collect the liquid which leaves the wheel, and to direct it, either towards the opening of repression, or towards the entry of the following wheel, according to whether the pump is mono or multi cellular. Moreover, it transforms into pressure part of speed. The principal shape of the body depends on the type of pump (mono or multi cellular).

3 Bodies of aspiration

It constitutes with the pump housing the fixed element intended to direct the liquid towards the entry of the wheel so that speed is uniform in all points.

4 Thrust

The forces which result from the action of the pressures on the flasks before and back of section different from a wheel give rise to a thrust generally directed towards the aspiration.

5 radial Push

This push, perpendicular to the axis, results from a bad distribution of the pressure around the wheel in the pumps with volute. The radial push preserves a fixed direction, changes direction around the nominal capacity, while being cancelled for this last. It involves a bending of the tree and subjects it to a rotational bending.

6 Sealing

Two principal systems are used to ensure the sealing of the shaft passage between the interior of the pump and the outside, generally subjected to the atmospheric pressure. It is:

Trimming with braids
Mechanical seal

Certain pumps tight standard do not require a system of sealing. It is:

Pump with rotor drowned
Pump with magnetic drive

Piston pump

This type of pump uses a sliding piston in a tight way in a cylinder to push back a fluid, allowed previously in the cylinder via a Clapet, of a Soupape or a Lumière, thanks to the aspiration caused by the retreat of the piston.

The performances are high:

Pressure several thousands of bar in particular for cutting jet of water
Flow up to 500 Liter S min
Output > 0,95

There exist various mechanical assemblies of which:

Axial-piston pump

The pistons are located the axis of transmission parallel to. They function thanks to:

an ice on which the shoes located in foot of pistons slip
a barrel into which are placed the pistons.

Certain pumps can function with aqueous solutions, even with pure water.

Radial-piston pump

The shoes of the pistons slip on an eccentric. The pistons are provided with repression and suction valves.

Pump with crankshaft

In the case of the use of a fluid not lubricating like water, with large flows and/or strong pressures, a crankshaft involves a whole of pistons on line. These particularly expensive pumps are seldom used.

Vane pump

This type of pump is especially used to decrease or increase the pressure of gases: Vacuum pump, compressing of air, air-conditioner, Refrigerating, etc

Pump with ram

System invented by the Brothers Montgolfier which makes it possible to transform the kinetic energy of water into wave of pressure by the phenomenon of the Water hammer: fast closing of a valve. This rather rustic pump has the principal disadvantage to let pass in against-low a great quantity of water of which only a small portion goes up towards the point of use. It has the advantage of not requiring any contribution of energy external apart from the water fall which gives birth to the phenomenon.

Pump with cups

Can be also cord pump, the cord sliding in a pipe drawing from the discs or the cups making assemble water.

Peristaltic pump

Vacuum pump

Gear pump

Pump Valdès

External bonds

Centrifugal pumps and volumetric - Principle of operation, advantages, disadvantages,…
Guide of manufacture of a cup pump
Exzenterschnecken-Motoren/Pumpen (of the excentré rotor pumps)
Humanitarian association using of the Valdès Pumps for African villages

Hydraulic pump dismounted to see the interior * Thesis of the engineer Rene Sparrow on his excentré stator pump

Manufacturers of pumps

Salmson
technical of the fluids
Johnson Pump
Börger
Albinpump
Grundfos

November 25th, 2007 with 05:27 (THIS)

Simple: Pump

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