US 1291130 A
Description (OCR text may contain errors)
A. W. PURCHAS.
EDUCTION PIPE FOR AIR LIFT PUMPS.
APPLICATION FILED SEPT- 29. I9I5 LQQIIJIUI W ,Dafa/M215 I/I//T/VESSES FWUCTFONFFPE FUR AllR-l'alllill FWS.
specitcation of Letters Patent.
patente aan. it, u
application nieu eptember 2u, 119th. Serial No. athlon.
To all whom t may concern Be it known that l, ARTHUR WILLIAM.
Fnizcrraaa subject of the King of Grreat lll ttl
` sures on the two sides of the plane shall be maintained; and consequently the Britain, and aresident of Westow, Kirkham Abbey, York, England, have invented a new and llmproved Fduction-Fipe for Juirdllift Pumps, of which the following is a full, clear, and exact description.
ll/ly invention relates to eduction pipes for air-lift pumps, andthe object thereof is to provide a simple and inexpensive pipe whereby the efliciency of the lift pump is i greatly increased by reducing the loss by high-entrance velocity and contracted water.
With the above and other objects in view, the nature of which will more fully appear as the description proceeds, the invention consists in the novel construction, combina-l tion and arrangement vof parts as herein fully described, illustrated and claimed. ln the accompanying drawings, forming part of the application, similar characters of reference lndicate corresponding parts in all the views. q
Figure 1 a diagrammatic view of a lift pump having an eduction pipe embodying my invention;
Fig. 2 is a slightly modified form thereof; and
Fig. 3 isa diagramfor explaining the reasons for the reduction in sectional area of the eduction pipe above the water level of the well or container where the eduction pipe is used.
Prior to air being injected into the eduction pipe, the water surface inside the pipe will stand at the same -level as that outside, that is,`at A A, Fig. 3, and the pressure on the upper and lower sides of the plane X X l will be equal. The injection of an air bubble into the eduction pipe must necessarily displace a volume of water equal to the volume of the air bubble; and since the bottom of the eduction pipe is open, the pressure on thel two sides of the plane X X will readjust itself to equality if disturbed. The weight of the bubble. of air injected being negligible, the' volume of water which-it displaces must move .upward within the eduction pipe in order that the balance of weights or res- 'water surface inside the eduction pipe will `be raised above the water surface A' A by an amount equal to g where 'v is the volume of the air bubble and a; the cross sectional area of the eductionv pipe. The air bubble then rises through the volume of water, and nally escapes into the atmosphere. 'lhe important point is that there is no loss by slip, of the energy originally contained in the air bubble until it breaks the surface of the liquid in the eduction pipe. Let Z be the lift in feet, and h the head in feet nu merically equal to g5'- llfucient air be introduced into the eduction pipe, the head h will ually exceed the lift Land then a volume of water equal to ah-al will be discharged from the to of the eduction pipe. rllhe loss of this weight of water from the eduction pipe will produce an unbalanced head equal to z/-Z on the under side of the plane X X, Fig. 3; and, therefore, this head h-Z will cause more water to dow into the eduction pipe.
Experiments have shown that a large proportion of this'head is wasted in forcing waterinto the space inside theeduction pipe which is ynot alreadyoccupied by air.
'lo eliminate this waste, the eduction pipe 4f has the cross-sectional area of the part .5,
` which is immersed into the water, as large as permitted by the well or container in which the pipe is positioned, therefore the losses due to highxvelocity and contracted Water passageways will be reduced, while the loss by slip in this length of pipe will be negligible, as can be seen from the theoretical discussion previously given.
lt is evident that enough space must be left about the portion of the eduction' pipe which is'submerged to facilitate the How of water to the eduction pipe. At a point near the pumping level, that is, A A (Figs. 1 and 2), the loss by slip'will begin to need consideration; and, to keep this loss within reasonable limits, the cross-sectional areain the eduction pipe per unit of time inl creases as the outlet of the pipe is reached. If the eduction pipe is kept of uniform cross-sectional area above the liquid level A A, as shown at 6 in Fig. 2, the frictional losses may be excessive; and to overcome this, the cross-sectional area of the eduction pipe is increased uniformly or in steps, as shown in Fig. l, 7 being the reduced portion above the Water level A A, While 8 is the enlarged cross-sectional area above the reduced area 7. By properly varying the cross-sectional area of the eduction pipe above the liquid level A A, the minimum sum of the losses due to friction and .to slip is attained.
While I have described the principle of operation, together With the eduction -pipe `which I now consider to be the best embodiment thereof, I desire to have it understood that the description and illustration Lesina@ thereof are merely illustrative, and that such changes may be made as are Within the scope of the appended claim.
An eduction pipe for air lifts, the cross section of Which varies in steps, the maximum cross section being at the bottom and adapted to be submerged, the minimum cross section following the maximum cross section, the section larger than the minimum but smaller than the maximum following the minimum section. y
In testimony whereof I'have signed my name to this specification in the presence of two subscribing witnesses.
ARTHUR WILLIAM PURCHAS,