PUMPS

the principal developments in the science of pumping since the year 1910 consist mainly in improve- ments in the design of the centrifugal and reciprocating pumps for pumping large volumes of water and sewage, the special forms of pumps for pumping crude and refined oils and petrol due to the rapid growth of the motor and fuel oil industries, improvements in pumps for handling highly viscous substances such as tar, glycerine and molasses, and in pumps for dealing with highly corrosive substances, mine waters and liquors used in the treatment of ores for the extraction of metals. large volume pumps.—for pumping, the centrifugal pump is practically universal. the high-pressure turbine pump has undergone considerable development in simplicity of construc- tion, ease of manufacture and efficiency and an enormous increase in the pressures involved. a turbine pump has been produced to replace the three-throw hydraulic ram pump with the accumu- lator. the pumping of boiler feed water has resulted in the production of the long-stroke pump, which has gradually given way to the turbine pump, where a single pump can be used, to pump hot water at different pressures to suit different boilers. the turbine pump is now made in two distinct varieties, the non-regulating type and the regulating type. the roturbo and sunturbo pumps automatically prevent the sudden demand for power when the load is taken off. the turbine pump is employed for deep well pumping, but difficulties arise chiefly from the confined nature of the space into which the pumps are placed and to the impossibility of using oil for lubricating the bearings. the problem of designing bearings for this type of pump cannot as yet be said to have been solved. such bearings are lined with lignum vitae, or various forms of rubber. the pumping of oil—the first successful oil pump, intro- duced by worthington, is characterised by its lost motion device. it is now employed in most industries for occasional work where certainty of operation is required without skilled attention. most of the successful oi1 pumps are of the reciprocating type, designed more or less on the worthington principle. as oil is ‘viscous and its resistance to flow is greatly affected by tempera- ture, the pumps are designed with very large valve chambers and provided with steam cylinders capable of coping with the high pressures necessary. the rotary pump has been consider- ably developed for this class of work. the pumping of hot oils during the process of refining has produced several special forms of pumps. in one type the hot oil does not enter the actual pumping cylinder, but a buffer of cold oil separates the working cylinder from the valve box. the difficulties in pumping petrol lie in its extreme limpidity in con- trast with the high viscosity of fuel and crude oils. the semi- rotary and the rotary pumps are common forms for this purpose. the roadside pump is a modern feature and is designed to deliver measured quantities of, say, 1 to 25 gal. to motor cars on the road. the convenience of obtaining petrol in this manner is sufficient to overcome the inaccuracies of the methods employed, to correct which improvements are being made. one ingenious roadside pump uses the pressure of a high level water tank to force the petro! through an ordinary water meter into the pur- chasers’ tanks. this method avoids loss due to evaporation and the danger of fire. displacement systems for handling inflam- mable liquids in order to reduce the fire risks have been developed. the pumping of oils from mines is a recognised difficult opera- tion. it is usual to bale out oil from a deep well, but it is now possible to pump sand and oil without the danger of the sand eroding the pump barrel. in one form of pump the valves lie deep down among the sand-laden oil, and the pump barrel itself, operated by mechanism at the top, works in a buffer of clean water and oil. corrosive liguids,—before 1910 the ordinary acid egg was almost the universal appliance for raising corrosive liquids, and improvements in pumping first showed themselves in attempts to make the acid egg an automatic and self-acting machine. in spite of several automatic elevators it cannot be said that this method of pumping is a success. then came the acid resisting alloys of the iron silicon type. many pumps were made 265 of these alloys, but owing to the high cost and the brittle char- acter of the alloy success was limited. a distinct advance was the use of an ordinary pump acting on an inert substance which separated the acid to be pumped from the working mechanism, such as the ferraris, in which a buffer of mineral oil is used. leakage at the gland of an acid pump must be avoided and many attempts have been made to produce a glandless pump. in one type the resistance of an annular film of acid round the pump rod js relied upon to control leakage within small limits, suitable means being taken to collect the flow and return it to the suction side of the pump. the use of ebonite for making pumps has undergone very little change. diaphragm pumps separating the working mechanism from the acid side have not shown much development. improvements in the compounding ef rubber enable the design of a bellows pump free from all gland leakage to be perfected. the centrifugal pump for cor- rosives is made of lead and some forms are lined with rubber and ebonite. an ingenious earthenware acid pump, made of a mixture capable of resisting heat, has been produced. the acid- egg type of pump has been adopted for pumping sewage in level districts. the apparatus works automatically and can be left for long intervals without attention. for pumping acid fumes the nash-hytor pump consists of a rotor working in an elliptical chamber and so arranged that the inlet and outlet sides are sepa- rated by a layer of water, which is kept to the surface of the chamber by the centrifugal action set up by the rotor, no valves being necessary. it is being used to compress air for operating the sewage ejector pumps in the streets. the pumping of solid-laden hquids has been successfully accomplished by the gwynne-pennell trap, in which the solids are ingeniously trapped and conveyed to the suction side without having to pass through the pump. constantinesco uses a rapidly operated pump for the production of waves in any fluid in a closed system for the transmission of power from point to point (see ‘transmission gear, variable). first used for firing a gun on the fokker plane, its use has been extended to the work- ing of rock drills in mines. air-lift-—the air-lift has received considerable attention. jn an extensive series of tests made on a mine in california efficiencies of 70° were obtained. the researches of dr. owen, investigated by swindin, show that the air-lift has possibilities of high efficiencies provided care is paid to the correct design of the footpicce. the use of the air-lift for pumping molten metals is progressing and its action is seen in the latest type of sub- merged flame burner. in an ingenious form of chain pump, a development of the old rope pump, by the application of the principle of surface tension a series of cells attached to a travel- ling band can be filled with water. a curious combination of the displacement pump has recently appeared under the name of the “f hydrautomat,” in which a large quantity of water falling through a short distance raises a portion of itself to some greater height. it performs the same function as the well-known hy- draulic ram and works by alternately compressing and exhaust- ing air in a series of containers. mchell’s studies in lubrication have revived the old swashplate, and pumps having this as a vital element are now appearing. pumping by direct explosion of a combustible mixture in contact with the water has been the subject of investigations by humphrey. in the artificial silk industry (see artificial silk) special small pumps are used; usually small rotary appliances similar to the sud pump on automatic machine tools are used for squirt- ing viscose solutions through the dies into the coagulating bath. pipe-lines, etc —much ingenuity has been shown in the study of pipe-lines, tubes, hose and the manner of making joints. the difficulty of making a satisfactory joint in a pipe for petrol still attracts inventors. the best known method at present seems to be to use metal-to-metal joints and to rely on extreme good workmanship. joints in the large mains are made by means of screwed couplings made to gauge. petrol hose is now manu- factured and some forms consist of.a metallic lining reinferced with rubber and canvas. the “ victaulic ” joint has rendered possible the making of pressure and vacuum tight joints at low 266 cost and with great ease. slight irregularities in the alignment of pipes do not affect this type of joint. theory.—on the theoretical side the reynolds-stanton law of viscous flow has been developed in a form suitable for use by ordinary hydraulic and chemical engineers. dr. ing. bruno eck has applied the theory of aeroplane lift and drag (lanchester and prandtl) to the design of turbine and centrifugal pumps. the theory and practice of centrifugal and turbine pumps are at variance and cannot be reconciled by the old hydrodynamic theories, but eck has shown that the streamline theory of lan- chester and prandtl can be applied to the working of these pumps and thus account for the divergencies. the older theory depended upon the principle of a non-viscid frictionless fluid, but the reynolds theory and its extension by prandtl have put the element of viscosity into the theory with the result that the performance of centrifugal pumps can be explained on theoretical grounds. much light has been thrown on this subject by the researches of camichel and m. m. l. escande and m. ricaud at the toulouse university, who have rendered visible the stream lines, thus facilitating enormously the ease of study. photo- graphic study of the problem is also being made by prasil and oertli at ziirich. photographs of streamlines round the impeller blades of a turbine pump reveal the causes of the loss of efficiency. reference should be made to the work of prof. th. von karman and his methods of turbine design. in his view turbine design is much more difficult than the study of the correct design of an aeroplane wing. bibliography.—e. j. marey, smithsonian institution, report of board of regents (1869); o. reynolds, “‘ an experimental investiga- tion of the circumstances which determine whether the motion of water shall be direct or sinuous, etc.’”?’ phil. trans. roy. soc., vol. 174 (1883); e. j. marey, ‘ la chronophotographie,” annales du conservatorie des arts et metiers (1899); f. kgnig, der i1ydrotekt (1902-3); t. von karman, ‘‘ untersuch. tiber knickfestigkeit,”’ mitt. tiber forschungsarbeiten a, d. g. des ingenieurwesens, vol. 87 (1910); a. h. green, pumping machinery (1911); l. c. loewenstein and c. p. crissey, centrifugal pumps, their design and consiruc- tion (1911); t. von karman, “ festigkeitsversuche unter allseitigem druck,” afzit. diber forschungsarbeiten a. d.g. des ingenteurwesens, vol. 113 (1912); c. g. de laval, centrifugal pumping machinery (1912); f. neumann, die zentrifugalpumpen mit besonderer berticks. der schaufelschnitie (1912); a. pfarr, die turbinen fiir wasser- kraftbetrieb, 2nd ed. (1912); franz prasil, technische hydrodynamik (1913); t. e. stanton and j. r. pannell, ‘‘ similarity of motion in relation to the surface friction of fluids,” nat. phys. lab. collected researches, vol. 2 (1912); j. r. pannell, and w. f. higgins, ‘* report on tests of fuel oils, june 1914," nat. phys. lab. collected re- searches, vol. 13 (1916); e. w. sargeant, centrifugal pumps and suc- tion dredgers, 2nd ed. (1918); g. constantinesco, theory of sonics (1920); h. halder, pumpen und kompressoren (wiesbaden 1920); g. belluzzo, i/ calcole ela installazione delle moderne turbine idrau- liche (milan, 1921); j. w. cameron, centrifugal pumps (1921); j. s. owen in engineering (sept. 23 1921); l. prandtl, ergebnisse d. aerodynamischen versuchanstalt 2u gettingen (1921, etc.); w. walker fyfe, automatic pumping (1922); g. m. camichel, comptes rendus de l’' academie des sciences, vol. 177 (1923); vol. 80 (1925) etc.; r. 5s. danforth, friction of oi in pipes (san francisco, 1923); c. v. drysdale and others, the mechanical properties of fluids (1923); m. lo preste, le turbine idrauliche (milan, 1923); g. constan- tinesco, variable transmission (1924); “‘ elements of the lanches- ter-prandt] theory of lift and drag,” engineering (jan. and feb. 1924); also published as a separate pamphlet; n. swindin, afodern theory and practice of pumping (1924); c. m. camichel, a ppiica- tions des lois de similitude a l’ etude des phenomenes qui se produisent a laval d'un corps immerge dans un fluide visqueux en mouvement (1925); b. eck, turbinentheorie (1925); wissenschafilicken gesell- schaft fir luftfahrt, munich report (1925); l. escande and h. ricaud, “‘ lois de la similitude des fluides incompressibles,”” pub. de institut electrotechnique et de mechanique appliguee de v universite de toulouse (1925); b. eck, ‘“‘ hydrodynamical theory of turbine and centrifugal pumps,” engineering (jan. 22 and 29 1926). see also recent papers by c. m. camichel in les annales de la faculte des sciences de toulouse; les travaux du 2me et de 3me congres de la houille blanche; le bulletin de la societe des ingenieurs civils; les publications de i’ institut electrotechnique et de mechanique appliquee del’ universite de toulouse; l' eclairage, lumiere ilectrique, la revue generale de l’electricite, le genie civil, la technique mederne; le bulletin special de la societe hydrotechnique ates”