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The History and Development of the Turbine Pump.

25th July 1912, Page 7
25th July 1912
Page 7
Page 8
Page 7, 25th July 1912 — The History and Development of the Turbine Pump.
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A Precis of an Interesting and Informative Paper which was read before the Institute of Mechanical Engineers and which has Especial Interest at the Present Time.

In our last issue we wrote editorially of the inevitable supersession of the reciprocating pump by the inure symmetrical turbine. There still lingers in the minds of certain firemasters in this country and abroad the conviction—and a very conservative one indeed it is—that the reciprocating pump cannot be beaten for efficiency as a type, and this somewhat unenlightened view is still from time to time given effect in the decision of isolated fire-brigade committees charged with the spending of public money upon the latest self-propelled fire-brigade plant. In the course of those of our comments to which we have already referred, we promised to publish in the present issue a precis of an authoritative paper upon the turbine pump which was read in the early part of this year before the Institute of Mechanical Engineers, but to which, owing to the considerable congestion of our news services at the time, we were unable to give publicity. Dr. Hopkinson's paper may be read now with renewed interest by those firemasters and members of fire-brigade committees who still—and we think somewhat reluctantly—cling to the fetish of the plunger pump.

" The Evolution and Present Development of the Turbine Pump," was the title of the paper which was presented, at the February meeting of the Institution of Mechanical Engineers, by Dr. Ed. Hopkinson, of Cambridge, and Mr. A. E. L. ChorRon, of Manchester. There was much in the paper which is of considerable interest to professional readers of our Fire-Brigade pages. We give a brief summary below of the authors' remarks.

Although the rotary principle of operation has long been the accepted ideal for highly-efficient machinery, it is only during recent years that there has been any very serious effort to develop the turbine pump for high-lift duty ; the acceptance of this type of pump, as correct engineering practice, only took place about five years ago, but at present there seems some difficulty in finding a service to which the principle cannot successfully be applied. The turbine, or centrifugal pump, in its simplest form, is a very old idea ; we find references to it in a paper which was read, at the beginning of the 18th century, by Denis Pap in, a French physician and physicist, and a Fellow of the Royal Society. Papin's drawings show clearly the volute casing of the modern centrifugal pump, but as he had no means of driving his pump except by hand power, it was over a century before his ideas were developed and scientifically applied. At first, this class of pump was only thought to be useful for low-lift service—a, misguided notion which took many years to overcome. The low-lift idea, however, was not shared by at least one pioneer, to whom much of the present success is due ; we refer to John Gwynne, who in the year 1851, took out a patent (No. 13,577), the specification of which contains many claims that go to show that he was fully alive to the possibilities of the turbine pump. His specification seems to contain the first proposal to make use of centrifugal impellers arranged in series, and, although the form he showed does not indicate veryhigh efficiency, it was a conception very much in advance of the period.

In the year 1875, Professor Osborne Reynolds invented a turbine pump in which the impeller delivered the water to tangent guide vanes; the mouths of the guide channels could be regulated so as to raise the efficiency of the pump for small output, a device, however, which has not been used on many modern pumps. Following Reynolds, the next practical step appears to have been taken by Messrs. Mather and Platt, who made a pump for the engineering laboratory of the Owens College, Manchester, in 1887; at any rate, the results obtained by that pump appear to have been the first of • sufficient value to be recorded. That pump had four impellers arranged in series, and these, when driven at 1500 r.p.m., gave a head of 148 ft. of water, or 37 ft. per chamber. It was tested by Professor Reynolds, who found that it showed an efficiency of 58.5 per cent.—a very-high result for a pump which was designed and built 25 years ago. Messrs. Mather and Platt took up its manufacture, on commercial lines, in the year 1893.

The authors, after dealing with many interesting and highly technical details, made the following statements concerning turbine pumps for modern firebrigade purposes :-

" The capacity varies usually from 350 to 1000 gallons per minute, against a head of 250 to 300 feet. The pump has a single chamber and is designed to fit on the back part of the chassis of an automobile, and to be driven by an extended shaft from the engine. The regularity of the flow of water delivered renders the holding of the hohe-jets much easier and the action of the turbine-pump allows the shutting off of any particular jet, or of all the jets, without any tendency to burst the hose-pipes, as may be the ease with a reciprocating pump. Further, the pump is much lighter than a corresponding pump of reciprocating type, and takes up considerably less apace. The difficulties incident to starting with a heavy auction can be met by the provision of a small auxiliary pump which exhausts the suction pipe, thus causing the water to fill the turbine-pump. As soon as the turbine-pump has developed its head pressure, the auxiliary pump can be put out of action, and the turbine-pump will continue to work with suction lifts up to at least 80 per cent. of the height of the barometric water column."

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