Reciprocating versus Turbine Pumps.
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At the annual meeting of the Association of Professional Fire Brigade Officers, which was held last month at Westminster, Mr. William Inkster, the Firema,ster of Aberdeen, presented a paper dealing with a subject which is fraught with much interest at the present time to all those who are concerned with the introduction of selfpropelled vehicles into modern fire-brigade installations.
Mr. Inkster had chosen as a title that of "Reciprocating versus Turbine. Pumps." He said that his reason for the choice of such a subject was the fact that so many revolutionary improvements had recently been introduced in the construction of efficient fire-fighting apparatus, and that one of the most-remarkable changes in this respect was the increasing adoption of the turbine or rotary type of pump, in preference to the reciprocating pattern, which, in one form or another, had done such good service.
In the course of a brief review of the essential differences between the reciprocating and turbine form of construction for fire pumps, Mr. Inkster stated that it was apparent to him that, on every occasion when he had noted that a change from one, two or more deliveries from a reciproeating fire pump had been necessary, great care had to be exercised in the manipulation of the steam regulator and of the by-pass, in order to keep the steam plant under fairly constant
conditions. Again, he said, in the event of two, three or more additional lengths of hose having to be attached to those which were already in use • ' the speed must be reduced for reasons well known to fire-brigade officers." In his opinion, the rotary or turbine type of pump had overcome those objections in addition to others which he would mention. The reciprocating pump had so many working parts compared with that of the rotary construction, that a great deal more energy was lost in overcoming friction in the former type.
The multi-stage type of turbine was 111pntioned, and favourable comment was made upon the opportunity which this class of design gave to enable the attainment of the necessary high pressures at relatively-low pump speeds. A notes: orthy advantage sf the rotary machine was its ability, owing to the absence of pistons, valves and pump levers, to draw and discharge muddy water or liquids containing a large proportion of foreign matter, without the slightest fear or danger of the pump's becoming injured or choked. This, Mr. Inkster stated, was a point in favour of such a design which should commend itself to every practical fire-brigade officer.
A further advantage was secured with this form of construction owing to the absolute freedom from pulsation, and its relatively-low degree of vibration. This, naturally, would effect a very great saving in the wear and tear of hose and suction pipes when they are exposed to such rough surfaces as macadamized roads, etc.
Mr. Inkster continued: " In a vertical lift, say, from 28 ft. to 30 ft., which is the maximum for any ordinary pump to draw, owing to atmospheric influences, I am of opinion that the turbine machine has again the advantage. In this respect, the water is kept on the move, so to speak, with a constant upward-flowing tendency, through the suction pipe towards the impellers ; it is not jerked by any series of pulsations, as is the case with a plunger or reciprocating pump. A jet from a turbine maeltine
—basing my opinion upon observations noted at the Glasgow test—is very similar to that from a street hydrant, inasmuch as the branch, even under 120 lb. pressure at the pump was quite easily held and controlled, the flow of water being steady and the jet reaching a high altitude unbroken, thus giving better results than its plunger competitor. That result was achieved even although the conditions of the demonstration at Glasgow, from a practical point of view, were in favour of the reciprocating machine."
In the Aberdeen Firemaster's opinion, a further advantage of the turbine pump was the fact that its no 'mal maximum delivery could readily he exceeded by speeding up the machine. He considered that this was a point which would be appreciated by every officer, from the point of view of its utility for cooling-dowi purposes, after a fire had been nominally subdued. " The efficiency of a reciprocating pump," he said, falls rapidly away when required to work over its given capacity." The method of priming one turbine pump, from a water tank carried on the machine for that purpose, and the ability to couple such a pump direct to street hydrants, and thus to allow a free passage of water into the turbine chamber at full hydrant pressure, were lastly noted.
In conclusion. Mr. Inkster expressed himself as in favour of the turbine pump. when compared with its longestablished competitor of the reciprocating type, on the following counts: its more-economical initial outlay and subsequent maintenance : its absence orvibration and pulsation, when at work tinder all ordinary conditions; and its better control and more-flexible
working conditions.