This article first appeared in Practical Engineering 1940 Vol1 No21. The that follows is therefore valid as of 1940. This article discusses developments within the field of Engineering at the time.
The use of strong corrosive acids, of which examples in the engineering and allied industries are the pickling of sheets, bars, rods and wire, electro-plating and enamelling, has necessitated the development of special pumps which are resistant to such conditions.
Pulsometre Engineering Co., Ltd.
The special designs of centrifugal pumps made by the Pulsometre Engineering Co., Ltd., of Reading, Berks, are constructed of a suitable corrosion-resisting metal, or stoneware, according to the nature of the liquid to be pumped.
The “Lex Pump”
For example, the "Lex" pump of the single impeller type, suitable for heads up to 180 ft., has a plain volute casing, split vertically, having the two halves bolted together, with a large-diameter shaft carried in ball or roller bearings, and two external bearings, the whole being fixed on a pressed-steel base plate.
This is bolted to an extension base plate for direct-coupled electric drive, the pump shaft having a flexible coupling for the purpose. Any method of driving can, however, be adopted, and one modification has an extended shaft with belt or rope pulley, single or fast and loose. Also the internal neck bush is small, to serve as a check on the sealing water and not to support the shaft. The pump may be right or left hand, the position of the discharge branch can be "supplied as required, and if necessary the extension base plate may also be of bronze, or other corrosion-resisting metal. Suction and discharge pipes are of a size to suit the conditions.
Typical of the performance against a head of 180 ft. is a "Lex" 1 1/2in. pump (being the delivery-pipe diameter) which has a 21/2in. suction, and will deliver 110 gallons of water per minute with a speed of 1,960 r.p.m. At lower heads the speed is reduced for the same duty, being, for example, 1,135 r.p.m. at 60 ft. head.
Four Standard Sizes
These pumps also are in four standard sizes, l 1/2in., 2in., 3in. and 4in. delivery, and operated at different speed ranges. Thus the 4in. size with 5in. inlet at 180 ft. feet head has a duty of 550 gallons of water (or equivalent) per minute, running at 1,625 r.p.m., whereas at 60 ft. the speed is 940 revs.
For particularly severe conditions of corrosion, and of abrasion in the case of liquids containing finely-divided solids, such as grit, sand, and coal dust, special modifications have been designed. In these the parts most affected are renewable.