J. F. Holloway.
Fig. 307.
COMPOUND DUPLEX PUMPS.
(With The Deane Switch Valve.)
The application of this valve is shown in [Fig. 307], on the opposite page. It can be attached to any regular Compound or Triple Expansion Pump, and if not in use does not in any way impede the regular running of the machine.
The Deane switch valve is a device by which compound low service pumps may be converted into powerful fire pumps. This appliance consists of a valve of such construction that steam may be allowed to enter the cylinders as usual for compounding, or may be diverted by simply moving a lever, when all four cylinders receive steam at boiler pressure, each exhausting independently to the atmosphere. The change makes each steam cylinder available for its maximum power, all four cylinders develop their full power, and its effect can be utilized in powerful fire streams.
It should be borne in mind in justice to the manufacturers that the Deane switch valve is not to be classed with the ordinary two or four-valve arrangement, which, while admitting initial steam to the second cylinders, develops no power in the first, or, as it is sometimes arranged, uses initial steam in all four cylinders and develops less power than if the second cylinders were used independently.
This valve is recommended by the Insurance companies, and compound duplex pumps fitted with the Deane switch valve will be accepted in place of the Underwriter pump of similar capacity. This valve is also frequently used where two widely differing water pressures are required for other purposes than for fire protection.