Fig. 503.
TURBINE PUMPS.
The Turbine Pump is suited to very high lifts, even exceeding 2,000 feet. An admirable example of this class of pumps is described in the following paragraphs:
The Worthington turbine pump has been developed by a long series of experiments. The diffusion vanes which form the distinguishing feature, take the place of the usual whirlpool chamber and assist in bringing the water to rest without internal commotion or shock. They correspond in function to the guide vanes of turbine water-wheels. One of the difficulties presented by high-lift centrifugal pumps has been the great peripheral speed required when only a single impeller is employed. This has been overcome by mounting a number of discs or impellers, each operating in a separate chamber, upon a single shaft and passing the water through the impeller chambers in succession. The lift can thus be multiplied three, four or five times, while the number of revolutions is kept within bounds. It has been demonstrated that on the same work and within reasonable limits, multi-stage centrifugals are more efficient than single-stage pumps, the increased efficiency being due to a decrease in the frictional losses coincident with the reduced peripheral speed of the impeller.
It is well known that the turbine water wheel was perfected less by mathematical processes than by intelligent cut and try methods. It has been the same with the turbine pump, whereby the vanes and passages have been shaped and tested by practical experiments, followed in each case by comparison of results. The constant aim has been to avoid eddies and secure a favorable discharge of the water.
Note.—At the St. Louis World’s Exposition three of the 36-inch Worthington turbine pumps, each of a capacity of 35,000 gallons per minute against 160 feet head, supplied the Grand Cascade.
