EFFICIENCY TEST OF WATER WORKS PUMPING MACHINERY
Two Fort Smith, Ark., Pumping Units and Turbines Tested for Speed and Capacity-Excellent Showing of Units
TESTS for efficiency of water works pumping machinery are always interesting and instructive and a series of acceptance tests recently conducted under the supervision of the consulting engineer of Fort Smith, Ark., at the municipal plant of the city of two new Lea-Courtenay 5,560 g. p. m. pumps, show some significant results that may be of some use to other water departments. The pumps are direct connected to two Terry steam turbines with normal rated speed of respectively 4,402 and 4,530 r. p. m.
Description of Two Pumping Units
The two units consist of a high lift and a low lift pump. The low lift pump receives its supply of raw water from an adjacent stream and discharges into a settling basin while the high lift pump receives water from a clear well and discharges directly into the city mains and storage reservoir. A general description of the two units are tabulated below:
At a pump speed of 1,200 r. p. m. the high lift pump will deliver 3,000 g. p. m. under a total head of 325 feet. These conditions are required during certain fire emergencies. The turbine governor is provided with a speed changing device for controlling fire service speed conditions.
Both of the turbines are served by an Alberger 2,200 square foot water works type surface condenser. Air and non-cotidensable vapors are removed from the condenser by a two-stage occluder, equipped with a surface type intercooler. The condensate is removed by an Alberger duplex steam driven pump, equipped with an automatic hot well control. The condenser is installed in connection with the high lift pump. The reason for the condenser capacity noted is that it is proposed at some future date to connect the exhaust from a turbo unit into it.
Details of the Tests
The tests which were conducted on January 17 for the high lift pump and on January 18 for the low lift, resulted in the following figures:
Condensate temperatures could not be determined due to the fact that hot well control and scaling gland water, also condensate from first stage of occluder, entered condenser at points making accurate observations difficult. The expense of getting accurate measurements here did not seem warranted.
The engineer’s specifications covering the installation of these units did not permit of correction for moisture in the steam. Since the condenser is connected to the suction line of the high lift unit, it was necessary to test the high lift unit, with the low lift unit shut down, then arrive at the steam consumption of the low lift unit by testing both units simultaneously and deducting from the total steam used, that consumed by the high lift unit, as reflected by its individual test.
The contract covering the installation required that all auxiliaries be charged against the high lift unit. The auxiliaries are of ample capacity for 12,000 pounds steam per hour. Water delivered by the high lift pump was determined by a Simplex venturi meter; that from the low lift pump by measurements in the settling basins. The steam consumptions were determined by weighing water fed to boiler, and all pressures by tested gauges and mercury column.
Due to local conditions, it was not possible to extend the tests over a period in excess of one and one-half hours. In order to reduce chances of error to a minimum, the process of feed water weighing was gotten under way some time before each test was started; during this period, the normal pump capacities and heads were established and each test started at a time when all equipment was functioning in a normal manner.