GB1211678A - A fluid flow transfer system, especially for an industrial vacuum cleaner - Google Patents

Abstract

1,211,678. Centrifugal, axial-flow, rotary and reciprocating pumps. WIELAND K. G. Feb. 5, 1969, No.6269/69. Headings F1A, F1C and F1F. A fluid transfer system, especially for an industrial vacuum cleaner, comprises two motordriven parallel-connected pumps, one being a non-positive displacement pump and the other a positive displacement pump, the non-positive displacement pump being capable of higher delivery rates than the positive displacement pump but at a lower maximum pressure difference, and one of the connections to the non-positive displacement pump containing a non-return valve whereby the maximum pressure difference of the positive displacement pump is achievable and the maximum consumption of the combined pumps is less than the sum of the maximum power consumptions of the individual pumps. A centrifugal pump 1 and a sliding vane rotary pump 2, preferably driven by a common motor 8, have their inlets connected to a common suction line 3. In the case of an industrial vacuum cleaner, the suction line 3 is preceded by suction nozzles, a hose and a filter arrangement through which air, air-water or airdust mixture is drawn. When the fluid is of low specific gravity, i. e., is air or gas containing dust particles or like impurities, the delivery rate of the centrifugal pump 1 is substantially higher than that of the rotary pump 2, and the power input to the motor 8 is determined mainly by the power consumption of the centrifugal pump, which is at its maximum value. When the fluid is of high specific gravity, e.g. is sludge, the pressure difference necessary to draw the fluid up to the filter arrangement at which the solids are separated from the air or gas is higher than can be developed by the centrifugal pump 1, and a non-return valve 6 in the delivery or intake of the centrifugal pump closes. The delivery rate is now lower and is provided entirely by the rotary pump 2. The power consumption of the rotary pump 2 has now increased but the power consumption of the centrifugal pump is at a minimum. Consequently, the power consumption of the two pumps together is always less than the sum of their maximum consumptions. The centrifugal pump 1 may comprise several stages and may be replaced by an axial-flow pump. The sliding-vane pump 2 may be replaced by a pump of piston, oscillating or gear type. Several parallel-connected positive-displacement pumps and several parallel-connected centrifugal pumps may be used.