| 摘要 |
A pump assembly for use in fire fighting service is constructed of a single stage main pump and a two stage booster pump connected in series with the discharge of the main pump being connected to a first high flow rate fire fighting application and to the inlet of the booster pump and the discharge of the booster pump being connected to a second low flow high pressure fire fighting application. The impellers for both the main pump and the booster pump are mounted on a common rotating shaft so as to be driven thereby. A flow restriction and conduit means is provided to reduce the pressure on the booster pump seal. A by-pass conduit is arranged to conduct flow from the discharge of the booster pump back to the inlet of the main pump so that whenever the main pump is operated there will be flow through the booster pump to prevent overheating thereof.
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