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Chapter 17 to 18

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17. Discharge water volume

Discharge water volume may be determined by the following equation, using nozzle bore and nozzle spout pressure (measurable with a Pilot gauge).

Relationship among water discharge volume, nozzle bore and pressure at nozzle spout is tabulated below.

18. Water discharge from pump connected to fire hydrant

1) Open hydrant valve gently, withdraw iron rust, pebbles, with water, and connect suction hose.
2) Open hydrant valve fully, and then read vacuum meter (static pressure) while closing discharge valve on pump.
3) Read vacuum meter when opening discharge valve on pump to discharge water.
4) If vacuum gauge is read over 0.3 Mpa in clause 3) above, give up starting engine, or start it at a low speed.
5) When pump is operated and water is discharged, the faster pump runs, the lower vacuum meter is read. Here, it is important not to let pressure decrease below 0.05 Mpa by decreasing speed or replacing nozzle with one having smaller diameter. (If static pressure is over 0.15 Mpa, the figure on vacuum meter will not drop below 0.05 Mpa in most cases.)
6) When the figure of vacuum meter pressure is more than 3/4 of static pressure when pump runs to discharge water, another pump can be additionally connected to the same hydrant.



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【参】BSI-EN:フッターナビ