POWER PLANT:Fire water pumping stations - Water network

 

Fire water pumping stations

     Two firewater tanks of 2300-m3 each shall be provided.

 -         They shall be of a semi-buried and concrete type and shall not be more than 0.5 m above ground level Civil works general design"

 - Two firewater-pumping houses shall be provided and located in the vicinity of the above water tanks.

     Location of both tanks and pumping houses will be selected so as:

      - to minimize the distance from the fuel storage the area as that latter is representative of the most important potential need but keeping in mind an optimum distance shall secure the reliable operation of the pumping station in any case of fire,

    - to allow safe access to firemen and fire vehicles in any case of fire (in connection with suitable road layout),

 -   to evenly cover the whole plant as regards the water pressure distribution throughout the piping.

     Each pumping house shall be equipped as follows:

 -         one AC-driven jockey pump, which shall maintain the network to its nominal operating pressure (7 bar).

 -         It shall start when the pressure drops to about 90 % of its nominal operating pressure and stops when the pressure reaches about 110 % of its nominal operating pressure.

 -         one AC-driven pump of adequate size as per NFPA standard but not less than 350 m3/h at 10 bar, which shall start when the pressure drops to about 80 % of its nominal operating pressure.

 -        Shut-off pressure shall not exceed 140 % of the rated head of the pump at the rated capacity.

         - one diesel-engine driven pump of adequate size as per NFPA standard but not less than 350 m3/h at 10 bar, which shall start when the pressure drops about to 60 % of its nominal operating pressure.

 Shut-off pressure shall be as above.

    The final setting of the above water pressure thresholds shall be made in consideration of the two stations working together and discharging on the same interconnected water loop.

     For example, THE second AC-driven pump shall start before the first diesel-engine drove pump.
    The pumps shall discharge on a manifold connected to the hereafter-defined water network.
     The pumping stations shall also house a foam generating system, as hereafter mentioned.
   The pumping stations shall be designed to work fully unattended. They shall be monitored from the support system management console located in the main control room and in the fire-fighting center.

        Water network

     Looped water the network shall surround the whole Power Plant with hydrants spread out and especially in the vicinity of the major equipment such as fuel storage, fuel treatment, water treatment, and power generation buildings.

   The following functions are intended for this network:
        - External cooling of the tank shells in case of fire by means of a deluge system.   The system shall only be manually actuated (opening of the relevant valve),
        - supply of water to the foam generation systems,
        - feeding of deluge system of transformers and cable galleries,
        - supply of water to the fuse plug water spray system,
-         Supply of water to the hydrants network as well as the feeding of fire trucks.

     Each hydrant shall be supplied with its own hose box, or cabinet.

     An indoor fire fighting water network is intended to be used in the buildings with solid hose racks at a pressure of about 3 bars. It shall be fed by the external fire fighting water network, through a pressure reducer.

     Semi-rigid reeled the hose on handy swirling racks, fitted with the hose ready and easy to use, shall be provided.

     For the warehouse, a water deluge system fuse plug type shall be provided.