Page 259 - Introduction to Marine Engineering
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Fire  fighting  and  safety  235






            Nozzle
                                    Acid bottle cage
                                     Acid bottle
                                    -•—Steel container



         internal pipe




















         Figure  13.4 Soda-acid extinguisher



         The  extinguisher  is then  inverted  for  the  two liquids to  mix. Carbon
         dioxide is produced by the  reaction  which pressurises  the container  and
         forces  out  the  foam.


         Foam  extinguisher—mechanical
         The  outer  container  in  this  case  is  filled  with  water.  The  central
         container  holds a  carbon  dioxide  charge  and  a  foam  solution  (Figure
         13.5(b)). A  plunger mechanism  with a safety  guard is located  above  the
         central container.  When the  plunger  is depressed the  carbon  dioxide is
         released and the foam  solution and water mix. They are then forced out
         through  a  special  nozzle  which  creates  the  mechanical  foam.  This
         extinguisher  has an internal pipe and  is operated  upright.
           Foam extinguishers are  used on Class B fires and  will be located in the
         vicinity  of  flammable  liquids.
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