Water Mist Fire Tests For Class 2 & 3 Engine Rooms
FACTORY MUTUAL RESEARCH CORP NORWOOD MA
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Twenty three fire tests were conducted to determine the ability of typical current water mist technologies to extinguish fires specified in the International Maritime Organization IMO fire test procedure for Class 2 and Class 3 engine rooms. Sixteen of the 23 tests used fire scenarios specified in the IMO test procedure. They were conducted using nozzles installed at a 5 m height and 1.5 m spacing in a large test facility 2800 m2 area and 18 m height in which no additional enclosure surrounded the nozzles. Two types of mist heads were tested a low pressure nozzle operating between 1.2 MPa and 1.5 MPa with flow per head between 12.0 and 13.4 lpm and a high pressure mist head consisting of 7 nozzles operating at 6.9 MPa flowing 5.3 lpm per head. The fire tests selected from the IMO procedure included 6 MW diesel spray fires on top of the IMO engine mockup, a shielded 6 MW diesel spray fire adjacent to the mock-up, a 1 MW shielded diesel spray fire adjacent to the mock-up, and a wood crib within a 2 m2 pan filled with heptane. The results of this test program indicate that current water mist technology, as represented by the two systems used in the test program, is unlikely to be capable of extinguishing test fires in the IMO fire test protocol for Class m engine rooms. In tests with 36 or one hundred low pressure nozzles, fires were not significantly affected by the water mist. Similarly, when 36 or 90 high pressure mist heads were installed, extinguishment also did not occur. To further investigate mist system capabilities, a ceiling was then placed over the nozzles covering an area of 188 m2. Using 90 high pressure nozzles, the test fires were not extinguished. A 940 m3 enclosure was then formed by dropping tarpaulins to the floor from the ceiling. A 4 m2 vent was placed in the wall. With the 90 high pressure nozzles, the 6 MW spray fire on top of the mock-up was extinguished.
- Safety Engineering