ABSTRACT
Experiments are carried out to measure the effect of deluge systems at large scale. The tests were performed with the release of a gaseous propane jet, originating from a nozzle, ignited and impinging at sonic speed, at a rate of 0.9 kg/s, into a test rig consisting of cylindrical objects (oil barrels) [1]. Two different configurations of deluge systems were tested, with High-velocity and Medium-velocity nozzles, typically used in offshore oil-and gas production platforms. The nozzles were of the same type as used in an earlier test series at SINTEF, carried out indoor in a large test hall [6].
The tests were run for two minutes without deluge. Then deluge was applied, first at a low water rate, increased at steps of approximately two minutes, until quasi-stationary conditions were obtained. Water application rates from 8, 5 to 21 l/m2 min were tested.
Measurements of temperature by thermocouples between the objects and inside some of the objects and heat flux density at a distance from the test rig were performed.
The radiation to the ambient (external) and between (internal) the objects was reduced by deluge, for both High-velocity and Medium-velocity nozzles.
The radiation to the ambient and between objects decreased with increased water application rate.
The reduction of radiation was in the order of 20-30 % for the highest water application rates.
At some positions, close to the hit-point of the jet fire, no reduction of radiation between objects was registered.
At positions away from the hit-point, the radiation between the objects was significantly reduced. At the highest water application rate with both nozzles type, the flames were almost not visible at short periods of time. The jet fire was however not extinguished in these situations.
The results of the tests form a data base for the distribution of temperatures and heat load from a jet fire, and the effect of deluge systems at different water application rates. The data base is also a source for verification of computer models for these phenomena.
Keywords: Jet fire, Deluge system, Fire mitigation.
