Deluge systems as a fire safety design parameter

This study is part of the project Documentation of active fire fighting systems as a fire safety design parameter. The project covers both experimental- and theoretical studies of deluge systems used in offshore platform configurations. This report submits the experimental results from the medium scale experiment. The results are not evaluated towards practical consideration, but it is planned to evaluate the results by use of real scale experiments at the end of the project.

In, general design of deluge system focus on safe and reliable water supply to every single nozzle, while this work is focusing on the interaction of water and flames. The nozzles are characterised by geometrical factors like spray pattern, spray angle, and by exit velocity, capacity and area coverage. In this report, sets of footprint for each nozzle at every water pressure used in these experimental series are presented.

The experimental series are carried out by SINTEF Civil and Environmental Engineering – Norwegian Fire Research Laboratory (SINTEF NBL).

The aim of the project

The overall aim of the project is to establish the basis of predictive methods for the abilities of the active systems in terms of fire fighting effect in case of an accident. Such predictive methods are giving the oil companies better opportunities to reach optimum design of the installations in terms of cost, productivity and safety. The methods result in higher degree of freedom for the designers.

The project shall establish ways to prove and quantify the effect from deluge fire suppression systems on heat load from design fire scenarios (real fire load). Real fire load can be used for design of passive fire protection and local protection of vessels of offshore installations. The effect of active systems shall be measured in quantitative terms. A test rig for accurate measurement of characteristics of fires subjected to fire suppression systems was constructed and instrumented in the large test hall at SINTEF NBL.

Medium scale experiment

The experimental results from the medium scale experiment. The test series focuses on the interaction between the deluge water and flames in an 8m high 3m diameter test rig.

A total amount of 54 tests were carried out with variation of nozzles, fire sizes, water pressures, ventilation conditions, extinguishing media and nozzle elevations. Five different nozzles were tested in opposed flow to flames from 5MW to 8MW gas fires.

The results are measured in terms of reduction of heat release rate from chemical reactions. Also changes in thermal radiation heat load to construction and gas temperatures are included in the measurements.

The efficiency of increasing water application rate is strongly dependent on the nozzle characteristic and increase in water application rate is most efficient when dealing with low ventilated fires. Possible factors for the resulting reduction of heat release rate include droplet size, application pressure, volume fraction of water in the exhaust gas, nozzle footprint and nozzle elevation.

Contact us:
E-mail:
Phone: (+47) 73 59 10 78
Fax: (+47) 73 59 10 44