The Response Time of Different SprinklerGlass Bulbs in a Residential Room FireScenario

• The response time of fire sprinklers is essential for their performance,especially in applications where life safety protection is desired. The earlier the sprin-kler activates, the smaller the size of the fire. Most commercial residential sprinklersare fitted with 3 mm, 68C glass bulbs. However, thinner sprinkler glass bulbs withlower operating temperatures are available. The aim of this study was to determinethe response time—and the corresponding heat release rate—of different glass bulbsin a residential room fire scenario. A series of tests were conducted inside a compart-ment measuring 3.66 m by 3.66 m having a ceiling height of 2.5 m. The compartmentwas either enclosed or had two walls removed to provide a more ventilated scenario.A propane gas burner was positioned at one of the corners. The mass flow rate ofthe gas was controlled such that either ‘slow’, ‘medium’ or ‘fast’ fire growth rate sce-narios were simulated. In each test, nine Response Time Index (RTI) and operatingtemperature combinations were tested. Each test was replicated three times. In addi-tion, two commercial fire detectors were tested. The results show that the fire is con-siderably smaller upon activation with a combination of a low RTI and a lowoperating temperature, as compared to the 3 mm, 68C glass bulb typically used forresidential sprinklers. The operating temperature proved to have a larger impact onthe results than the RTI. The heat from the fire was typically detected by the firedetectors prior to the activation of the sprinkler glass bulbs, especially for the ‘slow’and ‘medium’ fire growth rate scenarios.

Nyckelord

Sprinkler glass bulbs

Response Time Index (RTI)

Operating temperature

Fire detectors

Response time

Residential room fire scenario

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