• Fire Science and Engineering
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• v.10 no.3
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• pp.51-57
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• 1996

반응시간지수(Response Rime Index : RTI)를 사용하여 스프링클러의 열응답(thermal response) 특성을 분류할 수 있다. 반응시간지수는 plunge test에서 균일한 고온의 공기속도의 제곱근과 스프링클러 열감지부의 시정수(time constant)의 곱으로 나타낼 수 있다. 고온의 주위 공기온도에서 스프링클러가 작동하는 시간을 측정하므로서 열감지부의 시정수를 계산할 수 있다. 스프링클러의 RTI가 시정수에 비하여 실험조건에 따른 변화 폭이 적으므로 실제 화재시의 스프링클러 자동시간을 예측하는데에는 RTI가 사용된다. 스프링클러의 작동시간 예측을 위해서는 RTI값과 스프링클러 열감지부 주위의 유속이 필요하며, 유속은 화재의 발열량과 스프링클러가 설치된 구획의 높이로부터 실험식으로 결정된다. 따라서 Plunge test를 이용하여 얻은 스프링클러 열감지부의 기본자료로부터 실화재시의 스프링클러 작동시간을 예측하게 되며, ZONE 모델과 같은 화재 simulation 프로그램과 같이 사용된다면 스프링클러 작동시의 연층의 높이도 예측 가능하게 된다.

• Fire Science and Engineering
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• v.34 no.3
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• pp.35-42
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• 2020

The accurate prediction of fire detector activation time is required to ensure the reliability of fire modeling during the safety assessment of performance-based fire safety design. The main objective of this study is to determine the activation temperature and the response time index (RTI) of a fixed heat detector, which are the main input factors of a fixed-temperature heat detector applied to the fire dynamics simulator (FDS), a typical fire model. Therefore, a fire detector evaluator, which is a fire detector experimental apparatus, was applied, and 10 types of domestic fixed-temperature heat detectors were selected through a product recognition survey. It was found that there were significant differences in the activation temperature and RTI among the detectors. Additionally, the detector activation time of the FDS with the measured DB can be predicted more accurately. Finally, the DB of the activation temperature and RTI of the fixed-temperature heat detectors with reliability was provided.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 1996.11a
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• pp.68-71
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• 1996

The thermal response of sprinkler is characterized by the response time index(RTI). The RTI represents the product of the thermal time constant for the heat responsive element of a sprinkler and the square root of the hot air velocity at plunge test. A plunge test is adapted for measuring RTI, wherein a sprinkler is suddenly immersed in the steady flow in the test section of a hot air tunnel. The method of measurements of the response parameters is presented.

• The Journal of Engineering Geology
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• v.26 no.2
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• pp.235-250
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• 2016

In Korea, 70% of the annual rainfall falls in summer, and the number of days of extreme rainfall (over 200 mm) is increasing over time. Because rainfall is the most important trigger of landslides, it is necessary to decide a rainfall threshold for landslide warning and to develop a landslide warning model. This study selected 12 study areas that contained landslides with exactly known triggering times and locations, and also rainfall data. The feasibility of applying a Rainfall Triggering Index (RTI) to Korea is analyzed, and three RTI models that consider different time units for rainfall intensity are compared. The analyses show that the 60-minute RTI model failed to predict landslides in three of the study areas, while both the 30- and 10-minute RTI models gave successful predictions for all of the study areas. Each RTI model showed different mean response times to landslide warning: 4.04 hours in the 60-minute RTI model, 6.08 hours in the 30-minute RTI model, and 9.15 hours in the 10-minute RTI model. Longer response times to landslides were possible using models that considered rainfall intensity for shorter periods of time. Considering the large variations in rainfall intensity that may occur within short periods in Korea, it is possible to increase the accuracy of prediction, and thereby improve the early warning of landslides, using a RTI model that considers rainfall intensity for periods of less than 1 hour.

• Journal of the Korean Society of Safety
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• v.13 no.4
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• pp.59-70
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• 1998

In this study, response time index(RTI) of standard and quick response type sprinkler head are measured and compared through ramp and plunge test in heated wind tunnel. Also discharge rate and water distribution, actual delivered density(ADD), fire test with wood cribs are performed to compare the fire suppression capability and the operation time and temperature between standard and quick response type sprinkler head.

• Journal of the Korean Society of Safety
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• v.32 no.2
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• pp.46-51
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• 2017

This paper presents classification of domestic fire detector using response time index. Response time is measured using fire detector distributed in Korea, and the response time index is estimated. Plunge test prescribed by FM is conducted to measure response time of fire detector. The detector used to test is fixed temperature type(thermistor and bimetal type) and rate of rise temperature type(thermistor and pneumatic type). The nominal operation temperature of fixed temperature type detector is $70^{\circ}C$ and rate of rise temperature is $15^{\circ}C/min$. The fixed temperature type is measured 7 products, and the rate of rise temperature type is measured 5 products. The results show that in case of fixed temperature type(thermistor) is classified "Quick" or "Standard" and fixed temperature type(bimetal) is not classified. The rate of rise temperature type(thermistor) is classified "Fast" or "Ultra Fast" and the rate of rise temperature type(pneumatic) is classified "Very Fast" or "Ultra Fast". The pneumatic type shows more fast response than thermistor type. Also these results indicate the fixed temperature type(bimetal) is not suitable for early stage fire detection.

• Fire Science and Engineering
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• v.7 no.1
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• pp.11-16
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• 1993

Fixed temperature heat detectors that respond to the heat generated in fire plume and alarm when the temperature reaches a specified point, give a great influences to the loss of life and property according to their reaction sensitivity. In this study, hot wind tunnel tests and compartment fire experiments were performed to investigate the response time and temperature of fixed temperature heat detector. As a result, simple equations were derived which can be predicted the response time and temperature of the fixed temperature heat detector for the ramp type fire. Also other useful data, such as the effective temperature, time constant, response time index(RTI) were obtained.

• Fire Science and Engineering
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• v.34 no.4
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• pp.45-51
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• 2020

The aim of this study is to investigate the gas temperature and velocity during sprinkler activation considering the fire growth scenario based on the thermal response model of the sprinkler. The fire source is assumed to have time square fire growth scenarios with a maximum heat release rate of 3 MW. Eight types of standard and fast-response sprinkler heads with an operating temperature range of 65-105 ℃ and a response time index range of 25-171 m^1/2s^1/2 were adopted. The temperature difference between the gas stream and the sensing element of the sprinkler head decreased as the fire growth slowed down, and the RTI value decreased. The overall gas temperature and velocity conditions predicted using the FDS model at sprinkler activation were in reasonable agreement with those of standard test conditions of the sprinkler head response. However, the sprinkler head could be activated at lower limits of gas temperature and velocity under the current test conditions for a slowly growing fire scenario.

• Fire Science and Engineering
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• v.26 no.3
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• pp.79-84
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• 2012

In this study thermal characteristics of heat-responsive element considering conduction, convection and rate of change of element using Response Time Index (RTI) applied to sensitivity test of sprinkler head at home and aborad are theoretically investigated. Analytic solution of temperature distributions with radial direction and time is obtained form energy transport equations, non-homogeneous 2th order partial differential equation, applying to constant wall temperature and symmetric condition in order to analyze thermal characteristics of heat-responsive element for circular cylindrical geometry. Base on the results, the analytic method of this study is fundamental data to practical use for sensitivity test of sprinkler head and design of heat-responsive element.

• Fire Science and Engineering
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• v.10 no.4
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• pp.13-18
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• 1996

A general description of sprinkler activation time in compartment-fire-generated smoke layers is made. For calculation of the time hot layer temperature is obtained from two-layer zonal model and time constant of sprinkler is measured. Upper-layer thickness at the instant of sprinkler activation is also presented with changes of opening area. The output of the present study provide inputs for the interaction modeling of sprinkler spray and compartment fire environment, which simulates fire suppression phenomena. Futhermore, experiments are performed in mock-up with gasoline pool fire in order to evaluate the reliability of the model.