Fire Smoke Detector Research Articles

Experimental Study on Particle Size Distribution Characteristics of Aerosol for Fire Detection

Current optical fire smoke detectors use scattering light intensity as an indicator of smoke concentration and trigger fire alarms when the intensity exceeds a threshold value. However, such detectors are prone to false alarms caused by non-fire aerosols since both fire smokes and non-fire aerosols scatter light. Thus, in order to reduce false alarms caused by non-fire aerosols such as dust and water vapor, fire detectors must be capable of distinguishing fire smoke from non-fire aerosols. Since the light scattering signals depend on the particle size information of aerosols, it is essential to study and characterize the particle size distribution of fire smoke and non-fire aerosols for differentiating them. In this paper, a comprehensive aerosol experimental platform is built to measure the particle size distribution of various typical fire smokes and non-fire aerosols. Through the conducted experiments, we note that there are significant differences in the particle size distributions of typical fire smokes and non-fire aerosols, with a boundary of about 1μm. The experimental results provide fundamental data support of the particle size distribution for developing a better fire detector that accurately identifies smoke.

Dual-Wavelength Smoke Detector Measuring Both Light Scattering and Extinction to Reduce False Alarms

Existing fire smoke detectors use the intensity of scattering light or the light extinction coefficient as the indicator of fire smoke to trigger fire alarms. However, false fire alarms could be triggered by dust and water fog. Achieving reliable early fire detection with minimal false alarms is a challenge. Based on the Mie scattering theory of spherical particles, it is derived that the ratio of scattering intensity and the ratio of optical extinction of two incident lights with different wavelengths only depends on the intrinsic properties of the aerosol (the average particle size and refractive index). This paper then presents an improved dual-wavelength smoke detection by measuring scattering light and extinction simultaneously to reduce false alarms. Simulations and verification with test fires of European Standard EN 54 were performed, demonstrating that fires can be distinguished from nuisance sources without complicated calculations. These results indicate that the improved detection system can be applied for smoke monitoring and fire protection.

Application Assessment of Electrical Cables during Smoldering and Flaming Combustion

Electrical cables are a potential source of ignition and fire hazards in various types of buildings and industrial installations, as well as in all modes of transportation, including aircraft. Fires in buildings pose the greatest threat to human life and health. The composition of thermal degradation products depends mainly on the type of combustible materials and the type of combustion process—flaming or smoldering. The purpose of this paper was to determine, based on experimental studies, the effects of flaming and smoldering combustion on the response times of fire smoke detectors. In addition, the concentrations of fire gases formed in the process of duct combustion, including CO, SO2, NO2, NO, HCN, HCl, HBr and HF, were measured using an FTIR spectrometer. The results presented confirm the significant effect of the way the cable samples burned on detector tripping time. The highest concentration of smoke (Y) in the test chamber was obtained during flame combustion. It was further found that the characteristics of the cable insulation material used, such as the type of PVC, had a significant effect on the toxicity of the emitted gases. The largest amounts of toxic gases were emitted during the smoldering combustion of a cable with a plasticized PVC sheath.

Design Build a Smarthome Prototype on House Type 36 with IOT-Based Smartphone Control

Technology's rapid development certainly benefits the people who use it. One example of technology today is the application of technology systems at home, with significant problems for homeowners, such as fire and theft. Incidents like this can result in losses for homeowners in terms of material and even to the point of causing loss of life. With such problems, it is necessary to have a system that can monitor these events. One solution to this problem is designing a smart home or smart home. The smart home or smart home is a term used to refer to a modern dwelling with remote control. The intelligent home prototype design for the type 36 house is an innovative home appliance design that uses automatic commands controlled by the homeowner's smartphone. This intelligent home prototype design research aims to be a reference for today's modern homes for the community, especially for type 36 houses. In this study, the five systems studied were automatic light control, automatic doors, gas leak detectors, fire smoke detectors, and room temperature detectors. Excess Commands from the prototype system are carried out using SMS from the GSM SIM900 module connected to the smartphone. The results of this study are an intelligent home prototype in a type 36 house that can be controlled via a smartphone. It is hoped that this automatic system device can make it easier for the community to carry out supervision at home to prevent unwanted things and help ease work so that people are more productive in carrying out other essential activities and provide a sense of security and comfort from danger in the house where they live. Beloved family.

Optimizing the process of fire detection in warehouses considering the type and location of fire detectors

An integral condition for avoiding damage due to fires in warehouses, or at least minimizing them, is the early detection of fires using fire protection systems, as well as its timely localization. Depending on which fire detectors are selected to protect the relevant premises and where they are installed, the time of operation of all elements of automatic control systems in case of a fire will depend. The review of literary data revealed that at present there is no comprehensive approach to choosing the optimal placement in warehouses. In addition, the optimal placement of fire detectors within the room, taking into consideration the type of fire load, has not been sufficiently studied. Therefore, the purpose of the current study is to establish the dependence of the time of operation of different types of fire detectors on the type of combustible material, namely its mass burnout rate, distance, and height of placement of detectors from a potential fire site. This paper reports a procedure for conducting an experimental study to identify the appropriate dependence for warehouses. The results of the experiments showed that the most effective in warehouses are targeted fire smoke detectors and aspiration systems. Based on the results of a complete factor experiment, nonlinear empirical dependences to determine the time of operation of smoke fire detectors on the above factors were built. The resulting empirical dependences make it possible to choose fire detectors and optimally place them within a room. The average error in these dependences when compared with the experimental data is 6.9 %. The use of the derived dependences makes it possible to reduce the time of operation of fire detectors by 14 s in comparison with their placement in accordance with building codes

Development of a Fire Smoke Detector that Satisfies the UL 268 (7th Edition) Fire Sensitivity Tests

In this study, we developed a multi-sensor fire detector that satisfies the revised requirements of the cooking nuisance test, polyurethane foam fire test, and polyurethane foam smoldering smoke test of UL 268, and the special program, UL 268 (7th edition), at the Underwriters Laboratories (UL) headquarters in Northbrook, Illinois, United States. The fire detection algorithm was confirmed using the "Research Preliminary Test" program. Our fire detector was evaluated in a dark room with a smoke detector consisting of photoelectric, carbon monoxide, and ionization sensors, and was mounted on a board. In addition, the upper case of the detector is designed to have sufficient space on its top and side surfaces to allow the flow of air and combustion gases. As a result, in the polyurethane foam fire test, the detector triggered an alarm (within 3 min) before the smoke concentration reached 5%/ft (after 3-4 min); thus, satisfying the requirements of the UL 268 polyurethane foam fire test. In the polyurethane foam smoldering smoke test, the detector was operated for 22-26 min before the smoke concentration reached 12%/ft (after 26 min), thus satisfying the requirements of the UL 268 polyurethane foam smoldering smoke test. Lastly, in the cooking nuisance test, the detector was operated for 16-18 min before the smoke concentration reached 1.5%/ft (after 16 min), thus satisfying the requirements of the UL 268 cooking nuisance test. It can be concluded that the results of this study will be useful for the developers of similar products who want to obtain UL certification in the future.

Research on the aerosol identification method for the fire smoke detection in aircraft cargo compartment

The false alarms produced by non-fire aerosols and low sensitivity to black smokes are two types of critical issues for optical fire smoke detectors, especially in the field of aviation. Dusts and droplets are considered as the typical nuisance aerosols in aircraft cargo compartment. In this paper, the effects of wavelength, polarization of light source and scattering angle were analyzed by numerical calculation and experimental measurement. The trend differentiation method based on asymmetry ratio (45/135) is proposed based on the numerical results. Detector prototypes with LEDs or LDs were developed for experimental verification analysis. Experimental results show that by using light sources at 405 nm with vertical polarization and 850 nm with horizontal polarization, the nuisance aerosols can be separated from fire smokes according to the relative size of asymmetry ratios, and furthermore white and black smokes also can be differentiated according to the size of asymmetry ratios. Therefore, the balanced response sensitivity to white and black smokes can be realized by adjusting the alarm response threshold accordingly.

An optical fire detector with enhanced response sensitivities for black smoke based on the polarized light scattering

Optical fire smoke detectors trigger the fire alarms when the scattering light intensity exceeds a preset threshold. Current optical detectors usually takes a long time or even fail to trigger a fire alarm for black smoke due to the strong absorption and weak scattering efficiency. A fire smoke sensor with dual polarized channels is proposed to adjust the response sensitivities to both white and black smoke. The white and black smoke can be discriminated by the polarization degree, and thus the response sensitivity can be adjusted by a correction factor. A prototype sensor is set up and tested by monodisperse aerosols with a maximum error of 10.1%. According to the experimental results, the prototype sensor could correctly differentiate white smoke and black smoke based on polarization degree, and the fire alarm for black smoke can be triggered as fast as for white smoke.

A Sauter mean diameter sensor for fire smoke detection

Existing fire smoke detectors utilize the intensity of scattering light as the indicator of fire smokes to trigger fire alarms, but a false fire alarm would be triggered by non-fire aerosols due to their similar concentration characteristics. According to the measurement results of our experiments and related works, the Sauter mean diameters of fire smokes are usually smaller than those of non-fire aerosols. Instead of the smoke concentration detector, a new type of Sauter mean diameter sensor is developed based on dual wavelength technology for fire detection. In order to measure the aerosol samples with different particle size distribution and refractive indices, an extra correction channel is added to reduce the measurement error from 39.1% to 7.61%. The sensor is calibrated by the DEHS (Di-Ethyl-Hexyl-Sebacat) aerosols in different sizes and tested by several typical fire smokes and non-fire aerosols, the results show that the sensor can timely trigger a fire alarm to fire smokes and avoid the false alarm caused by non-fire aerosols. With simple mechanical structure and high accuracy, this sensor improves the performance of optical fire smoke detector with high sensitivity, low-cost and unique ability to resist the false alarms caused by non-fire aerosols.

A Video Based Fire Smoke Detection Using Robust AdaBoost.

This work considers using camera sensors to detect fire smoke. Static features including texture, wavelet, color, edge orientation histogram, irregularity, and dynamic features including motion direction, change of motion direction and motion speed, are extracted from fire smoke to train and test with different combinations. A robust AdaBoost (RAB) classifier is proposed to improve training and classification accuracy. Extensive experiments on well known challenging datasets and application for fire smoke detection demonstrate that the proposed fire smoke detector leads to a satisfactory performance.

Eliminating the effects of refractive indices for both white smokes and black smokes in optical fire detector

Existing optical fire smoke detectors would take more time or even fail to trigger alarms of black smokes because the optical scattering efficiencies of black smokes are much lower than those of white smokes. In this paper, we design an optical fire smoke detector with consistent response to white smokes and black smokes based on dual-wavelength technology and multiple scattering signals. The proposed detector utilizes the incident lights of dual wavelengths to measure the surface area concentration and volume concentration of fire smokes respectively. The particle size distribution of the smokes can be estimated by these concentrations. The refractive indices are deduced by the third scattering signal and more observing angles are helpful to reduce the measurement errors. As a result, a 4-channel detector [140°–950nm, 45°–950nm, 140°–450nm, 45°–450nm] is developed, which can accurately measure the concentrations of both smoldering cotton (white smoke) and open fire of polyurethane (black smoke).

A New Calculation Model of Detection Time for Heat Detector in Long and Narrow Space

Abstract Fire detector plays an important role in ship fire safety system. Usually, there are two types of fire detectors including fire smoke detector and heat detector, which are widely used in exit passageway, corridor, ladderway, and other long and narrow spaces in ship. Due to the smoke plume characteristics in these limited spaces are different to that of free plume in open place, the detection time calculating model of heat detector for these two different conditions are consequently different. This work is to develop a new detection time calculating model based on the fire plume rules including characteristics of temperature and velocity of fire smoke distributing in long and narrow spaces. Numeric method for calculating detection time is also presented. Finally, some calculations and analysis for a given fire scenario are performed. The numeric results are compared with that of the existing detection time calculating model based on free plume theory, which demonstrate the applicability of the model proposed in this article.

Experimental Study on the Testing Environment Improvement of Fire Smoke Detectors

Abstract To simulate the test smoke for fire smoke detectors, the bypass setting of aerosol generator is currently adjusted to the particle size of 0.75 μm according to the standard of EN 54-7 of China. It leads to the single test environment of fire smoke detectors. In this paper, the improvement of aerosol generator is presented. It makes the aerosol flow which has different particle size characteristics can be generated by aerosol generator and be installed several bypass flows according to the principle of aerosol generator. By the way, the particle size distribution and particle size characteristics of aerosol flow can be obtained after measuring the quality of aerosol flow which is collected under different bypass flows by Berner Impactor. So the different type of test smoke for fire smoke detectors can be obtained by aerosol generator. And then, the distribution characteristics of aerosol flow can be obtained in testing tubes (EN54-5/7c) of fire smoke detectors. Finally, the improved test environment of fire smoke detectors has realized the diversification of test environment. And the reliability of the test results has improved through this study.