Ionization Smoke Detectors Research Articles

The Influence of Air Humidity on the Output Signal from an Ionization Smoke Detector in the Presence of Soot Nanoparticles

In 2019, the European Committee for Standardization (CEN) initiated work on the preparation of a strategy for air quality monitoring at workplaces. The aim was to determine the concentrations of nano-objects and their aggregates and agglomerates (NOAA) by means of direct measurements using low-cost sensors. There is a growing need for low-cost devices that can continuously monitor the concentrations of nanoparticles, and that can be installed where nanoparticles are used or created spontaneously. In search of such a device, in this study, a smoke detector with an ionization sensor was tested. The aim of the research was to investigate the response of the analog output signal with respect to changes in environmental parameters such as the relative humidity of air. The research was conducted in controlled laboratory conditions, and the results confirmed that an ionization detector could be used to measure the concentrations of nanoaerosols. The modified smoke detector detected soot particles smaller than 100 nm. The linear regression line was calculated for the relative humidity dataset and had a slope coefficient of −1.214 × 10−4; thus, the value of the output signal was constant during the experiment. The dependence on air temperature was approximated by a second-degree curve, with a slope coefficient of −8.113 × 10−2. Air humidity affected aerosol concentrations, which may be related to surface modification of nanoparticles.

Evaluation of Empirical Evidence Against Zone Models for Smoke Detector Activation Prediction

A series of experiments were conducted in a large room to generate data to assess the accuracy of computer fire model predictions of detector activation time. A comparison between experimental measurements and zone model predictions of the detector activation in the Consolidated Fire and Smoke Transport model (CFAST) version 7.4.3 were made. The experimental room was 11.0 m by 7.3 m by 3.7 m high with a single opening 2.44 m high and 1.83 m wide centered in a short wall. Two ceiling configurations were examined, a flat ceiling and a flat ceiling with two 0.30 m wide and 0.30 m deep solid beams. The fire source was a gaseous fuel burner fed with different mixtures of propane and propene that produced soot yields ranging from 0.010 gsoot/gfuel to 0.072 gsoot/gfuel and a fuel flow ramp time that ranged from 30 s to 1800 s. The heat release rate profile reached a nominal maximum value of 30 kW. The activations of two different models of photoelectric smoke detectors and a single ionization smoke detector, each with a range of alarm set points and installed at various locations on the ceiling, were recorded. Predictions of the various smoke detector activation times were made in CFAST with the temperature approximation method, and a fixed smoke detector concentration method for photoelectric detector activations. Predictions with the smoke detection method were better than the temperature approximation method over the range of fire scenarios examined. Predictions of smooth ceiling experiments were generally better than the beamed ceiling experiments.

IoT-Based Fire Safety System Using MQTT Communication Protocol

Fire can be made useful for various purposes. However, uncontrollable fire may result in property damage and human death. The major factor of fire deaths is due to excessive smoke inhalation. Therefore, early detection of fire is crucial in fire detection systems. The conventional fire detection system does not come with a false alarm prevention system. Besides, the system is unable to tell the exact location of the fire. In this project, an Internet of Things (IoT) based fire safety system is developed to overcome these problems. The proposed system consists of three major parts which are the detector, processing unit and surveillance. The detector unit is an integration of ESP32, carbon monoxide sensor, ionization smoke detector, buzzer, temperature and humidity sensor. As the processing unit, Raspberry Pi is used to run the Node-RED application, which processes the data and performs monitoring. The communication between the detector and processing unit is based on the Message Queuing Telemetry Transport (MQTT) protocol. A surveillance unit is where a camera is installed to monitor the condition of the surrounding. The response of the system is based upon the sensor’s values or the user’s response. Once the fire breakout is confirmed, the system will immediately sound the alarm, and Global Positioning System (GPS) coordinates and floor plan of the accommodation will send to the nearby fire station. The floor plan is developed to track the exact location of the fire. Experiments are carried out on the proposed fire safety system, and encouraging results are produced.

Reliability Assessment of Photoelectric Smoke Detector, Ionization Smoke Detector and a Fire Alarm Control Panel with Both Detectors AS Notification Device

Notification device like smoke detectors are critical and important part of a Fire Alarm Control Panel (FACP). Popularly used smoke alarms in commercial establishments in India are photoelectric smoke alarms (PESD) and ionization smoke alarms (ISD). In this study reliability assessments of PESD with Integrated Circuit (IC) – MC145010 and ISD with IC – MC145017 have been carried out on the basis of reliabilities of their respective electronic components. The cases considered are: (I) Failure rates of all components are equal and constant over time (II) Failure rates of all components are equal and follow Weibull distribution and (III) Failure rates of all components are different. To determine failure rates of 9 volt battery of both detectors additional assumptions taken are, (a) battery life is 10 years with constant failure rate, (b) battery life follows Weibull distribution. In this paper the reliability and failure rate of two types of smoke alarms have been calculated based on failure rates of their electronic parts like resistors, capacitors, Integrated Circuits etc. These failure rates have been subsequently used for reliability assessment of a non-addressable FACP containing four PESDs and four ISDs as notification device. A comparison of failure rates was also performed on the basis of two quality factors of electronic components – military specific and lower than military specific. Mean Time To Failure (MTTF) of PESD and ISD have been calculated in all the cases. Subsequently, MTTF values obtained in case III were used to approximate failure rates for case I case II.

Influence of high altitude on the burning behaviour of typical combustibles and the related responses of smoke detectors in compartments.

The effect of altitude on typical combustible burning and related smoke detector response signals was investigated by comparison experiments at altitudes of 40 m and 3650 m based on EN54 standard tests. Point-type light scattering photoelectric smoke detectors and ionization smoke detectors were used for four kinds of EN54 fire tests, including two kinds of smouldering fires with wood (test fire no. 2 in EN54 standard or TF2) and cotton (TF3), and two kinds of flaming fires with polyurethane (TF4) and n-heptane (TF5). First, the influence of altitude or ambient pressure on mass loss for smouldering combustion (TF2 or TF3) was insignificant, while a significant decrease in the mass burning rate was found for flaming tests (TF4 and TF5) as reported in our previous studies. Second, for photoelectric smoke detectors in flaming fire tests, the effect of altitude was similar to that of the burning rate, whereas for the ionization smoke detectors, the response signal at high altitudes was shown to be ‘enhanced’ by the detection principle of the ionization chamber, leading to an even larger value than at normal altitude for smouldering conditions. Third, to provide a reference for smoke detector design in high-altitude areas, the differences between signal speed in rising and peak values at two locations are discussed. Also, relationship between ion chamber signals and smoke optical densities are presented by utilization of an ionization smoke detector and smoke concentration meter. Moreover, a hierarchical diagram is illustrated to provide a better understanding of the effects of altitude on combustible burning behaviour and the mechanisms of detector response.

화재모델링 예측성능 개선을 위한 이온화식 연기감지기의 장치물성 측정

성능위주 소방설계(PBD)의 과정에서 화재 및 피난모델링의 신뢰성을 확보하기 위해서는 화재감지기 모델의 높은 예측성능이 필수적으로 요구된다. 본 연구의 목적은 FDS와 같은 대와동모사(Large Eddy Simulation) 화재모델에 적용될 수 있는 연기감지기의 정확한 작동 개시시간을 예측하기 위한 수치적 입력정보를 측정하는 것이다. 이를 위해 화재감지기의 장치특성을 측정할 수 있는 FDE (Fire Detector Evaluator)를 제작하였으며, 이온화식 연기감지기에 대한 Heskestad 및 Cleary 모델의 입력변수가 측정되었다. 또한 일반적으로 사용되는 FDS의 기본 값과 측정된 값이 적용된 연기감지기의 작동 개시시간을 정량적으로 비교하였다. 주요 결과로써, 본 연구에서 검토된 이온화식 연기감지기의 장치 물성은 FDS에 적용된 기본 값과 매우 큰 차이를 보이고 있으며, 연기감지기 작동 개시시간이 최대 15분 이상 차이가 발생되었다. PBD의 신뢰성을 향상시키기 위하여 향후 연구에서는 보다 다양한 연기 및 열감지기의 장치물성에 대한 데이터베이스(DB)가 구축될 예정이다. The high prediction performance of fire detector models is essentially needed to assure the reliability of fire and evacuation modeling in the process of PBD (Performance Based fire safety Design). The main objective of the present study is to measure input information in order to predict the accurate activation time of smoke detector into a Large Eddy Simulation (LES) fire model such as FDS (Fire Dynamics Simulator). To end this, FDE (Fire Detector Evaluator) which can measure the device properties of detector was developed, and the input information of Heskestad and Cleary's models was measured for a ionization smoke detector. In addition, the activation times of smoke detectors predicted using default values into FDS and measured values in the present study were systematically compared. As a result, the device properties of smoke detector examined in the present study showed a significant difference compared to the default values used into FDS, which resulted in the considerable difference of up to 15 minutes or more in terms of the activation time of smoke detector. The database (DB) on device properties of various smoke and heat detectors will be built to improve the reliability of PBD in future studies.

Experimental Study On Response Sensitivity Of Smoke Detectors In High Flow Velocity

The objective of this work was to investigate preliminary design criteria of automatic fire alarm systems for some places with high flow velocity, e.g., exits of large underground car parks, the air outlets of large air conditioner etc. In addition, another main motivation of this research is to evaluate the appropriateness of Chinese standard which states that photoelectrics should be used in high flow locations. Two corresponding series of experiments were designed to analyze the response sensitivity of photoelectric and ionization smoke detectors under the conditions of different flow velocities in the Fire Emulator/Detector Evaluator (FE/DE), using smoldering cottons as the smoke source. The combining analysis of results of the two series of experiments indicated that generally speaking, ionization smoke detectors showed better response sensitivity than photoelectric smoke detectors in environments with high flow velocity. Preliminary analysis suggested that the influence of flow velocity on size distribution of the smoke particles generated is the main reason for the results.

Multivariate statistical process control for continuous monitoring of networked early warning fire detection (EWFD) systems

Sensor array networks provide much information concerning an environment if the data is adequately used. However, monitoring large networks of sensor arrays can be data intensive. Multivariate statistical process control (MSPC) methods allow monitoring of an entire system at a supervisory level. These methods are demonstrated for fire detection using the early warning fire detection (EWFD) system. The EWFD system comprised of four sensors that included photoelectric and ionization smoke detectors, as well as carbon monoxide and carbon dioxide sensors. Fourteen sensor arrays were distributed in 10 compartments and passageways throughout the ex-USS SHADWELL, the advanced damage control fire research platform of the Naval Research Laboratory. Data was collected for a series of smoldering and flaming fire sources as well as nuisance sources in different compartments over two decks. The network of sensor responses, location and temporal data are used to identify events, determine source location and monitor fire rate of growth. Hotelling’s statistic and the Q-statistic are employed initially for event detection. Subsequently, contribution plots are used to determine source location, rate of growth and to discriminate between actual fires and their byproducts in adjacent compartments. The response times of the MSPC method are compared to the commercial smoke detectors co-located with the EWFD systems. MSPC is shown to be an efficient method for continuous monitoring of EWFD systems.

EXPERIMENTAL STUDY ON THE SENSITIVITY AND NUISANCE IMMUNITY OF SMOKE DETECTORS

The objective of this work is to experimentally evaluate photoelectric and ionization smoke detectors with both the real fire scenario and nuisance alarm sources. This work is accomplished through a series of experiments in the Fire Emulator/Detector Evaluator (FE/DE), The results indicate that the sensitivity of smoke fire detectors is closely related to the characteristics of the smoke around them. The results also show that the scattering photoelectric smoke detector is much more sensitive to the simulated dust and the nuisance alarm would occur more easily. For the steam, the photoelectric detector would give a false alarm more easily in the cold winter than in the hot summer. Language: en

Investigation of an approach to fuel identification for non-flaming sources using light-scattering and ionization smoke detector response

Smoke detector performance depends on the detector and smoke characteristics as two decoupled phenomena. In this work, smoke properties on which various smoke detection principles are based were simultaneously measured in an enclosure using existing reference smoke detection systems. The measured smoke properties were scattered light intensity, response of measuring ionization chamber (MIC), obscuration, smoke particle density, and fuel mass loss. Data were collected for conventional fuels such as wood, paper, nylon, wool, polyurethane and PMMA, and also for unconventional fuels such as cooking oil and bread. The fuels were ranked nearly consistently, but in reverse order, based on ionization and light scattering reference detector responses. Discrimination of fuels using a simplified Mie scattering theory was examined. The analysis indicates that the Mie scattering coefficients are fuel-dependent and may be essentially unique to each fuel; however, an overall classification of different fuels using these coefficients may not be practical and requires more precise measurements.

New methods for reducing the number of false alarms in fire detection systems

In this paper, we present new methods of reducing the number of false alarms in smoke detectors and apply these methods to an ionization smoke detector. The detector is able to diagnose its working condition and its environment very precisely. When the detector's environment changes, the detector can automatically determine the cause, whether the change is fire-related or not. This is done by measuring the ionization current in two sensitivity ranges of the measurement chamber and analyzing the results with new algorithms. With the help of algorithms that use fuzzy logic, we can identify basically every potential problem an ionization detector can produce.

Detection Of Smoke: Full-Scale Tests With Flaming And Smouldering Fires

Full-scale fire tests are carried out to study the effectiveness of the various types of smoke detectors to provide an early warning of a fire. Both optical smoke detectors and ionization smoke detectors have been used. Alarm times are related to human tenability limits for toxic effects, visibility loss and heat stress. During smoldering fires it is only the optical detectors that provide satisfactory safety. With flaming fires the ionization detectors react before the optical ones. If a fire were started by a glowing cigarette, optical detectors are generally recommended. If not, the response time with these two types of detectors are so close that it is only in extreme cases that this difference between optical and ionization detectors would be critical in saving lives.

An Early Warning Effect™ Wallcovering System for Enhanced Fire Detection

This paper describes a new material that is designed to reduce fire hazard by increasing the probability of escape from potential fire conditions. Specifically, The BFGoodrich Company includes an Early Warning Effect™ (EWE) system for poly (vinyl chloride) coated wallcovering. When heated to approximately 150°C, the wallcoverings release an odorless, colorless vapor that activates ionization smoke detectors prior to the development of smoke and flames. As such, the wallcoverings provide an "earlier warning" of a fire hazard compared to conventional interior furnishing materials.

Smoke control in hospitals.

Full scale fire tests have been carried out in order to study the influence of different ventilating principles on the time point of fire detection and the smoke filling of a four-bed room. Using conventional mechanical ventilating systems as "smoke exhaust systems" the time difference left for evacuation of the fire room can be positively influenced. With the conventional ventilating system operating there is a significant difference between time points of detection of the ionization and optical smoke detectors, for both flaming and smoldering fire. Using the "low momentum displacement ventilation" this difference is reduced, resulting in possibilities for the ionization smoke detector to be optimized for both flaming and smoldering fires.

Smoke Detectors: Reducing Deaths and Injuries Due to Fire

The United States leads all nations in the incidence of deaths due to fire. In the past two decades significant technologic advances have resulted in the development of inexpensive and reliable smoke detectors. These detectors can provide early warning to allow sleeping residents easy exist when a fire ocfurs in the house. Currently, there are three major types of early warning devices: heat detectors, photoelectric smoke detectors, and ionization smoke detectors. Heat detectors sound an alarm in response to rapid increases in temperature and/or ambient temperatures above 135 F. Photoelectric smoke detectors are particularly effective for smoldering fires, because they are less influenced by the smaller particles of combustion emitted during household cooking or from automobile exhaust than are ionization smoke detectors. The ionization smoke detectors respond more quickly than photoelectric smoke detectors to fast burning fires and have been proved effective in sounding an early alarm in the vast majority of home fires. For best all-around fire protection, a home should have more than one type of detector. Detectors should be located on the ceiling or high on the ceiling of every level of the house close to each bedroom. Properly installed and maintained smoke detectors can reduce the tragic consequences of home fires, but even greater gains can be made by combining these early warning systems with a reduction in home fire hazards and in practicing a well planned fire escape route.