scholarly journals SUB-LAYER EXTINGUISHING OF ALCOHOLS BY BINARY MIXTURES OF FIRE-EXTINGUISHING AEROSOL AND CO2

Fire Safety ◽  
2020 ◽  
Vol 36 ◽  
pp. 5-9
Author(s):  
V. Balanyuk ◽  
M. Kozyar ◽  
A. Kravchenko
Keyword(s):  
Binary Mixtures ◽  
Volume Concentration ◽  
Potassium Nitrate ◽  
Concentration Limit ◽  
Measuring Instruments ◽  
Minimum Volume ◽  
Explosion Pressure ◽  
Fire Extinguishing ◽  
Lower Concentration Limit ◽  
Fire Extinguishers

Introduction. Now the number of enterprises and technological processes where alcohols and alcohol-containing liquids are used is constantly increasing. Due to the content of carbon, hydrogen and oxygen in the molecule, alcohols have increased flammable properties, namely: high combustion temperature, low lower concentration limit of flame propagation, high evapo-ration rate due to low boiling point and significant explosion pressure. Thus, in order to increase the fire safety of alcohol enterprises, is relevant the search for fire extinguishers that would provide both surface extinguishing and volumetric phlegma-tization of alcohol-air mixtures .The purpose and objectives of the study. The aim of the work is to determine the fire extinguishing factors and the efficiency of sublayer extinguishing by binary mixtures of fire extinguishing aerosol and CO2.Research objectives To establish fire-extinguishing factors of sublayer extinguishing of alcohols by binary mixtures of fire-extinguishing aerosol and CO2. To determine the fire-extinguishing efficiency of sublayer extinguishing of alcohols by binary mixtures of fire-extinguishing aero-sol and CO2.Methods. In the work according to the developed method with the use of metrologically certified equipment and certified measuring instruments, the fire-extinguishing minimum volume concentration of the components of the binary gas-aerosol mixture on the developed installation was determined.6 Пожежна безпека, №36, 2020Results. It was found that the maximum fire-extinguishing intensity of the aerosol formed from aerosol based compound based on sucrose (33%), potassium nitrate KNO3 (67%), is about 6 g / s in the experimental setup. The fire-extinguishing inten-sities of aerosol supply and its binary mixture with CO2 have been experimentally established. It was found that the addition of CO2 to the aerosol reduces the time of emergence of gas aerosol bubbles and quenching to 1.5 times. It was found that the size of the bubbles when adding CO2 is 10 -35% larger than when using CO2 itself.Conclusions. The results of the research showed that binary gas-aerosol mixtures have high fire-extinguishing efficiency with their sublayer supply for extinguishing alcohols and are several times more efficient, cheaper and have several times longer service life compared to traditional fire extinguishers.

scholarly journals COMPARISON OF POTENTIALALLY DANGEROUS FACTORS WITH THE USE OF RARE AND GASILY VEHICLE

2019 ◽  
Vol 19 (1) ◽  
pp. 295-308
Author(s):  
V. Slovinskyi ◽  
G. Yelagin ◽  
Y. Alexeieva ◽  
V. Nakonetcnyi
Keyword(s):  
Diesel Fuel ◽  
Ignition Temperature ◽  
Concentration Limit ◽  
Closed Volume ◽  
Vapor Density ◽  
Explosion Pressure ◽  
Lower Concentration Limit ◽  
Gas Cylinder ◽  
Butane Mixture ◽  
Propane Butane

A detailed analysis of the potentially dangerous factors in the use of diesel, gasoline, methane and propane-butane fuels was carried out in cars. A detailed analysis of potentially dangerous factors when using diesel, gasoline, methane and propane-butane fuels in automobiles has been carried out. 6 options of fuel usage are considered: a tank with g asoline and a system supplying it to the carburetor and further to the engine cylinders, a tank with diesel fuel and the system feeding it to the engine cylinders, gas cylinder installation when installing cylinders with methane on the roof of the car, gas cylinder installation when mounting cylinders with methane in the luggage compartment of the car, gas installation when installing cylinders with propane-butane mixture on the roof of the car, gas installation when installing cylinders with propane-butane mixture in the cargo compartment of the car. Meanwhile, the potential danger while the vehicle is in motion is analyzed, as well as while it is in the open parking lot and in the garage. As the initial data, the common operation period was taken - in summer with the temperature of 30°C and possible fuel leakage with the probability of formation of an explosive mixture. Nonane is taken as a model when considering gasoline, and Pentadecane is used for diesel fuel. It was noted that the gasoline self-ignition temperature ranges from 255°С to 435°0С, the lower concentration limit of petrol explosiveness can be considered as 0.76% vol., while under selected conditions indoors, gasoline vapor can reach the concentration of up to 0.8 vol. %. The relative vapor density of diesel fuel betting the same conditions is 8.52 kg/m3. With the explosion, the pressure in the closed volume will reach 5.2 atm. It was noted that the gasoline self-ignition temperature ranges from 210°С to 370°0С, the lower concentration limit of petrol explosiveness can be considered as in % vol., while under selected conditions indoors, gasoline vapor can reach the concentration of up to 0.13 vol. %. With the explosion, the pressure in the closed volume will reach 5.0 atm. The self-ignition temperature of methane is 537°C, the lower concentration limit of explosiveness of this gas is 5.28% (vol). The vapor density of methane at the temperature of 300°C (303K) is 0.64 kg/m3, which is significantly less than the density of air. The explosion pressure in the closed volume will reach 7.7 atm. The propane-butane mixture used in summer contains about 40% of propane and 60% of butane. Spontaneous ignition temperature of propane is 4700C, butane is 4050C. The calculated lower explosion limit of this mixture is 1.5% (vol), and the vapor density of mixture at the temperature of 300°C is 2.1 kg/m3, which is almost twice the density of air under the same conditions. The calculated explosion pressure in the closed volume will reach 8.3 atm. It was concluded that when using certified equipment which is professionally installed, methane, which cannot accumulate in the lower part of the room or any compartment, is much safer than propane-butane and, especially, than gasoline or diesel fuel, as vapor densities of both are more than air density.

The Study of Fire-extinguishing Process of Modelled Fire Seats

2021 ◽  
pp. 57-62
Author(s):  
V.N. Bordakov ◽  
Keyword(s):  
Flow Rate ◽  
Experimental Studies ◽  
Physical Modelling ◽  
Specific Flow Rate ◽  
Specific Flow ◽  
Acceptable Error ◽  
Fire Extinguishing ◽  
Fire Zone ◽  
Analysis Of Results ◽  
Fire Extinguishers

Test-fires to determine fire-extinguishers’ efficiency for extinguishing B class fires are conducted by operators equipped with working clothes, which does not comply with the requirements of physical modelling. This is why the ranks of extinguished modelled seats are significantly overestimated. The quantitative results of fire seats’ extinguishing can be comparatively evaluated in accordance with the value of specific flow rate of a fire-extinguishing agent. As it was detected, the specific flow rate of a fire-extinguishing agent does not actually depend on the rank of modelled fire seat when extinguished by an operator wearing thermal-protective clothes. At the same time, it is increasing along with the expansion of the fire zone scale in case the fire is extinguished without special protective clothes. Consequently, to increase the fire-extinguisher’s efficiency data reliability, the certifying tests should be conducted in conditions close to the real application conditions when the first person to firefight is not equipped with such special protective clothes. The experimental studies to determine the specific flow rate of a fire-extinguishing agent used modelled fire seats of various ranks. The analysis of results showed that the fire-extinguishers ensuring generation of drops of prevailing size more than 0,5 mm are required to extinguish the modelled sire seats. The degree of increasing flow rate for the fire-extinguishing agent to eliminate a fire and observation of a safe distance from the flame for an operator are conditioned by the scale of fire zone and affect the specific flow rate of agent required to ensure stable fire-extinguishing. Based on the results of extinguishing the fire seats «34В» or «55В», it is demonstrated that via using a correction factor it is possible, assuming an acceptable error, to evaluate the flow rate of fire-extinguishing agent to extinguish a modelled fire seat of any rank.

Chemical composition of the renewed fire extinguishing powder and its physical characteristics

2020 ◽  
pp. 70-76
Author(s):  
Azzaya T ◽  
Burmaa G ◽  
Alen S ◽  
Batsaikhan V
Keyword(s):  
Fuel Oil ◽  
Physical Parameters ◽  
Endothermic Effect ◽  
Water Release ◽  
Release Process ◽  
Fire Extinguishing ◽  
Inorganic Substances ◽  
Main Component ◽  
Water Repellence ◽  
Fire Extinguishers

Water, foam, dry powder, carbon dioxide and liquid chemicals are used as fire extinguishers depending on the fire types. The fire classification of ABC type includes fires caused by paper, wood, dye, fuel, oil, lubricants and flammable gases. In this work, the investigation of the procedure for re-determining the composition of prepared fire extinguishers was carried out depending on the ratio of organic and inorganic substances, and their fire extinguishing activity was tested. The Sample-1 contains about 50% of ammonium dihydrophosphate (NH4H2PO4) which is taking into account the main component and the sum of ammonium sulphate (NH4)2SO4 and other inorganic and organic components by 50%. As a result of fire extinction tests, its fire extinguishing activity was higher than that of other Samples included different ratios of substances. Based on the thermogravimetric analysis of the Sample -1, the polymerization and water release process of NH4H2PO4 was detected as endothermic effect. The weight loss was occurred by 74% and 26% remained as P2O5 when temperature reached to highest degree. Some physical parameters such as moisture content, water repellence, density and particle size were analyzed according to ISO standard method and all these important parameters showed that it can meet the requirements for fire extinguishing powder standards. Гал унтраагч шинэчилсэн бэлдмэлийн найрлага, түүний физик шинж чанарын судалгаа Хураангуй: Ус, хөөс, хуурай нунтаг, нүүрс хүчлийн хий ба химийн шингэн бодис зэргийг галын төрлөөс хамааруулан гал унтраагчаар ашигладаг. Галын ABC ангилалд цаас, мод, будаг, шатахуун, тос, тосолгооны материал, шатамхай хий зэргээс үүдэлтэй гал хамаарна. Энэхүү ажлаар импортын гал унтраагч бодисын найрлагыг шинэчлэн тогтоох судалгааг органик ба органик бус химийн бодисуудын харьцаанаас хамааруулан явуулж, тэдгээрийн гал унтраах идэвхийг ABC ангиллын галд туршив. Үндсэн бүрдэл болох аммонийн дигидрофосфат (NH4H2PO4)-ыг 50%, (NH4)2SO4 ба бусад бүрэлдэхүүн бодисуудын нийлбэрийг мөн 50%-иар тооцоолон авсан. Бэлдмэл 1-ийн гал унтраах идэвх нь бусад бэлдмэлүүдийн идэвхээс өндөр байв. Бэлдмэлийн термографийн судалгаагаар NH4H2PO4-ын их хэмжээний дулаан шингээн полимержих, ус ялгаруулах процесс DTA-ийн муруйд эндо эффект хэлбэрээр илэрсэн ба температурын дээд утгад жингийн алдагдал 74%-д хүрч, 26% нь P2O5 хэлбэрээр үлдсэн. Гал унтраагч нунтгийн физик шинж чанарын гол үзүүлэлтүүд болох чийг, хувийн жин, ус үл нэвтрүүлэх чадвар, ширхэглэлийн хэмжээг тодорхойлсон ба эдгээр үзүүлэлтүүд нь стандартын шаардлагуудыг хангасан байна. Түлхүүр үг: Гал унтраагч нунтаг, идэвх, аммонийн дигидрофосфат, DTA/TG, физик үзүүлэлт  

scholarly journals A Study on the Durability of Fire Hoses of Fire Hydrants

2021 ◽  
Vol 21 (6) ◽  
pp. 97-102
Author(s):  
Hakjoong Kim ◽  
Youngjoo Song
Keyword(s):  
Service Life ◽  
Case Analysis ◽  
Fire Fighting ◽  
Sample Analysis ◽  
Property Damage ◽  
Human Safety ◽  
Fire Extinguishing ◽  
Years Of Service ◽  
Fire Spreading ◽  
Fire Extinguishers

Although the number of fires has not changed considerably in recent times, property damage and casualties due to fires are increasing every year. Maintaining the performance of fire-fighting facilities installed in buildings has been emphasized for maximizing human safety and minimizing property damage caused by fires. As a result, since 2017, the maintenance of fire extinguishers throughout their service life, has been mandated. In case of a fire, initial fire extinguishing and fire spreading prevention are crucial. There have been no available measures for the maintenance and verification of indoor fire hydrants and outdoor fire hydrant hoses used for extinguishing fires and preventing combustion expansion. This study was therefore intended to present measures for ascertaining the service life of these fire extinguishers, by evaluating their firefighting abilities through sample analysis and case analysis of the fire hoses. Research shows that the degradation of performance of the fire hoses becomes evident between 9 and 10 years, so that 10 years of service life is considered appropriate for the fire hoses.

A Quantitative Comparison of Methods Measuring Fluoride in Solutions or in Enamel

1992 ◽  
Vol 71 (3_suppl) ◽  
pp. 945-948 ◽  
Author(s):  
J.J. Ten Bosch ◽  
M. Booij
Keyword(s):  
Personal Experience ◽  
Physical Nature ◽  
Standard Addition ◽  
Quantitative Comparison ◽  
Concentration Limit ◽  
Good Resolution ◽  
Good Sensitivity ◽  
Straightforward Manner ◽  
Lower Concentration Limit ◽  
High Concentrations

Fluoride in solution is most usually measured with the ion-specific electrode, although a few other methods are available. The electrode can be used in a straightforward manner, its lower concentration limit may be extended by special methods such as the standard addition of fluoride, or microdiffusion methods may be used to extract fluoride from the sample and concentrate it in base. Specifications of all methods are tabulated. A choice of method depends on the requirements in terms of specifications but also on the personal experience of the investigator and the required robustness. Microdiffusion of some kind is preferable for concentrations below 5 μmol/L or when electrode-interfering molecules such as proteins are present in rather high concentrations. Fluoride in enamel may be determined by removal of layers by etching, abrasion, or microdrilling, followed by dissolution of the layer removed. Specifications of depth and area resolution are tabulated. Alternatively, probing methods of a physical nature can be used. These methods require sophisticated instruments that are not widely available. Some of them are destructive, others are not. All but one require exposure to vacuum. However, most of them combine a very good sensitivity with a very good resolution in depth and/or measured area. Therefore, their use in research (requiring cooperation with instrument specialists/owners) may well be worth the effort.

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