Comparison of fire extinguishing performance of four halon substitutes and Halon 1301

2021 ◽  
pp. 073490412110301
Author(s):  
Yawei Wang ◽  
Gaowan Zou ◽  
Conglin Liu ◽  
Y Gao

The Halon 1301 fixed gas fire extinguishing system used in ship engine rooms has been banned from production all over the world, because halon destroys the ozone layer. Therefore, it is necessary to find an environmentally friendly, compatible and efficient alternative firefighting system. In this study, we performed fire extinguishing tests in an ISO9705 standard room for four alternative fire extinguishing agents, as well as Halon 1301. The fire extinguishing efficiency of each agent was determined based on its cooling effect, dilution effect of oxygen concentration, the extinguishing time of the oil pool fire and the re-ignition probability of the wood stack. The test results provide data support for the selection of alternatives of Halon 1301 from the aspect of fire extinguishing efficiency. Among these results, Novec 1230 had the best ability to put out the oil pool fire, and HFC-227ea suppressed the wood stack fire the best. The difference between the cooling ability of each fire extinguishing agent was small, and the inert gas (IG-541) displayed the best ability to dilute oxygen. Hot aerosol required the longest time to extinguish fire. Consequently, under the existing design standards, HFC-227ea had the better firefighting efficiency, more suitable to replace Halon 1301.

2013 ◽  
Vol 790 ◽  
pp. 686-689
Author(s):  
Chen Jian ◽  
Xu Yan Ying ◽  
Wang Yan Sheng

The objective of this work is to investigate the diesel analog pool fire with water mist .For this purpose, a series of water mist fire suppression experiment are carried out by changing the nozzle operating pressure, the source of fire power, opening and closing the exhaust fan to analyze the inhibitory effect of water mist to oil pool fire in the enclosed compartment of 5.0m × 5.0m × 3.0m. The results shows that extinguishing efficiency first increases and then decreases when the nozzle operating pressure increases from 8MPa to 12MPa, reaching the highest efficiency at 10MPa; increasing the power of the source of fire, the burning speed increases and the water mist fire extinguishing efficiency decreases; fresh oxygen coming in when smoke exhaust fan is turned on and water mist fire suppression efficiency decreases. Using FDS to simulate the water mist extinguishing oil pool fire, the predict temperature field and extinguishing time are basically consistent with the experimental results. In the actual applications of water mist fire suppression systems engineering, we can use the FDS field simulation methods to predict the characteristic parameters variation of the fire fighting fire temperature and component concentration, which is significant to the fire extinguishing system optimized design.


2018 ◽  
Vol 247 ◽  
pp. 00003
Author(s):  
Bożena Kukfisz

The paper describes the impact of adding fire extinguishing powders acting based on oxygen or flame on values of minimum ignition temperatures of the layer and cloud of pellet dust, and as a consequence the impact or lack of impact on values of maximum admissible temperature on external surfaces of electrical appliances working in their atmospheres. Tests were conducted of the minimum ignition temperature of layer and cloud of the agro armakow pellet dust and the agro jesień pellet dust, with and without additives of fire extinguishing powders BC Jet, BC LB2, ABC 90 and Ogniotex 103 at concentrations ranging from 5 to 70% by weight of powder contents in the mixture. Based on obtained test results it has been ascertained that type ABC powders appear to be much more effective than those type BC, because they have a much bigger impact on increasing the minimum ignition temperature of the layer and the cloud of analysed dust types. Adding only 15% of ABC 90 extinguishing powder to the agro jesień pellet has caused an increase in the minimum ignition temperature of dust layer by 80°C. The BC LB2 powder with agro armakow pellet dust has not been found to cause any changes, even at its concentration as high as 70%. The most optimum additive of powder to the biomass dust was 10% by weight of ABC powder in the mixture. At this concentration the highest increase was recorded in the maximum admissible temperature on the outer surface of electrical appliances from 235°C to 273°C.


2018 ◽  
Vol 31 (5) ◽  
pp. 436-449 ◽  
Author(s):  
Depeng Kong ◽  
Zhen Zhang ◽  
Ping Ping ◽  
Xu He ◽  
Hanbing Yang

2005 ◽  
Vol 32 (6) ◽  
pp. 1075-1081 ◽  
Author(s):  
Ashraf M Ghaly ◽  
James D Cahill IV

Waste rubber tires that cannot be processed for useful applications are numbered in the millions around the world. The build up of old rubber tires in landfills is commonly considered a major threat to the environment, and it is unquestionably a burden on landfill space. This research project was an investigation into the possibility of using fine rubber particles in concrete mixtures. The experimental testing program was designed to study the effect of the addition of crumb rubber, as replacement of a portion of fine aggregates (sand), on the strength of concrete. Rubber was added to concrete in quantities of 5%, 10%, and 15% by volume of the mixture. Three different water/cement ratios were used: 0.47, 0.54, and 0.61. A total of 180 concrete cubes were made. The cubes were tested in compression at 1, 7, 14, 21, and 28 d with the load continuously and automatically measured until failure. The load values were used to calculate compressive stress as related to different rubber contents and water/cement ratios. Compression test results were used to develop several plots relating rubber content and water/cement ratio to compressive stress of concrete. Test results gathered in this research project indicated that the addition of crumb rubber to concrete results in a reduced strength as compared with that of conventional concrete. Based on the experimental results, correlations have been developed to estimate the reduction in concrete strength as a function of the rubber content in the mix.Key words: compressive strength, concrete, crumb rubber, rubberized concrete.


1998 ◽  
Vol 1 (4) ◽  
pp. 273-286 ◽  
Author(s):  
J. Michael Rotter

Thin axially compressed cylinders are used in a wide range of civil engineering shell structures: towers, chimneys, tanks and silos. Design standards throughout in the world differ considerably in their strength predictions, and all are based on empirical lower bounds to laboratory test results. The chief reason for the scatter in strength assessments is the sensitivity to geometric imperfections, which naturally vary from one laboratory to another and according to the method of fabrication. This paper sets out some of the development behind the new proposed rules for the European standard on Strength and Stability of Shells. These rules cover cylinder buckling under axial compression alone, and the strength of internally pressurised cylinders. The design strengths are related to recent calculated buckling strengths, and an attempt is made to indicate the appropriate relationship between design assumed imperfections and tolerances during construction.


Author(s):  
Douglas Spangler ◽  
Hans Blomberg ◽  
David Smekal

Abstract Background The novel coronavirus disease 2019 (Covid-19) pandemic has affected prehospital care systems across the world, but the prehospital presentation of affected patients and the extent to which prehospital care providers are able to identify them is not well characterized. In this study, we describe the presentation of Covid-19 patients in a Swedish prehospital care system, and asses the predictive value of Covid-19 suspicion as documented by dispatch and ambulance nurses. Methods Data for all patients with dispatch, ambulance, and hospital records between January 1–August 31, 2020 were extracted. A descriptive statistical analysis of patients with and without hospital-confirmed Covid-19 was performed. In a subset of records beginning from April 14, we assessed the sensitivity and specificity of documented Covid-19 suspicion in dispatch and ambulance patient care records. Results A total of 11,894 prehospital records were included, of which 481 had a primary hospital diagnosis code related to-, or positive test results for Covid-19. Covid-19-positive patients had considerably worse outcomes than patients with negative test results, with 30-day mortality rates of 24% vs 11%, but lower levels of prehospital acuity (e.g. emergent transport rates of 14% vs 22%). About half (46%) of Covid-19-positive patients presented to dispatchers with primary complaints typically associated with Covid-19. Six thousand seven hundred seventy-six records were included in the assessment of predictive value. Sensitivity was 76% (95% CI 71–80) and 82% (78–86) for dispatch and ambulance suspicion respectively, while specificities were 86% (85–87) and 78% (77–79). Conclusions While prehospital suspicion was strongly indicative of hospital-confirmed Covid-19, based on the sensitivity identified in this study, prehospital suspicion should not be relied upon as a single factor to rule out the need for isolation precautions. The data provided may be used to develop improved guidelines for identifying Covid-19 patients in the prehospital setting.


2019 ◽  
Vol 160 (38) ◽  
pp. 1503-1509
Author(s):  
Réka Szabó ◽  
Gergely Farkas ◽  
Mária Keszeg ◽  
Gabriella Eördegh ◽  
Norbert Buzás ◽  
...  

Abstract: Introduction: The compromise effect is a well-known phenomenon in the world of marketing, but it is rarely examined in medical settings. In dental setting, the patient often has to make treatment-related decisions with price as the only available and comprehensible information to help informed choice. Aim: We sought to determine if the compromise effect plays a role in dental treatment choices, and if yes, how the effect is modified by factors such as perceived quality, professional jargon in the explanations, or the importance of keeping one’s own teeth intact. Method: 676 volunteers participated in this questionnaire-based study. The questionnaires were filled in anonymously. Altogether 8 versions of the same questionnaire were generated, in which the following information was given in varying combinations: the names of five different dental treatments from cheap to expensive, their possible prices, and additional information about the treatment. Statistical analysis: The significance of the relationship between the relative frequency of responses and the available additional information was determined by chi-square test and Fisher’s exact test. Results: The respondents did not approach dental treatment-related decisions on a heuristic basis by default, most probably because of their preconceptions and previous experiences in connection with dental treatments. Esthetics turned out to be of utmost importance and expectable lifespan was also information that significantly influenced the choices. Conclusion: Extra information can and does influence informed dental treatment choice on the patient side, provided it is offered in a clear, proper, and intelligible form, which points out the importance of professional communication. Orv Hetil. 2019; 160(38): 1503–1509.


2018 ◽  
pp. 11-12
Author(s):  
B. S. Salomov ◽  
M. H. Aramov

A large number of forms and varieties of garlic created in the selection process allowed this culture to spread almost all over the world: in temperate regions, in subtropics and even in tropical regions. Currently, the world's acreage of garlic is 1.438 million hectares, the average yield is 16.9 tons per hectare, the gross yield is 24.255 million tons. The largest producers of garlic are China, India, South Korea and Egypt. The highest yield was recorded in Uzbekistan, Egypt, China, Tadjikistan. In Uzbekistan, it is grown everywhere, mainly on household plots and small areas in farms. In the republic, varieties of garlic are South-violet (1972) and May VIR (1978). Since 2004, the Surkhandarya Scientific Experimental Station of the VegetableMelon Crops and Potato Research Institute has been conducting selection work to create new varieties of garlic. As a result of the research, the Chidamli variety was introduced and, since 2016, introduced into the State Register. All zoned varieties belong to the group of autumn-sprouting varieties. In 2011- 2015, about 100 promising clones of garlic were evaluated in the south of Uzbekistan. The effectiveness of selection for the size of bulbs and teeth is revealed. Clones with a mass of bulbs and teeth are isolated. Clones with a bulb weight of more than 80 g and a tooth mass of more than 6 g are distinguished. They are a valuable source for the creation of high-yielding varieties of garlic in Uzbekistan.


2017 ◽  
Vol 3 (1) ◽  
pp. 1-5
Author(s):  
M Shakir Khan

The problem of radon in dwellings gained importance in 1984 after an incidence in Pennsylvania, USA; thereafter several measuring techniques have been developed and national survey programs were started throughout the world for monitoring radon levels by government authorities. The lots of work have done by researchers in this field throughout the world. Several developed countries have given guidelines for initiating action to reduce radon levels if found beyond permissible level. The main aim of this article to provide public awareness about the health hazards posed by radon, which is naturally occurring invisible inert gas in the dwellings that is not be detected by human senses.


2016 ◽  
Vol 3 (1) ◽  
pp. 001
Author(s):  
Awis Hardjito

Competition occurs among Islamic banks increasingly tight. In order to survive and remain competitive, an Islamic bank should have an identity and uniqueness which differentiates with other Islamic banks. BRI Sharia in order to enter the world of competition and survive should implement strategies remain competitive advantages to maintain the loyalty of its customers. These strategies are divided into cost leadership, differentiation and focus. The expectation by applying one of these strategies, BRI Sharia can retain the loyalty of the customers and gain new customers. This research aimed to determine which strategies are applied by BRI Sharia. The strategies of the competitive advantage created by M. Porter's such as cost leadership, differentiation, and focus affect significantly on customer loyalty. Data processing was performed using SEM analysis (Structural Equation Model). The results showed that customer loyalty variation can be explained by variabel s of cost leadership, differentiation and focus strategies. From the test results we can conclude that only cost leadership strategy variable that significantly affect customer loyalty of BRI Sharia.


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