scholarly journals Study of protective efficiency of respirator with forced air supply

2020 ◽  
Vol 10 (6) ◽  
pp. 192-201
Author(s):  
Nataliiа Borodina ◽  
Serhii Cheberiachko ◽  
Yurii Cheberyachko ◽  
Оleg Deryugin ◽  
Dmytro Radchuk ◽  
...  
Keyword(s):  
Protective Action ◽  
Experimental Studies ◽  
Air Purification ◽  
Positive Pressure ◽  
Respiratory Protection ◽  
Protection Factor ◽  
Modes Of Operation ◽  
Air Supply ◽  
Forced Air ◽  
Protective Effectiveness

The aim of the work was to conduct experimental studies aimed at determining the protection factor of the filter respirator with forced air supply by volunteers in different modes of operation and to establish the dependence of the amount of air supplied by the fan from the air purification device to the filter’s resistance. Simulation studies to determine the protective effectiveness of the filter respirator on the testers were performed according to the procedure for determining the penetration coefficient of test aerosol – sodium chloride, as the ratio of the submask concentration of test aerosol to the ambient concentration formed in a special chamber that meets the requirements of DSTU EN 13274. Determination of the amount of air supplied by the air purification unit to the submask space and assessment of the value of positive pressure inside the mask was performed according to the procedure described in DSTU EN 12941: 2004. As a result of simulated laboratory tests to determine the protective effectiveness of filter respirators with forced air supply to the testers, it was found that the average result of the protection factor of the test samples ranged from 99.93 to 99.97, which meets the requirements of DSTU EN 12941: 2004. In addition, it was found that the amount of air treated by the fan of the air purification device for clean filters is 165 and 215 dm3/min for operating modes “Normal” and “Turbo”, while for the polluted filters it is reduced to 131 and 185 dm3/min, respectively. During the study, the compliance of the value of excess pressure in the submask space with the requirements of DSTU EN 12941: 2004, which should not exceed 2.5 mbar, was confirmed. It is also determined that the stability of the technical parameters of the air purification device is maintained in the specified range when charging the “Dinogy Li-Pol 11000mAh 14.8V 4S 25C” brand battery not less than 12 V to ensure the current value of not less than 1.6 A. The practical value of the results lies in determining the duration of protective action of the filter respirator, the choice of filter resistance to establish the scope and modes of operation in the developed personal respiratory protection equipment.

scholarly journals Research on Regularities of Cyclic Air Motion through a Respirator Filter

2021 ◽  
Vol 11 (7) ◽  
pp. 3157
Author(s):  
Oleg Bazaluk ◽  
Alim Ennan ◽  
Serhii Cheberiachko ◽  
Oleh Deryugin ◽  
Yurii Cheberiachko ◽  
...  
Keyword(s):  
Pressure Drop ◽  
Protective Action ◽  
Air Flow ◽  
Experimental Studies ◽  
Physical Activities ◽  
Brinkman Equation ◽  
Physical Work ◽  
Respiratory Protection ◽  
Human Respiration ◽  
Air Motion

In this paper, a solution to the problem of the change in the pressure drop in a respirator filter during cyclic air motion is suggested since the current theory of filtering is based on steady-flow processes. The theoretical dependence of the pressure drop in the respirator filter on air flow rate is determined, which is represented by the harmonic law, which characterizes the human respiration process during physical work. For the calculation, a filter model was used, which is represented by a system of parallel isolated cylinders with a length equal to the total length of the filter fibres surrounded by porous shells formed by a viscous air flow field, with a size determined by the equal velocities of the radial component of air flow and undisturbed flows. The flow-around process in the proposed model of air flow through the respirator filter is described by the Brinkman equation, which served to establish the total air flow resistance in the proposed system under conditions of velocity proportionality. It consists of two parts: the first characterizes the frictional resistance of the air flow against the surface of the cylinder, which imitates the filter fibre; the second—the inertial part—characterizes the frequency of pulsations of respiratory movements during physical performance. The divergence of the analytical results and experimental studies is no more than 20%, which allows the use of the established dependence to estimate the change in pressure drop in a respirator filter made of filter material “Elephlen” when the user carries out different physical activities. This allows the period of effective protective action of respirators with different cycles of respiration during physical activities to be specified, which is a very serious problem that is not currently regulated in health and safety regulations, and it also allows the prediction of the protective action of filters and respiratory protection in general.

Laccase-catalyzed enzymatic dyeing of cotton fabrics

2021 ◽  
pp. 004051752110069
Author(s):  
Rıza Atav ◽  
Bürhan Buğdaycı ◽  
Ömer Bozkurt ◽  
Aylin Yıldız ◽  
Elçin Güneş ◽  
...  
Keyword(s):  
Experimental Studies ◽  
Uv Protection ◽  
Infrared Analysis ◽  
Synthetic Dyes ◽  
Protection Factor ◽  
Knitted Fabrics ◽  
Reactive Dyeing ◽  
Dyeing Process ◽  
Laccase Enzyme ◽  
Color Reproducibility

As some synthetic dyes are regarded to be toxic, mutagenic and carcinogenic, the search for eco-friendly alternatives for the synthesis of dyes and coloration has gained importance. For this reason, this study focused on finding new eco-friendly alternatives for coloring cotton. 100% cotton knitted fabrics were subjected to enzymatic coloration using a commercial laccase enzyme and various precursors. After determining the colors, the effect of pH on the enzymatic dyeing process was investigated. Then the optimization of reaction conditions was also realized statistically for the precursors giving the best results in terms of color. With the aim of obtaining further improvements in color-yield values obtained in enzymatic dyeings, the effect of the pretreatment process and the use of ultrasound were also investigated. Furthermore, the reaction pathways in enzymatic coloration were explained and results were confirmed by means of Fourier Transformed Infrared analysis. As a result of experimental studies, red and lilac colors could be successfully obtained on cotton for the first time in the literature. In this way, the theoretical basis of enzymatic dye synthesis and dyeing of cotton was clarified comprehensively. Furthermore, technical (color reproducibility; washing, rubbing, light and perspiration-fastness values; and UV protection factor), economical (chemical, energy and water consumption required for dyeing (including aftertreatments) of 1 kg fabric) and ecological aspects of enzymatic dyeings were compared with reactive dyeing. According to the experimental results it was found that biological treatment alone was enough for wastewater of enzymatic coloring, while chemical treatment will also be needed in reactive dyeing wastewater. Furthermore, color reproducibility, evenness and UV protection properties of dyed samples were comparable with that of reactive dyeings. However, in terms of the fastness levels achieved, the enzymatic coloring was far behind the reactive dyeing.

Thermal and mechanical improvement of the air supply system of a turbocharged piston engine

2021 ◽  
Vol 14 (2) ◽  
pp. 108-114
Author(s):  
Y. M. Brodov ◽  
L. V. Plotnikov ◽  
K. O. Desyatov
Keyword(s):  
Heat Transfer ◽  
Experimental Studies ◽  
Local Heat Transfer ◽  
Supply System ◽  
Scale Model ◽  
Piston Engine ◽  
Intake System ◽  
Gas Dynamic ◽  
Air Supply ◽  
Air Flows

A method of thermomechanical improvement of pulsating air flows in the intake system of a turbocharged piston engine is described. The main objective of this study is to develop a method for suppressing the rate of heat transfer to improve the reliability of a piston turbocharged engine. A brief review of the literature on improving the reliability of piston engines is given. Scientific and technical results were obtained on the basis of experimental studies on a full-scale model of a piston engine. The hot-wire anemometer method was used to obtain gas-dynamic and heatexchange characteristics of gas flows. Laboratory stands and instrumentation facilities are described in the article. The data on gas dynamics and heat exchange of stationary and pulsating air flows in gas-dynamic systems of various configurations as applied to the air supply system of a turbocharged piston engine are presented. A method of thermomechanical improvement of flows in the intake system of an engine based on a honeycomb is proposed in order to stabilize the pulsating flow and suppress the intensity of heat transfer. Data were obtained on the air flow rate and the local heat transfer coefficient both in the exhaust duct of the turbocharger compressor (i.e., without a piston engine) and in the intake system of a supercharged engine. A comparative analysis of the data has been carried out. It was found that the installation of a leveling grid in the exhaust channel of a turbocharger leads to an intensification of heat transfer by an average of 9%. It was found that the presence of a leveling grid in the intake system of a piston engine causes the suppression of heat transfer within 15% in comparison with the baseline values. It is shown that the use of a modernized intake system in a diesel engine increases its probability of failure-free operation by 0.8%. The data obtained can be extended to other types and designs of air supply systems for heat engines.

scholarly journals Simulation of a Breathing Apparatus on Chemically Bound Oxygen with a Circular Pendulum Circuit of the Air Duct Part

2021 ◽  
pp. 46-52
Author(s):  
S.G. Ekhilevskiy ◽  
◽  
O.V. Golubeva ◽  
E.P. Potapenko ◽  
◽  
...  
Keyword(s):  
Maximum Permissible Concentration ◽  
Protective Action ◽  
Dead Layer ◽  
Respiratory Protection ◽  
Sorbent Layer ◽  
Breathing Resistance ◽  
Breathing Apparatus ◽  
Short Period ◽  
The Dead ◽  
Made In

At present, the main prospects for improving the insulating means of respiratory protection are associated with the chemical method of oxygen reservation. The arguments in favor of this choice are the high packing density of oxygen and its self-regulating supply, depending on the physical activity of a person. The main schemes of the air duct part of breathing apparatus on chemically bound oxygen are circular and pendulum. The attempt is made in the article to combine the advantages of the circular (small harmful space) and pendulum (small volume of the dead layer) schemes of breathing apparatus on chemically bound oxygen. For these purposes, the formalism method was developed, which allows mathematically and with the help of a computer to simulate the dynamic sorption activity of the regenerative cartridge of a breathing apparatus with a hybrid (circular-pendulum) scheme of the air duct part. The increase in the protective action of the apparatus is determined due to the use of the resource of the dead sorbent layer in the result of the air flow reverse in the pendulum part of the regenerative cartridge. Feasibility of using a hybrid scheme in the self-rescuers with a short period of protective action is shown. The optimal length of the pendulum part is determined, at which the breathing resistance decreases, and the harmful space occupied by the air returning for inhalation without contact with the unreacted layers of the oxygen-containing product is not increased. Its weak dependence on the total length of the regenerative cartridge and the maximum permissible concentration of carbon dioxide in the air returning to inhalation is shown, which makes the circular pendulum scheme realizable in practice.

scholarly journals Research of the hydraulic resistance of the granular filter of the sweeping mashnine

2019 ◽  
Vol 135 ◽  
pp. 01049
Author(s):  
Rashid Sharapov
Keyword(s):  
Hydraulic Resistance ◽  
Experimental Studies ◽  
Air Purification ◽  
Technological Parameters ◽  
Variable Parameters ◽  
Granular Filter ◽  
Modern Cities ◽  
Mathematical Expressions ◽  
Cleaning Equipment ◽  
Analytical Expressions

The article focuses on the need to improve the ecology in modern cities based on the development of new cleaning equipment. It is proposed to use a granular filter as a dust cleaning unit in sweeping machines. The advantages of granular filters over other types of filtering apparatus are given. The basic schemes of working equipment of sweepers are considered. To describe the processes during air purification in the proposed granular filter, mathematical expressions are proposed to determine the hydraulic resistance of the proposed filter. When developing analytical expressions, the structural and technological features of the proposed filter were taken into account. The results of calculating the hydraulic resistance of the proposed granular filter depending on its main structural and technological parameters are obtained. To confirm the obtained analytical expressions, experimental studies were carried out. The clinker of the Belgorod cement plant of a fraction of -10 + 5 mm was selected as the filtering material. During the experiment, cement was used as dust with a specific surface of various dispersion, determined by the parameter δ50. In addition, filtering speed and filtering time are accepted as variable parameters.

scholarly journals Cardioprotective Properties Of Xenon

2020 ◽  
Vol 9 (2) ◽  
pp. 264-272
Author(s):  
A. I. Shpichko ◽  
O. A. Grebenchikov ◽  
I. V. Molchanov ◽  
A. K. Shabanov ◽  
N. P. Shpichko ◽  
...  
Keyword(s):  
Clinical Trials ◽  
Clinical Practice ◽  
Randomized Clinical Trials ◽  
Protective Action ◽  
Experimental Studies ◽  
Molecular Targets ◽  
Cardiac Complications ◽  
Ischemia And Reperfusion

Abstract The review presents the main aspects of the cardioprotective properties of the xenon inhalation anesthetic. Based on the analysis of publications, the article discusses modern views on the mechanisms of the protective action of xenon, realized using pre- and post-conditioning mechanisms, shows major molecular targets and their effects. The article presents the results of experimental studies in vivo and in vitro, which showed the protective effect of xenon on the myocardium and the results of recent randomized clinical trials. The analysis of studies demonstrates the ability of xenon to increase myocardial resistance to ischemia and reperfusion and opens up good prospects for its use in clinical practice in patients with a high risk of cardiac complications.

scholarly journals Lower-Body Positive Pressure Treadmill Training for Pediatric Gait Disorders: A Scoping Review

2021 ◽  
Vol 12 (1) ◽  
pp. 323
Author(s):  
Yosra Cherni ◽  
Léandre Gagné-Pelletier ◽  
Laurent Bouyer ◽  
Catherine Mercier
Keyword(s):  
Children And Adolescents ◽  
Scoping Review ◽  
Lower Limb ◽  
Experimental Studies ◽  
Relevant Information ◽  
Treadmill Training ◽  
Positive Pressure ◽  
Lower Body Positive Pressure ◽  
Gait Parameters ◽  
Quasi Experimental

The purpose of this scoping review was to examine the literature on the use of anti-gravity treadmills and its effects on lower-limb motor functions in children and adolescents with locomotor impairments. Method: Four databases (MEDLINE, CINAHL, Embase, Web of Science) were searched for articles from inception to August 2021. Inclusion criteria were: (1) experimental or quasi-experimental studies using anti-gravity training as the primary intervention; (2) studies conducted in pediatric participants; (3) articles reporting outcomes related to lower-limb functions; and (4) studies published in French or English. Results: Fifteen articles were included in the review. Studies included children and adolescents aged 4–18 years with locomotor impairments. Intervention duration ranged from 2 to 12 weeks, with 2–5 sessions per week. Included studies reported that anti-gravity training induces improvements in muscle strength, balance, spatiotemporal gait parameters, and walking endurance in children with locomotor impairments. Conclusion: This review provides relevant information about interventions, outcomes and limits associated with anti-gravity training in pediatrics. Overall, anti-gravity treadmill training could be viewed as a valuable training modality, specifically for children with cerebral palsy. However, a more precise and comprehensive description of anti-gravity training protocols would be useful.

Experimental Studies on Fire Spread Over Glass Fac¸ade

2010 ◽  
Author(s):  
C. L. Chow ◽  
W. K. Chow
Keyword(s):  
Southern China ◽  
Experimental Studies ◽  
Fire Spread ◽  
Glass Pane ◽  
Air Supply ◽  
Smoke Spread ◽  
Upper Level ◽  
Set Up ◽  
Fire Flame ◽  
Real Scale

There are concerns on the behaviour of glass fac¸ade under a big fire. Real-scale experiments on a single-skin fac¸ade were carried out at a large laboratory of a sizable aluminum manufacturing plant in Southern China. Burning behaviour of a three-storey high single-skin glass fac¸ade with double glazing due to an adjacent big room fire was studied. Part of the fac¸ade of width 12 m and height 13 m was installed in a testing tower. A glass pane of the fac¸ade was taken out with a model fire chamber placed next to the opening. Flashover in the chamber was set up by burning a 2 MW gasoline fire. Flame and smoke spread from the chamber would move up along the glass fac¸ade. Air temperature outside the glazing above the fire chamber was measured. It is observed that flame spread out of the opening will be attached to the upper levels. The glass fac¸ade at that level will be heated up and broken. Flame can spread to the room at the upper level. Another flashover fire will then occur with adequate air supply. This scenario on having a post-flashover fire in an adjacent upper room should be included in hazard assessment in buildings with glass fac¸ade.

Towards Energy Efficient Air-Conditioned Space: Fluid Flow and Thermal Behavior

2013 ◽  
Author(s):  
Essam E. Khalil ◽  
Ahmed A. Medhat
Keyword(s):  
Numerical Modeling ◽  
Full Scale ◽  
Measuring Instruments ◽  
Air Velocity ◽  
Air Supply ◽  
Seminar Room ◽  
Computer Based ◽  
Prandtl Numbers ◽  
Forced Air ◽  
Air Streams

This paper focuses on both experimental investigation and numerical modeling of full-scale modelled air-conditioned multipurpose hall fully operable. Two methodologies were used, firstly full scale experimental setup was incorporated to map the hall making use of a well-developed fully automated wireless mobile test rig remotely controlled by pre-programmed computer and using high precision state-of-the-art measuring instruments. While the Second methodology was a numerical modeling using a well developed [CFD] 3DHVAC and FLUENT computer simulation programs. Physical and Numerical investigations enable the analyses of the influence of Reynolds, Archimedes and Prandtl numbers for the air as well as the effects of shape, location, inlet air velocity of supply outlet on the flowing air parameters. These parameters include throw, drop, air induction, room local velocities, humidity ratio and temperatures distributions. The forced air supply of cooled air streams out of high wall mounted, downward inclined jets is investigated with mechanically extracted air from the top of the split air-conditioning units. On the other hand an experimental traversing mechanism, computer-based and operated by PLC was developed and used to map the velocity and temperature contours. The room was typically used as the chairman office, meeting room and seminar room. One of the main conclusions is that good agreement between both of full-scale physical modeling and numerical modeling were reported. While the reported comparisons concluded that qualitative agreements were shown, some discrepancies were also observed in the thermal parameters for comfort conditions required by different occupants.

Design of Control Scheme for Variable Air Volume Air-Conditioning System

2014 ◽  
Vol 686 ◽  
pp. 113-120
Author(s):  
Fan Zhang
Keyword(s):  
Temperature Control ◽  
Control Unit ◽  
Pressure Control ◽  
Volume Control ◽  
Positive Pressure ◽  
Air Conditioning System ◽  
Variable Air Volume ◽  
Air Volume ◽  
Air Supply ◽  
Control Scheme

The air quantity of variable air volume system for the rooms and the total air quantity of the system changes with the change of room load. Combined with the system composition in the laboratory, the paper determines the control scheme of the variable air volume system, that is, indoor temperature-control, indoor positive pressure control, air distribution static pressure control, air-supply temperature control and new air volume control. The dotted lines with arrows mean the output signals from the control unit to actuator, and the solid lines with arrows represent the input signals from the actuator to the control unit.

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