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.

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.

Pressure Drop of Unidirectional Air Flow Through Rock Beds

1981 ◽  
Vol 24 (4) ◽  
pp. 1010-1013 ◽  
Author(s):  
Pitam Chandra ◽  
Louis D. Albright ◽  
Gerald E. Wilson
Keyword(s):  
Pressure Drop ◽  
Air Flow ◽  
Flow Through

Respiratory Effectiveness of Cloth Masks

2021 ◽  
Vol 2 (4) ◽  
Author(s):  
Behnam Pourdeyhimi ◽  
Simon Schick ◽  
Robert Groten ◽  
Hooman Vahedi Tafreshi
Keyword(s):  
Pressure Drop ◽  
Test Methods ◽  
Respiratory Protection ◽  
Regulatory Requirements

The shortage of medical masks and respirators led to an explosion of cloth mask offerings.  In the absence of any regulatory requirements, and appropriate guidance, the medical masks vary greatly in their performance and have become more of a fashion item.    We review the filtration mechanisms and test methods and show data on common offerings.  Almost exclusively, the data suggest that cloth masks do not offer much of a protection, and many are poorly designed with only the pressure drop and fogging in mind; these compromise the performance of the entire mask. While cloth masks do not offer significant respiratory protection, it is still critical that masks are worn during pandemics regardless in that they do reduce the number of aerosols expelled by the wearer.

The importance of diversified physical activities in early childhood for later fundamental movement skills and physical activity level: a seven-year longitudinal study

2021 ◽  
Author(s):  
Paulina S. Melby ◽  
Peter Elsborg ◽  
Glen Nielsen ◽  
Rodrigo A. Lima ◽  
Peter Bentsen ◽  
...  
Keyword(s):  
Physical Activity ◽  
Structural Equation Models ◽  
Experimental Studies ◽  
Physical Activities ◽  
School Intervention ◽  
Activity Level ◽  
Life Course Perspective ◽  
Movement Skills ◽  
Fundamental Movement Skills ◽  
Daily Physical Activities

Abstract Background: Research indicates that childhood fundamental movement skills (FMS) can predict physical activity (PA) later in life and it has been argued that frequently engaging in a wide diversity of physical activities will eventually improve children’s FMS. However, no longitudinal or experimental studies have confirmed this hypothesis. The aims of this study are to investigate the longitudinal associations between diversified physical activities at age six and later FMS and PA (age nine and 13). Furthermore, we explore to what extent the longitudinal association between diversified physical activity and PA is mediated by FMS.Methods: Longitudinal data from the Copenhagen School Intervention Studywere used for this analysis, where 704 participated (69% response rate). Diversified physical activity (self-reported), FMS (The Körperkoordinationstest für Kinder battery of postural stability and locomotor skills) and PA (accelerometer) were assessed in the children at age six, age nine and age 13. A total of 991 participated in at least one of the measure years. Two structural equation models were constructed, with diversified physical activity at age six and FMS and PA at age nine as predictors of PA and FMS at age 13. Results: The data from both models demonstrated good model fit. Diversified physical activity at six years of age was significantly associated with physical activity and FMS at age 13, when adjusting for sex, age, intervention, weight, height, and previous levels of PA and FMS. Diversified physical activity at age six was also positively associated with PA and FMS at age nine, which were, in turn, positively related to PA at age 13 but to a lesser degree than diversified PA at age six. The association between diversified physical activity at age six and PA at age 13 was not mediated by FMS at age nine. Conclusions: The results of this study indicate that diversified physical activity at age six is important for the development of FMS and PA in adolescence. Increasing the diversity of children’s daily physical activities, not only the amount and intensity, seems important for future PA behavior and thereby health promotion in a life course perspective.

Experimental Studies of Adiabatic Flow Boiling in Fractal-Like Branching Micro-Channels

2008 ◽  
Author(s):  
Brian J. Daniels ◽  
James A. Liburdy ◽  
Deborah V. Pence
Keyword(s):  
Pressure Drop ◽  
Void Fraction ◽  
Flow Boiling ◽  
Experimental Studies ◽  
Channel Length ◽  
Channel Height ◽  
Channel Network ◽  
Adiabatic Flow ◽  
Numerical Predictions ◽  
Micro Channels

Experimental results of adiabatic boiling of water flowing through a fractal-like branching microchannel network are presented and compared to numerical simulations for identical flow conditions. The fractal-like branching channel network had channel length and width ratios between adjacent branching levels of 0.7071, a total flow length of 18 mm, a channel height of 150 μm and a terminal channel width of 100 μm. The channels were DRIE etched into a silicon disk and pyrex was anodically bonded to the silicon to form the channel top and allowed visualization of the flow within the channels. The water flowed from the center of the disk where the inlet was laser cut through the silicon to the periphery of the disc. The flow rates ranged from 100 to 225 g/min and the inlet subcooling levels varied from 0.5 to 6 °C. Pressure drop across the channel as well as void fraction in each branching level were measured for each of the test conditions. The measured pressure drop ranged from 20 to 90 kPa, and the measured void fraction ranged from 0.3 to 0.9. The pressure drop results agree well with the numerical predictions. The measured void fraction results followed the same trends as the numerical results.

scholarly journals Research Active Posterior Rhinomanometry Tomography Method for Nasal Breathing Determining Violations

Sensors ◽  
2021 ◽  
Vol 21 (24) ◽  
pp. 8508
Author(s):  
Oleg G. Avrunin ◽  
Yana V. Nosova ◽  
Ibrahim Younouss Abdelhamid ◽  
Sergii V. Pavlov ◽  
Natalia O. Shushliapina ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Pressure Drop ◽  
Flow Rate ◽  
Dynamic Change ◽  
Air Flow ◽  
Current Mode ◽  
Forced Response ◽  
Point Of View ◽  
Air Flow Rate ◽  
Nasal Breathing

This study analyzes the existing methods for studying nasal breathing. The aspects of verifying the results of rhinomanometric diagnostics according to the data of spiral computed tomography are considered, and the methodological features of dynamic posterior active rhinomanometry and the main indicators of respiration are also analyzed. The possibilities of testing respiratory olfactory disorders are considered, the analysis of errors in rhinomanometric measurements is carried out. In the conclusions, practical recommendations are given that have been developed for the design and operation of tools for functional diagnostics of nasal breathing disorders. It is advisable, according to the data of dynamic rhinomanometry, to assess the functioning of the nasal valve by the shape of the air flow rate signals during forced breathing and the structures of the soft palate by the residual nasopharyngeal pressure drop. It is imperative to take into account not only the maximum coefficient of aerodynamic nose drag, but also the values of the pressure drop and air flow rate in the area of transition to the turbulent quadratic flow regime. From the point of view of the physiology of the nasal response, it is necessary to look at the dynamic change to the current mode, given the hour of the forced response, so that it will ensure the maximum possible acidity in the legend. When planning functional rhinosurgical operations, it is necessary to apply the calculation method using computed tomography, which makes it possible to predict the functional result of surgery.

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