# On Development of a New Filtering Half-Mask

S.I. Cheberyachko, Radchuk D.I., Cheberyachko Y.I., Ziborova M.O.

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S.I. Cheberyachko, Radchuk D.I., Cheberyachko Y.I., Ziborova M.O. On Development of a New Filtering Half-Mask. Mechanics, Materials Science & Engineering Journal, 2016, 10.13140/RG.2.1.3389.4802. hal-01306153

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Submitted on 22 Apr 2016

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# On Development of a New Filtering Half-Mask

S.I. Cheberyachko¹, D.I. Radchuk², Y.I. Cheberyachko², M.O. Ziborova³

1 – Professor, National Mining University, Ukraine

2 – Associated professor, Dnepropetrovsk National University, Ukraine

3 – M.Sc., National Mining University, Ukraine

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DOI 10.13140/RG.2.1.3389.4802

**Keywords:** penetration ratio, heat exposure, fiber, polypropylene filter, Leaf-type respirators.

**ABSTRACT.** The paper describes adapting problems for respirators, produced in Ukraine to European standards. It was found that the Leaf type respirator of FPP material doesn't meet the parameters of DSTU EN 149: 2003 at a rate of dust penetration through the respirator filter after thermal and mechanical influences and flameproof. Study has shown, that increasing duration of heat exposur the structure of the filter material undergoes irreversible changes. This leads to a decrease in the protective efficiency. Using polypropylene filter materials allow replacing FPP materials, which indicators meets European standards, and do not contradict the traditional view of potential consumers.

**Introduction.** Dust bronchitis and pneumoconiosis today dominate among all occupational diseases. Their level is formed by the coal and mining industry and is 60 – 70% [1]. This is due to lack of efficacy and collective means of protection and violation of the process, that leads to a deterioration of working conditions, and non-compliance with safety regulations, and the lack of effective control of the dust load. In addition, the chemical composition of the mine dust is very diverse and may contain lead and mercury, fluoride and arsenic materials, compounding effect on the body of silica present in the rock dust [2]. Influence of the dust dispersion generally predominate with fraction particle size less, than 5 microns [3].

A significant role in the prevention of occupational diseases caused by dust factor is personal protective respirators (RPE). The most widely used in the mining industry respirator type "Leaf". Its technical characteristics allow providing sufficiently high protection (enough lifetime during dust concentration 200 mg/m³) as opposed to a combination of other samples has a minimal effect on the functional state of the person. Note, that for the manufacture of the respirator previously used filter material *FPP*, which is characterized by its fiber electrostatic charges, which significantly increase the capture of fine dust particles [4].

The reason for this discrepancy is that the material *FPP* can resist mechanical deformation and do not collapse, as it consists of dry fibers bonded at points of contact only by adhesion forces, and pressed to each other by electrical forces [6]. Irreversible damaging influence of mechanical action can cause significant penetration of the test aerosol paraffin and oil (determined at a rate of 95 l/min) from a relatively stretching of rolled into a tube samples FPP 15-1,5 tensile material axially coagulation (Fig. 1). For comparison was also tested a polypropylene filter material Eleflen, which specifications denoted in [7]. It can be seen, that the permeability of the material FPP grows faster, than Eleflen, that confirms our assumption.

Moreover, the temperature influence on the operational factors FPP lead to a change in the mechanical properties of the fiber layer and disruption of its structural parameters and hence to its destruction. This is evident from the experimental dependence of the relative ratio of penetration $K(t)/K$ duration of isothermal heating of samples of filter materials in a furnace at a temperature $t = 300$ °C (fig. 2).
<table><caption>Table 1. Key indicators FFP2 respirators Leaf DSTU EN 149: 2003</caption><thead><tr><th rowspan="2">Defined indicators</th><th colspan="2">The value of indicators</th></tr><tr><th>Factual</th><th>According to EN 149 for FFP2</th></tr></thead><tbody><tr><td>Penetration ratio for the test aerosol paraffin oil at a rate of 95 l / min, K, %<br/>- after delivery;<br/>- After the temperature exposure<br/>- After a mechanical action</td><td>2,5<br/>8,1<br/>4,6</td><td>No more 6</td></tr><tr><td>Permanent resistance to airflow at a flow rate of 95 l / min, R, Pa,<br/>- After delivery;<br/>- After the temperature exposure;<br/>- After a mechanical action;</td><td>90<br/>77<br/>86</td><td>No more 240</td></tr><tr><td>Test for flammability under t = + 800 °C</td><td>Ignites and continues to burn</td><td>Not flammable</td></tr></tbody></table>

As a result, during filter heat exposure increases the material suffers irreversible structure change. This decreases the protective efficacy of RPE as filtering properties of the material and has sustainable performance only up to 60° C. According to the State Standard DSTU EN 149: 2003, before the start of the test there is need some time to withstand the test samples in a chamber with a temperature of 70° C.

Therefore, harmonization of Ukrainian and European standards requires to develop a new type of respiratory protective equipment, whose technical specifications meet European standard. The problem is also caused by the fact, that workers, who have used to respirator "Leaf" in recent decades, are wary about new types of products, refusing to recognize their quality.

<figure><img src="image_3.png" /><figcaption>Fig. 1. Dependence of the coefficient of penetration by the oil mist from the relative stretching filter material folded into a tube during tension along the axis: 1 - 15 FPP - 1.5; 2 - Eleflen</figcaption></figure>

<figure><img src="image_4.png" /><figcaption>Fig. 2. Dependence permeation coefficient for the duration of oil mist filter materials isothermal heating the samples in an oven at t = 150°C: 1 - 15 FPP - 1.5; 2 - Eleflen</figcaption></figure>

To solve the problem it is necessary to follow the path of existing respirator "Leaf" modernization, which is going to substitute filtering material FPP.
Polypropylene filter materials have been used for a long time. However, safety features of them are enough low. This is due to the relatively large fiber diameter 3-8 microns and their large spread, significant unevenness of surface density, the surface electrostatic charge in contrast to bulk materials in FPP. Therefore, proposals for the improvement of technologies have been developed to improve the quality of the filter material.

The process for producing a fiber from melt consists the following steps: melting the polymer forming fibers from the melt, and cooling the fixing device on the receiving fiber (figure 3.). The fiber produced by extrusion. Extrusion - is to obtain products from polymeric materials by extruding the molten polymer through a forming head (nozzles) of the desired profile. The simplest and most common is a single screw extruder without degassing zone (Fig. 4).

<figure><img src="image_5.png" /><figcaption>Fig. 3. Block diagram of the installation for the production of polypropylene filter material: 1 - extruder; 2 - forming head; 3 - die; 4 - the pipeline; 5 - drums</figcaption></figure>

After loading the resin into the hopper, it transports to the hotter zones of the cylinder. With decreasing cutting depth and volume of the coil is reduced, which leads to the compression of granules which are melted. This improves the mixing of the polymer and makes better heat distribution in the melt. The final zone of the screw is a final melt homogenization. However, the process of material extrusion occurs outside the forming head [8].

<figure><img src="image_6.png" /><figcaption>Fig. 4. Extruding tool: 1 – hopper; 2 – the screw; 3 – cylinder; 4 – cavity for water; 5 – heater; 6 – forming head</figcaption></figure>
Molten polymer flows to and through the spinnerets holes a different diameter is applied to the zone where the fibers are drawn by hot air. Polymeric fibers entering the drum or conveyor, stretch out and intertwine crystallize, forming a filter layer. The main influence on its quality has a working temperature of the melt. Increasing melt temperature, viscosity decreases polypropylene facilitating thinning the fiber diameter, more uniform distribution of the fibers on the drum, but adversely affect the plant operation parameters. Thus, the long term effects high temperatures leads to slagging setup that interferes with normal feeding of the melt to spinnerets. Therefore results in a larger fibers, deterioration of their distribution on the drum width, the appearance of significant voids in the filter layer, for adhering fibers to the drum, or conveyor. Hence, to obtain high-quality filter material must adhere to a specific, sensitive to changes, temperature [9].

As a result, a long experimentation with temperature parameters a filter material has been developed, which is a nonwoven grid of thermally ultrathin polypropylene fiber diameter of 2...5 mkm, weighing 38 - 42 g/m2, supported on a layer of gauze (fig. 5.). Which in its performance is not inferior materials FPP. Laboratory studies proved its high protective characteristics (table 2).

<figure><img src="image_7.png" /><figcaption>Fig. 5. The structure of the propylene polymer material</figcaption></figure>

<table><caption>Table 2. Technical characteristics of polypropylene material</caption><thead><tr><td>Materials</td><td>Surface density, g / m2</td><td>Resistance to air flow in the filtration velocity of 1 cm / s, Pa</td><td>Breaking strength, N</td><td>The rigidity of the material, sm</td><td>Relative extension, %</td><td>The fiber diameter, microns</td><td>permeation coefficient for a test aerosol, paraffin oil, K%</td></tr></thead><tbody><tr><td>Eleflen - 40</td><td>38-42</td><td>4,2</td><td>6,0</td><td>6,0</td><td>50</td><td>2-4</td><td>0,6</td></tr><tr><td>Eleflen 40M</td><td>38-42</td><td>3,2</td><td>6,0</td><td>6,3</td><td>50</td><td>2-5</td><td>1,1</td></tr></tbody></table>

A pilot batch of 100 pieces dust mask "Standard" (fig. 6) was manufactured in NPP "Standard" and after laboratory tests showed a positive result, these products have been submitted to the test center (Lodz, Poland). As a result, it was found that the protective properties of the indicators developed by the half-mask defined after preliminary thermal exposure and modeling socks mode, comply with the requirements of EN 149 (Table. 3).
<figure><img src="image_8.png" /><figcaption>Fig. 6. Experimental samples of respirators</figcaption></figure>

<table><caption>Table 3. Key indicators respirator FFP2 standard in accordance with EN 149: 2003</caption><thead><tr><th>Defined indicators</th><th>Value indicators respirators prototypes</th></tr></thead><tbody><tr><td>permeation coefficient for a test - aerosol, paraffin oil at a rate of 95 l/min, K, %</td><td>0,6±0,1</td></tr><tr><td>- after delivery;</td><td>2,9±0,2</td></tr><tr><td>- After the temperature exposure</td><td>0,67±0,1</td></tr><tr><td>- After a mechanical action</td><td></td></tr><tr><td>Resistance to constant air flow at a rate of 30 l / min, R, Pa</td><td>18±0,4</td></tr><tr><td>- After delivery;</td><td>17±0,4</td></tr><tr><td>- After the temperature exposure</td><td>18±0,3</td></tr><tr><td>- After a mechanical action</td><td></td></tr><tr><td>Test for flammability under t = 800 °C</td><td>not flammable</td></tr><tr><td>The content of carbon dioxide in the air breathed, %</td><td>no more 1 %</td></tr></tbody></table>

**Summary.** It was found that FPP material of Leaf type respirator does not meet the parameters of DSTU EN 149: 2003 at a rate of dust penetration through the respirator filter after thermal and mechanical influences (for FFP2 class products - the average efficiency) and product flammability. Study showed, that increasing duration of exposure to heat the structure of the filter material undergoes irreversible changes. This leads to a decrease in the protective efficacy of RPE as filtering properties of the material FPP are characterized by stable performance only up to 60 °C temperature. Using polypropylene filter materials can replace FPP materials, which are indicators both meet European standards and does not contradict the traditional view of potential consumers.

References

[1] Cohen, H. J. Determining and validating the adequacy of airpurifying respirators used in industry Part I – Evaluating the Performance of a Disposable Respirator for Protection Against Mercury Vapor [Text], International Society for Respiratory Protection Journal of the International Society for Respiratory Protection. – 1984. – Vol. 2, Issue 3. – P. 296–304

[2] Basmanov P.I., Kaminsky S.L., Korobeinikova A.V., Trubitsyna M.E., Personal Protective Respiratory Protection. Reference Guide, 2002. - 399 p.

[3] Cheberyachko S.I., Analysis of filter materials used for the manufacture of personal respiratory protection. Development of ore deposits, 2001. - № 76. - p. 98-102.
[4] H.E. Mullins, S.G. Danisch & A.R. Johnston, Development of a New Qualitative Test for Fit Testing Respirators, American Industrial Hygiene Association Journal, Volume 56, Issue 11, 1995, DOI: 10.1080/15428119591016278

[5]. A.S. Ishchenko, Cheberyachko S.I., On transition to the European standards in the area of the particle of personal respiratory protection, Coll. Scien. tr. NSU, RIK NSU. - 2003. - P. 384-386.

[6] C.C. Chen, J. Ruuskanen, W. Pilacinski& K., Willeke Filter and Leak Penetration Characteristics Of a Dust And Mist Filtering Facepiece, American Industrial Hygiene Association Journal, Volume 51, Issue 12, 1990, DOI: 10.1080/15298669091370275

[7]. K.V. Polyakov, Yuri Brown, S.P. Tkachuk, Patant 22314 Ukraine, MKI3 A62 B23 / 02 Filtruyuchy element respiratora. Number 97031310.

[9]. Radchuk D.I. Influence of temperature on filtering properties of materials, Scientific Bulletin of NMU, 2009, № 10, p. 44-48.