Filtering Respiratory Devices

Filtering respirators reduce the concentration of contaminants in the breathing air. Depending on the type and efficiency of the filter and the nature of pollutants, the inhaled air can contain variable residual concentrations of contaminants. 

Therefore, a suitable choice and the exact observation of use restrictions are essential to achieve an optimum of safety during use. 

Generally, filtering respiratory devices are only to be used when the oxygen content of ambient air is at least above 17%. 

In addition, the chemical nature of the contaminants and the order of magnitude of their concentration must be known. 

Depending on the physical condition of the chemicals, filtering respirators are divided into 

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Functional characteristics of the employees. The wearing of respiratory devices, except for simple dust masks, can be both physically and psychologically demanding. Even a cartridge respirator without any requirement for a hose connection can be restrictive, the more so in the presence of any obstruction to breathing by a clogged filter. Indeed, to some sus-... 

The technology used by the military has been adopted by industry to provide protection to workers against hazardous vapors and gases that may be encountered in certain industrial processes. As with the military, this involves individual protective respiratory devices, air treatment filters, and protective clothing. Depending upon the nature of the hazard, the carbons may be impregnated to enhance their ability to remove the toxic species. 

Depending on how the air is suppHed, respiratory devices are divided into filtering devices or ambient air-independent devices (see Fig. 6.27). The latter comprise suppUed-air respirators and self-contained breathing apparatus, both of which are used in an oxygen-defident atmosphere. 

Section 6.9). The filters for coarse dusts (see Fig. 6.33a), which are quite commonly used in some industrial sectors, do not meet the general requirements for respiratory devices therefore they are not to be used against hazardous particles. Whereas particle filters of type PI and FFPl are not to be used for protection against aerosols, the higher filter classes can be used against fog and droplet-aerosols. 

In analogy to respiratory devices for working situations, the respirators for escape are divided into filtering and seU-contained devices (see Fig. 6.46). 

Fig. 6.48 Respiratory devices for escape, (a) Respiratory fiiter for escape as a half mask (b) respiratory hood for escape with a combined filter.

Respiratory protection is of primary importance since inhalation is one of the major routes of exposure to chemical toxicants. Respiratory protective devices (respirators) consist of a facepiece connected to either an air source or an air-purifying device (cartridge or filter). Respiratory protective equipment can be categorized into three types ... 

Once samplers have been trained, they need to be properly equipped. A set of five constant flow-samphng pumps with battery chargers and the needed respiratory collection devices (cyclones) cost around 5,000 to 6,000. These ptunps, equipped with the proper collection filter or device, can be... 

Respiratory protective devices - Powered filtering devices incorporating a helmet or a hood - Requirements, testing, marking. Superseded BS EN 146 1992... 

Compressed airline system a facepiece or hood is connected to a filter box and hand-operated regulator valve which is provided with a safety device to prevent accidental complete closure. Full respiratory, eye and facial protection is provided by full-facepiece versions. The compressed air is supplied from a compressor through a manifold or from cylinders. 

Lead Acetate Solution (Caution Use gloves and goggles to avoid contact with skin and eyes. Use an effective fume-removal device or other respiratory protection.) Activate 50 to 60 g of lead (II) oxide by heating it for 2.5 to 3 h in a furnace at 650° to 670° (cooled product should have a lemon color). Boil 80 g of lead acetate trihydrate and 40 g of the freshly activated lead (II) oxide with 250 g of water in a 500-mL Erlenmeyer flask provided with a reflux condenser for 45 min. Cool, filter off any residue, and dilute with recently boiled water to a density of 1.25 at 20°. Add 4 mL of water to 1 mL of the lead acetate solution, and filter. 

Air sampling for occupational exposure to pesticides normally consists of measurement of pesticide concentrations in the worker s breathing zone, with a portable air-sampling pump and a sampling train which includes some type of collection device. The latter device, or sampling media, selected are based on the physical and chemical properties of the compound to be measured. Field workers may be exposed to chemical vapors, solid particulates or water-based aerosols. Examples of sampling media include membrane filters, sorbent tubes, polyurethane foam and charcoal. A discussion of pesticide exposure provides a useful review of methods for respiratory exposure measurement (Nigg etal, 1990). 

Most chemicals used by people become airborne either by volatilization or from being blown as aerosols or particulates by air moving devices and wind. The hazards of particulate matter are, to a great extent, determined by their size. Particles larger than 10 pm diameter are filtered out in the upper respiratory tract and expelled. All particles with a diameter of 10 pm or smaller (PM 10) reach the lungs and are harmful. Particles with diameters of less than 2.5 pm (PM2.5) are particularly dangerous because they reach deep into the lung tissue. This subject was discussed in Section 5.3 and is examined in more detail in the respiratory effects chapter (Chapter 17). 

Fig. 6.38 Selection of various power-assisted respiratory filtering devices, (a) Respiratory hood (b) light respiratory hood (c) respiratory helmet ...

EN 405 2001 Respiratory protective devices -Valved filtering half masks to... 

Brochocka A, Makowski K and Majchrzycka K (2012), Penetration of different nanoparticles through melt-blown filter media used for respiratory protective devices . Text Res J, 82(18), 1906-1919. 

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