Respirators filter canisters

Dust/mist filtering respirator Dust/mist respirator, or respirator with dust/mist filtering cartridge, respirator with organic vapor-removing cartridge and pesticide prefilter, respirator with canister approved for pesticides, or air-sup-plying respirator... 

The French developed the M-2 mask , consisting of 20 layers of muslin impregnated with Greasene and another 20 impregnated with Complexene . The mask had twin circular celluloid lenses and a weatherproof flap for rain protection, but no outlet valve or filter canister. The M-2 was followed by the Tissot mask , with a thin, moulded rubber facepiece incorporating eyepieces, a flapper-type rubber exhale valve and a flexible, fabric-covered hose running over the shoulder to a filter canister worn in a harness on the back. The Tissot mask also ducted air over the eyepieces to help demist them a feature still used in most present-day respirators. 

The Germans, like the British, also first used pads soaked in sodium carbonate and sodium thiosulphate, but then went on to develop a full face mask (which inspired the British Box designs). This was followed by a respirator, known simply as The German Mask , with a facepiece of natural rubber (later of oiled leather when rubber became unavailable), twin circular eyepieces with outer lenses of celluloid and inner lenses of coated gelatin, and a filter canister that screwed directly into the facepiece another design feature still used in most present-day respirators. 

After WWI, respirators followed the general style of elastomeric facepieces, with eyepieces/ visors and exhale valves, and filters connected by tubes or mounted directly on the facepiece. The first all-rubber, full-face respirator was issued to the Royal Navy in 1922 and the Army in 1924. The facepiece was moulded in natural rubber and its outer surface was covered in stockinette to aid the wicking out and surface evaporation of chemical agents. The respirator had two-inch diameter glass eyepieces and an expiratory valve fitted in the region of the nosepiece. The filter canister was mounted on the wearer s body and... 

The realization that it was more economical to have a single respirator design for all three services led to the introduction of the General Service (GS) respirator, familiar to all those who served in the Second World War. Over 25 million of these respirators were made in the UK alone, and issued to all Commonwealth forces and Civil Defence Corps. The GS respirator consisted of a rubber facepiece with stockinette covering, flat circular eyepieces, a diver-type outlet valve, an elastic webbing harness and a filter canister fitted with an inlet valve. The canister, worn on the body and attached to the facepiece by a hose, was filled with activated charcoal granules, with a wool-asbestos mixture added later, and impregnated charcoal added even later. 

There are three respiratory effects. First, inhalation resistance is imposed by the filter canister, inhalation valve and, to some extent, the airflow pattern. Secondly, exhalation resistance is imposed by the exhale valve and to some extent the exhale valve deadspace design. Thirdly, the internal volume of the respirator increases the respiratory deadspace, which can cause build-up of carbon dioxide. 

The most important perceptual-motor effects of respirators are on vision and speech intelligibility. It is common experience that respirators restrict the visual field, depending not only on the eyepiece shape, size and eye-relief (distance from eye to eyepiece), but also on intrusion of filter canisters and other components into the visual field. Respirators can also impair visual acuity if the eyepieces are not well-designed or become misted. 

The ability to use equipment while wearing a respirator has already been mentioned. The problem is that the respirator s bulk can obstruct the wearer s access to other equipment, particularly equipment that comes into direct contact with parts of the respirator. The main respirator components involved are the eyepieces/visor and the filter canister(s), and the main pieces of equipment are shoulder-held and fired weapons, optical equipment, such as weapon sights, binoculars, night vision aids, and communications equipment. 

Air leakage measurements use a system of controlled negative pressure in which air is pumped out of the respirator to create a fixed negative pressure (usually 1 in water gauge) and the airflow need to maintain this pressure is measured. The airflow is taken as the same as the leakage rate into the respirator. The method requires wearers to hold their breath and the filter canister to be blanked off (otherwise, air will leak through the filter). 

Respirator with... filter Recommended when working with harmful powders which, even in limited quantities, can give off harmful vapors. The respirator + filter consists of a gas-absorbing canister and a dust mask. 

Full Face Respirator. A rubber or plastic facepiece that covers the eyes, nose and mouth and has replaceable filter canisters. 

The company maintains a respiratory protection schedule by job and working condition. This schedule is provided to each authorized and trained employee. The schedule provides the following information on job/working conditions, work location, hazards present, type of respirator or SCB A require4 type of filter/canister required, location of respirator or SCB A, and filter/cartridge change out schedule. 

Full face respirators of rubber or plastic cover the entire face from just below the hairline to beneath the chin and are held in place with an adjustable head harness. Air is drawn through one or more approved filter canisters and, where fitted, inhalation valves. It may be used for... 

Air line breathing apparatus Canister respirator Self-contained breathing apparatus Canister respirators with particulate filters Cartridge respirator General purpose dust respirators High efficiency dust respirators... 

Dust/mist masks, prefilters, canisters, filtering and vapor-removing cartridges, and a few cartridge respirators are disposables. They cannot be cleaned, and they should be replaced often. 

Seal the entire respirator in a sturdy, airtight container, such as a zip-closable plastic bag. If you do not seal the respirator immediately after each use, the disposable parts will have to be replaced more often. Cartridges, canisters, prefilters, and filters will continue to collect impurities as long as they are exposed to the air. 

Air-purifying respirators contain cartridges (or canisters) that contain an adsorbent, such as charcoal, to adsorb the toxic vapor and thus purify the breathing air. Different cartridges can be attached to the respirator depending on the nature of the contaminant. For example, a cartridge for particulates will contain a filter rather than... 

Figure 8. The CompPac ventilator (photograph courtesy of Smiths Medical International Ltd.). This portable pneumatic device can be driven from a variety of power options, including an internal battery, and uses compressed ambient as the ventilating gas. This is filtered through a conventional CBRN respirator canister. The driving gas can be enriched with bottled oxygen given an endurance of over four hours ventilation in a contaminated zone...

A. Filtration. In a small scale emergency, water may be decontaminated by running it through a spare unused respirator canister, provided that the flow rate is such that the water emerges drop by drop any water coming through at first faster than this should be discarded. No more than 5 liters should be filtered with one canister. The canister cannot be used on a respirator after being used for this purpose. 

The effectiveness of the air purifying respirator depends on choosing the proper filter, cartridge or canister for the type of exposure present. Air purifying respirators rely on the use of activated charcoal or other chemical-specific filters, which remove gases and vapors, or filters which remove particulates such as dusts. Others utilize a combination of both. 

Air-purifying full-facepiece respirator with chemical canister and appropriate filter (gas mask with filter)... 

GmFAglOO 50 Any air-purifying, full-facepiece respirator (gas mask) with a chin-style, front- or back-mounted acid gas canister having an NlOO, RlOO, or PIOO filter. See Table 4 (page xxv) for information on selection of N, R, or P filters. 

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