Respiratory protection filter
Respiratory protection filters ( respiratory filters or filters for short ) protect the wearer from dangerous substances (gases, particles of solid and liquid substances). They are used in combination with respiratory masks for occupational safety , fire brigade , medicine and the military .
Filter types
Respiratory protection filters are divided into two categories, particle filters and gas filters. There are also combination filters that offer protection against gases and particles.
Particle filters come in three different classes (P1, P2, P3). In the case of filtering half masks, the classification is based on the total leakage and otherwise on the maximum excess of the workplace limit value . These maximum limits are higher for full face masks than for half masks. Particle filters only protect against particles, not against gases and vapors.
Gas filters are divided into different types of gas filters depending on the substance group (e.g. "ammonia", "organic gases and vapors", "low boilers"). There are also three different performance classes here. Gas filters only protect against gases and vapors, not against particles.
Combination filters consist of a gas filter and a particle filter. They are used when gases or vapors and particles (suspended matter) occur at the same time (e.g. during fire fighting, paint spraying, spray gluing).
Filtering half mask
Type A gas filter
Combination filter A2P3
Cross section through combination filter (bottom fleece layer as particle filter, top activated carbon filter as gas filter)
An NBC protection filter and a particle filter
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Conditions of use
Before using respiratory protection filters, the composition of the ambient air must be known in terms of both the type and amount of pollutants and the oxygen content. This results in the selection of suitable respiratory protection filters (for an example of a filter list see under web links).
The following conditions must be met for the use of filter breathing apparatus, otherwise self-contained breathing apparatus (e.g. compressed air breathing apparatus or compressed air breathing apparatus ) must be used:
- Existing pollutants must be known in terms of type, properties and composition.
- The oxygen content of the inhaled air must be more than 17% by volume.
- Gas filters may only be used against gaseous pollutants - never against particles.
- Particle filters may only be used against particulate pollutants - under no circumstances against gases or vapors.
- If gases and particles occur at the same time, or if particles can release gases, combination filters or, if the design of the respiratory protective device allows, a gas and particle filter that can be combined one after the other should be used.
- The maximum permissible pollutant concentration for the respective filter class must be observed.
Labelling
The suitability of a gas filter for a group of substances is indicated on the filter by means of a colored ring and an identification letter. The color code for particle filters is uniformly white. Combination filters have all the colored rings and letters of the area against which they protect. The capacity (class) of a filter is also indicated by digits from one to three. In the case of combination filters, it is specified individually for each code letter.
Type
In Germany, the following identification colors and letters are standardized. Either the entire filter body can be colored in the identification color or, what is more common, a colored ring can be applied to the filter body.
| Identification color | Type | scope of application |
|---|---|---|
| brown | A. | Organic gases and vapors with a boiling point> 65 ° C |
| brown | AX | Low-boiling organic compounds (boiling point ≤ 65 ° C) of the low-boiling groups 1 and 2 |
| Gray | B. | Inorganic gases and vapors e.g. B. chlorine , hydrogen sulfide , hydrocyanic acid |
| yellow | E. | Sulfur dioxide , hydrogen chloride and other acidic gases |
| green | K | Ammonia and organic ammonia derivatives |
| blue | NO | Nitrous gases ( nitrogen oxides ) e.g. B. nitric oxide , nitrogen dioxide |
| red | Ed | mercury |
| black | CO | Carbon monoxide |
| orange | reactor | Radioactive iodine and radioactive iodomethane |
| violet | SX | Gases and vapors according to the manufacturer's instructions |
| White | P | Particles |
Filter classes (absorption capacity)
Each filter also bears an indication of the filter class, since the filters are divided into mainly three classes according to adsorption capacity (1: low to 3: high). The class indicates how much the occupational exposure limit (formerly Maximum Workplace Concentration / MAK) may be exceeded.
| Filter class | maximum permissible gas concentration in the air supply to the filter |
|---|---|
| class 1 | 1,000 ml / m³ (0.1 vol%) |
| 2nd grade | 5,000 ml / m³ (0.5% by volume) |
| Class 3 | 10,000 ml / m³ (1.0% by volume) |
Type AX gas filters:
there is no classification, but different maximum periods of use, which depend on the maximum concentration and the substance (classification according to the boiling point ).
| protection against | maximum permissible gas concentration in the air supply to the filter |
maximum duration of use |
|---|---|---|
| Group 1 substances | 100 ml / m³ (0.01 vol%) | 40 min |
| 500 ml / m³ (0.05 vol%) | 20 min | |
| Group 2 substances | 1,000 ml / m³ (0.1 vol%) | 60 min |
| 5,000 ml / m³ (0.5% by volume) | 20 min |
For filters of the types NO, Hg, CO and reactor, the manufacturer's information on duration of use and concentration must be observed. So may
- Type NO filters for a maximum of 20 minutes and
- Hg type filters can be used for a maximum of 50 hours .
Identification of filters in the Bundeswehr and the extended disaster control
The filters from the area of the Bundeswehr are not named and labeled according to the above labeling system . These filters are painted olive and have a designation that describes the properties of the filter body such as: B. "FE 55 NM" (filter element 55, not magnetizable). Filters against carbon monoxide are marked with the letters “CO” instead of the number “55”. The tests of the filters do not correspond to the above filter types either; instead, certain chemical warfare agents are used for testing ( cyanogen chloride , hydrogen cyanide , chloropicrin ). This also applies to the successor model, the filter for the M2000 A protective mask and the filter for the S10 protective mask . The filter of the extended disaster control KS 80 described below is also used.
In the area of extended disaster control , the combination screw-on filter "KS 80 FE NM" (filter insert, chemical-biological mask; NSN 4240-12-180-8400; imprint "BUND KS 80": federal property, combination Screw filter, year of development 1980; sheet metal stamping “FE NM” = filter element not magnetizable) for use with the M 65 Z NBC protective mask. The entire filter body is colored gray (identification as gas filter type B - class 2) and provided with a white (particle filter - class 3) and an orange (reactor filter) band for identification. In addition, it still fulfills the requirements as gas filter A and E. It is therefore a combination filter A2B2E1-Reactor-P3.
Service life (service life)
The service life of the respiratory filter depends on the load.
- The end of the useful life of gas filters or combination filters that have been used against gases can be recognized by the smell, taste or irritation when inhaled.
- The end of the useful life of particle filters or combination filters that are used against particles can be recognized by the increase in breathing resistance (inhalation resistance).
- Particle filters used against radioactive substances, spores, bacteria, viruses and proteolytic enzymes should only be used once.
An expiration date is printed on all filters. At this point at the latest, the filters can no longer be used as protection against dangerous substances. Particle filters usually have a shelf life of ten years, and gas filters five years if unopened. Filters that have already been opened, but not sealed, must be disposed of or may only be used for training purposes.
Mask and filter designs
There are many types of masks with different filter models, depending on the intended use, duration of use, type of pollutant, etc.
- Filtering half masks are mask and filter in one. No filter can be replaced here; they are completely disposed of after use or when the filter is exhausted. Advantages: comfortable to wear, light, relatively large filter surface, very hygienic. Disadvantages: somewhat more expensive to use, not suitable for gaseous pollutants.
They are also available with an exhalation valve, which is highly recommended, as the breathing resistance is significantly lower and the moisture in the breath can escape through the valve. Also used in the medical field to protect against infections.
- Half masks
They consist of a mask wearer, usually made of rubber or silicone, and cover the mouth and nose area. One or two filter cartridges can then be attached to this body. The filters are available with standardized round threads, but also with manufacturer-specific fastenings. Advantages: also suitable for gaseous substances, lighter than a full face mask, relatively inexpensive to operate. Disadvantages: has to be cleaned accordingly, heavier than disposable masks, usually not as good a field of vision as disposable masks (filters disturb the view downwards), you may need additional eye protection (different with full face masks).
- Full face masks
They are commonly known under the synonym " respiratory protection mask ". It has the following differences to the half mask: It also encloses the eye area, even better tightness, of course less wearing comfort (heavier, narrowed field of vision, more perspiration). It is mainly used for heavy respiratory protection (fire brigade), highly toxic or highly infectious substances.
- Blower-assisted respiratory protection
This consists of a so-called head section and a separate fan with a battery, which is connected to the head section by means of a hose. The blower sucks the breathing air through one or more attached filters (mostly with standardized round threads) and blows it into the head part where it is distributed and inhaled. No pollutants can penetrate due to the overpressure. Advantages: very comfortable to wear (little skin contact, cooling air, no breathing resistance - so no examination of the wearer necessary - mostly large field of vision). Disadvantages: relatively high acquisition costs, increased filter requirements due to the additional air flow. Particularly advisable for long periods of wear.
application areas
fire Department
Combination filters (especially A2B2E2K2-P3) are common in the fire service. This results from the fact that it is often not possible to determine exactly what pollutants are in the air in the event of a fire. However, since the above-mentioned conditions of use for wearing filter devices often cannot be met or no specific assessment of the pollutants can be made, respiratory protection independent of the ambient air is worn by the emergency services in case of doubt. Typical applications for wearing filters are post-fire extinguishing work and ABC missions .
Breathing filters are supplied with a round thread connection for normal pressure masks. For overpressure masks with screw connections (thread M45x3) there have been filters with this metric thread connection for some time.
The legal basis for use under respiratory protection by German fire brigades is fire service regulation 7 (respiratory protection).
With a few exceptions, such as radiation protection, respiratory protection filters are not used by the fire brigade in Austria , as the risk of incorrect use is classified as too great.
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If dust, smoke or vapors are released during activities and there is no effective extraction of these hazardous substances, the employer must take further measures. One possible measure is the use of respirators. Here are some examples:
- For mechanical processing z. For example, drilling, milling, grinding and sawing releases dust.
- Fibers occur when laying or removing insulation material.
- Smoke is generated during welding work.
- When handling chemicals and in manufacturing processes, harmful gases can escape or arise.
In order to filter these hazardous substances out of the breathing air, respiratory protection masks with particle filters or particle-filtering half or full masks are used. In Germany, DGUV rule 112-190 (use of respiratory protective equipment) can be used to help with the implementation of state occupational health and safety regulations and regulations of the accident insurance carriers.
Security of old filters
Respiratory protection filters that have exceeded their expiry date usually no longer guarantee protection. Aside from that, older type filters can pose other risks. Asbestos was used in NBC protection filters in Germany until 1969, in some other countries it was used much longer. However, the filters are designed in such a way that the asbestos cannot be inhaled, but if the filter is subjected to a violent shock, the asbestos fibers can loosen from the filter material. Another risk is that the material that prevents the activated charcoal from being inhaled will break down over time and the activated charcoal will be inhaled. This can lead to eye and respiratory diseases.
Web links
Individual evidence
- ↑ a b c Brochure "Respiratory Filters" from MSA Auer ( PDF )
- ↑ In 3 steps to the right respiratory protection (PDF; 200 kB) for 3M filters
- ↑ ( Page no longer available , search in web archives: Federal Office for Defense Technology and Procurement, technical delivery conditions 4240-0017: screw filter, not magnetizable for NBC protective mask ) (PDF; 222 kB)
- ↑ ( Page no longer available , search in web archives: Federal Office for Defense Technology and Procurement, Technical Delivery Conditions 4240-0065: Filter, non-magnetizable for NBC protective mask M2000 ) (PDF; 200 kB)
- ↑ Technical delivery conditions 4240-0063: Mask filter for protective mask S10 for aerial photo evaluation staff. Federal Ministry of Defense, accessed on February 21, 2020 .
- ↑ a b Disaster control service regulation 120: Equipment of all specialist services, description of the filter: Part A: ABC equipment of all specialist services, Section 6.1.1 (p. 143ff.), Federal Office for Civil Protection, 1988 (PDF; 24.7 MB)
- ↑ DGUV rule 112-190 (PDF; 2.2 MB)