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GUIDE FOR SELECTION AND USE OF
Using Table 1, a list of respiratory protective devices shows the type of equipment which meets the minimum requirement FILTERING DEVICES
of the protection factor of 50 if used correctly. This applies It is the purpose of this brochure to show how people can e.g. for a half mask plus P3 fi lter.
be protected against health risks ensuing from harmful sub- 1)Values and terms of calculation have been taken from CEN report 529. Ad- stances in the ambient atmosphere and how they can select ditional national and local regulations must be followed.
Example 2
The selection of the respirator is dependent on the Question: The maximum allowed concentration of contami-
nature and extent of the hazard, the work requirements and nant with full face mask and B2 fi lter? conditions, and the characteristics and limitations of the respi- 0.5 ppm (MAK according to German regulations) The following circumstances have to be checked fi rstly:• What are the contaminates? Full face mask gives a nominal protection factor of 2000.
Full face mask + B2 fi lter gives a nominal protection factor of • What is the applicable Occupational Exposure Level • Are the contaminants gaseous or particulate or a combina- 2000 x 0.5 ppm = 1000 ppm = 0.1% chlorine by volume.
• Do the contaminants have adequate warning properties of The same method is used either for particulate or gaseous • Are the contaminants immediately dangerous to life and hazards. Where contaminants are present in both forms, the nominal protection factor must be established for each one • Does the atmosphere contain enough oxygen? (see local separately. For the selection of fi ltering devices, the higher one • Is additional protective equipment required? It should be borne in mind that the performance predicted by 1. Calculation of the protection factor necessary1
the Nominal Protection Factor can only be expected of a res-piratory protective device which is correctly worn and which The selection of the most suitable type of equipment for particu- has been properly maintained. When a face-piece is available lar circumstances requires understanding of the hazard against in more than one size, it is important the best fi t for the in- which protection is required as well as an understanding of the dividual is worn. Facial hair, when present between the face limits of protection of the equipment available. It is necessary and face-piece seal will substantially increase the leakage with to both the concentration and occupational exposure limits of harmful contaminants that are likely to be encountered in air. An OEL is the concentration of an airborne substance, aver-aged over a reference period, at which, according to current Nominal protec-
knowledge, there is no evidence that it is likely to be injurious tion factors2
to employees if they are exposed by inhalation, day after day, Particle fi ltering devices
Example 1
Question: How to calculate the protection factor required?
The minimum protection factor required is: Gas fi ltering devices
As an aid to the selection of respiratory protective equipment, the term “Nominal Protection Factor” has been introduced into these guidelines for each type of equipment. The NPF is derived from the maximum permitted inward leakage (%) of the whole device stated in certain standards, or the 4)special guidelines according to local regulation apply inward leakage fi gures from the relevant standards of different components.
Example 4
Nominal Protection factor is defi ned as, NPF = 1/PIL x 100, where PIL = permitted total inward leakage (%).
Example 3
Question: What is the NPF of a fi ltering half mask, permit-
ted total inward leakage = 22%
Answer: Nominal protection factor = 1/permitted total
inward leakage = 1/22 x 100 = 4.53
A fi lter with the above mentioned colour code is suitable for: gases and vapours of organic compounds with a boiling point greater than 6500C covered by fi lter class 2 and; 2. Selection of the fi lter
inorganic gases and vapours e.g chlorine, hydrogen sul-phide, hydrogen cyanide up to concentrations covered by Contaminants are encountered in different forms, presenting particles up to concentrations covered by fi lter class 3 either a particulate or gaseous hazard, and therefore different fi lters are required to protect against particles, specifi c gases, or a combination of both. A particulate hazard may include dusts, fi bres, fumes, mists or micro-organisms. A gaseous hazard may consist of gases or vapours. It is important that the appropriate type of fi lter is selected for the form of con- The following table shows the colour coding of respiratory fi l- Colour code Filter Main fi eld of application
3. Warnings
3.1. Do not use any fi ltering respirator: in oxygen defi cient atmosphere (see local legislation); In poorly ventilated areas, or in confi ned spaces such as tanks, small rooms, tunnels or vessels (unless the con- Reac- Radioactive iodine4 including radio- fi ned space is well ventilated and the concentration of toxic contaminants is known to be below the upper limit recommended for the respirator); in atmospheres where the concentrations of toxic con- Contaminant
Colour code
taminants are unknown or are an immediate hazard to life or produce an immediate irreversible debilitating effect on health; at concentrations of hazards greater than the fi lter class capacity as stated on the respirator label.
if a substance has poor warning properties, like odour, taste or irritation such as Aniline, Benzene, Carbon Mon- 3.2. Immediately leave the area and then remove the respira you sense irritation, smell or taste contaminants; there are no harmful particulate substances (i.e. dusts, mists or fumes) present when only gas/vapour fi lters are fi tted to the respirator and no harmful gase/vapours are present when only particulate fi lters are fi tted; the respirator selected properly fi ts the wearer.
4. Filter Life
The period of use of a respiratory fi lter depends on its size (class) and on the conditions of use. Air consumption by the user, air humidity, air temperature and the concentrations and combinations of the toxic substances involved all infl uence the life time of the fi lter. For this reason, a precise period of use can only be specifi ed if all these factors are known in advance. Gas fi lters generally show the user that their capacity is exhausted by way of a perceptible odour. Further use will certainly result in irritation of the mucous membranes. For safety reasons, fi lters and special fi lters used to protect against odourless gases must be replaced according to the special guidelines Continual loading of particulate fi lters causes them to clog up and the breathing resistance increases noticeably. The user can then leave the danger area at the correct time. Depending on the mixture of toxic substances, combined fi lters indicate that their capacity is becoming exhausted, either by an odour, or by increased breathing resistance.
5. Filter recommendation
Please note the nomenclature for the fi lter recommendations are as follows: Gas fi lter or particle fi lter required; if the substance is also present in particulate of gaseous matter, a combined fi lter (A-P) is required, e.g. 1-octene.
Contaminant
Colour code
5)SCBA - Self controlled breathing apparatus Contaminant
Colour code
Contaminant
Colour code
Contaminant
Colour code
Contaminant
Colour code
Contaminant
Colour code
Contaminant
Colour code
Contaminant
Colour code

Source: http://www.engineeringinfo.co.za/sites/default/files/downloads/pdf_files/guide-for-selection-and-use-of-filtering-devices-46.pdf