In these rules are fixed the maximum values ​​allowed for both the initial penetration through the dust filters (Grades P1, P2 and P3 ) for both the loss attributable to the inward face and possibly other components. Made clear , therefore, that within the facial and ‘ still present a certain concentration of pollutant due to both the penetration through dust filters both to the losses attributable to the inward face and other components, you stabiscono the following definitions :
protection factor (PF ) and ‘ the relationship between the concentration of the pollutant in the ambient air and the inside of the face , the height of the respiratory tract of the user; nominal protection factor ( FPN ) and ‘ the value of the protection factor when the penetration through the filters and losses inward assume the maximum values ​​allowed by the rules ; protection factor of Operations ( FPO ) and the value on the basis of experimental data and prudential considerations ; is attributed to the protection factor for the choice of a respirator for use in the work environment .
It seems useful to further clarify the following:
the protection factor and ‘ by definition the parameter that expresses , in general, the entities’protection that a respirator offers the user ; the nominal protection factor and ‘ the value of the protection factor which must be guaranteed at the time of certification by the control bodies , with laboratory tests standardized and therefore reproducible ;
the protection factor and operating ‘ factor value of security to use in practice
operational work environment : this value – always less than or at most equal to the nominal protection factor – has the purpose of keeping cautiously into consideration the problems arising from the specific diversity ‘ concerning the various work environments , by the requirements of mobility’ operator , and the accuracy with which ‘ put on the respirator , etc. . ; what ‘ is especially true for devices which are associated with the most’ high values ​​of protection.
For the different types of respirator is provided below the values ​​of the FPN and those of FPO :
Respirator                                                                                                         FPN              FPO
_________
Half mask with P1 filter (or filtering facepiece FFP1 )                                          4                     4
Half mask with filter P2 ( FFP2 or filtering facepiece )                                       12                  10
Half mask with filter P3 ( or filtering facepiece FFP3 )                                       50                 30
Full mask with P1 filter                                                                                              4                    5
Full mask with filter P2                                                                                             20                15
Full mask with filter P3                                                                                         1000            400
Elettrorespiratore Class 1 for use with a helmet or
cap ( THP1 )                                                                                                                 10                 5
Elettrorespiratore Class 2 for use with helmet or
cap ( THP2 )                                                                                                                  20              20
Electrorespirator class 3 for use with helmet or
cap ( TIHP3 )                                                                                                               500          100
Electrorespirator class 1 for use with mask
( TMP1 )                                                                                                                          20            10
Electrorespirator class 2 for use with mask
( TMP2 )                                                                                                                        100         100
Electrorespirator class 3 for use with mask
( TM3 )                                                                                                                           400      2000
The report that provides the maximum limit of exposure to a certain pollutant in function of the operating protection factor of the respirator and the exposure limit value adopted for asbestos and ‘the following :
maximum exposure limit = FPO x VLE
where with VLE and ‘ indicated the exposure limit value adopted .
If we consider eg crocidolite (VLE fibre/cm3 = 0.2 ), the protective factor operating on the half mask with combination filter P3 indicates that such a respirator will provide ‘ user a guarantee of protection up to a concentration of 6 fibre/cm3 . The use of a full face mask with P3 filter , or a Electrorespirator class 3 for use with mask, potra ‘ instead provide up to a concentration of 80 fibre/cm3 .
For the reclamation work , during which they are usually reached high concentrations of
Asbestos fibers are normally favorites ( also in relation to more ‘ favorable microclimatic conditions for the user ) and the turbo devices THP3 TMP3 . If these prove to be insufficient for the guarantee of protection which must be achieved must then be used , as mentioned earlier , insulating respirators with which can ‘be reached a value of the factor of protection operating equal to 1000 .
For occasional work ( generally limited maintenance or repairs ) which is not associated with a high release of fibers , the use of half-mask with a P3 filter provides sufficient guarantees ( without being unnecessarily oversized ) in relation to any incident that may result in significant – but temporary – concentrations of asbestos fibers into the environment.