The probability of non-failure operation of the self-rescuer pays off on a known parity 3/:

РО(t) = РВН(t)* РИЗН(t)* РПР, (2)

where: РВН(t), РИЗН(t), РПР - Probabilities of absence sudden, jobing refusals, accordingly.

Forecasting of values of the probabilities entering into parities (1) and (2) for each con-crete self-rescuer represents an independent problem. Within the limits of present clause it is represented expedient to state only approached estimation of size RN. At an assumption, that hit of the person in a dangerous zone equiprobably for all days of week and time of day as size РН can be accepted a share of time during which means of protection is within reach the person. For example, if the self-rescuer is stored in a study, duration of working week makes 41 hour, thus during work the person does not depart far from the workplace, Рн = 41/168 = 0,24. Such approach is rather approached. Nevertheless it allows, in our opinion, to give a tentative estimation of efficiency of use of a product of class S. Even for an ideal product with absolute protective properties (RIZN (t) =1) both accomplished (perfect, absolute) stroging and operational characteristics (Рвн (t) =1, RPR=1) the problem of maintenance of protection will be solved no more than on 10-30. At the same time for a product of M-class (constantly is within reach, РН=1) at maintenance, for example, a 70 percent level of protective properties (RIZN (t) = 0,7) and same values RVN (t) and RPR the problem of protection is solved on 70%.

It is necessary to note, that comparison of the resulted figures should not lead to a conclusion about necessity of maintenance of the population only products of a class of M. Most preferably to use both of a kind of products: class S - there where it is possible and products of a class of M - in all other cases.

According to the classification resulted in figure, self-rescuers of class S are divided on special filtering, universal filtering and universal isolating. In a basis of such division the following principle lays: if the kind of danger and the characteristic of the amazing factor are known, the population, endanger to this kind, it is necessary to provide with special self-rescuers. For example, if there is a threat of emergency emission on the settlement located near to chemical object, only organic substances it is expedient to use the self-rescuers intended for protection against this group of substances.