4. Essential elements of a design of filtering self-rescuers

Filtering self-rescuers are designed to protect respiratory apparatus, eyes and head skin from aerosols of various nature, fumes and gases of dangerous chemical substances, red-hot particles (sparks, hot splashes) and short-term influence of the open fire. According to such purpose there are essential elements of filtering self-rescuers: anti-aerosol filter, absorbing element, front part completely covering a head and a neck of a person. All elements of the self-rescuer should be ignition proof.

The most complex element is absorbing system of the self-rescuer, especially for small-sized products. On the one hand, it is required to provide protection from the wide range of fumes and gases of various physical and chemical natures, on another - opportunities for the developer are essentially limited by weight and size of a product.

Choice of absorbers for absorbing systems of self-rescuers lies within possible conditions of their use and is considerably different from similar procedure for PSERA used in labor safety system when type of acting substance or group of substances is known. Self-rescuers intended for use at man-caused disasters, terrorist acts, fires should have universal absorbing system. But any absorbing element of filtering, especially small-sized PSERA, cannot provide absolute protection from all dangerous fumes and gases, therefore it is necessary to define a reasonable and sufficient degree of universality of self-rescuers.

Analyzing possible situations with necessity of self-rescuers use we see that in most cases products of A, B, Е, K models can provide sufficient degree of universality.

Rather burning issue at design stage of self-rescuers is protection from carbon monoxide. Traditional use of hopcalite catalysts with appropriate dehumidifiers in absorbing systems does not allow to reach sufficient protective properties in products weighing up to 0,2-0,25 kg. Thus, in such way to provide protection from carbon monoxide using current techniques does not allow to develop portable universal self-rescuers intended for everyday carrying by the user in ready-to-use state.

In our opinion, mentioned problem can be solved using complex approach that consists of the following: portable self-rescuers should be used in situations when CO concentration does not exceed some permissible values. Facilities with higher concentrations of carbon monoxide during fires should be supplied with large-sized PSERA with high protective properties against CO. To implement such approach it is required to define values of permissible concentrations of carbon monoxide when portable self-rescuers can be used.

Results of evaluations of CO concentrations received in the USA after examination of more than 200 real fires of various complexity show that in 90 % of occasions concentration of carbon monoxide did not exceed 0,7 mg/l, in 5 % of occasions was 0,7-1,0 mg/l, in 3 % of occasions - 1,8-6,0 mg/l.