Parovydeleniya and gassing
Parovydelenpya and gassing which affect the PA man in modern industry are extremely diverse.
If hazardous gases are numerous and vary in their properties, the noxious fumes in many respects similar to each other (except for mercury vapor). They usually represent a pair of highly volatile liquids. This is usually hydrocarbons, alcohols and esters of fatty and aromatic series and their derivatives.
Mercury - the only metal which significantly evaporate at room temperature. Speaking of mercury vapor, we mean a pair of metal really. All other metals, notably volatile only at relatively high temperatures, while oxidized by air, forming oxides - solids. These latter into the air as tiny particles, which create smoke - aerosol. Zinc evaporates, forms zinc oxide - foundry fumes, lead - lead oxide, arsenic - arsenic and arsenious anhydride, etc. Pairs of metals should be viewed as aerosols, consisting of a mixture of metal oxides and tiny metal particles.
Harmful industrial gases are classified by the nature of their actions on human rights and are divided into poisonous, asphyxiating, irritant and narcotic. In each group there are more or less toxic gases. The degree of toxicity is characterized by the maximum permissible concentration of gases in indoor air at long stay in them.
Maximum allowable concentrations of toxic gases, vapors and aerosols in the air of industrial premises regulated by the SN 245-63.
On the toxicity of harmful gases, fumes and aerosols of several conditionally can be divided into the following groups:
relatively harmless - to the permissible concentration of up to 100 mg / m;
malovrednye - with a possible concentration to 10 mg / ml;
bad - with the allowable concentration of 1 mg/m3;
particularly damaging - to the permissible concentration below 1 mg / m
The first group includes primarily a pair of solvents for the second - some solvents, nitro compounds, carbon monoxide, furfural, ammonia, sulfur dioxide, methyl alcohol, etc., to a group of pests - sulfuric acid, phenol, chlorine, to a group of particularly harmful - mercury, lead and its compounds, phosphorus anhydride selenide, telluride and its oxides, compounds of uranium, hydrogen cyanide and other substances.
Speaking of gas, vapor and aerosols, we should mention about the dynamics of their spread around the room. If in the heat and vlagovydeleniyah local excess of permissible concentrations of heat and moisture safe for humans, then the evolution of gases, fumes and aerosols of local high concentrations can be dangerous and sometimes fatal.
Gases, fumes and aerosols are almost never distributed evenly around the room, both horizontally and vertically. On the one hand, well, since it allows to remove hazards from their areas of greatest concentration. On the other hand, this feature can be dangerous if the person would be in an area of high concentration of pollutant due to irresponsible allocation of jobs or improperly designed ventilation.
With gas, steam and dymopodobnyh hazard particularly important to correctly represent the conditions of their release. Very important to distinguish, whether hot or cold process, it does. M place jet or surface gas emission, whether directed currents of air created by the machinery or movement of material, and to know the exact location of the source of hazards in relation to the worker.
Noxious gases, fumes and aerosols may be released into the room in different ways, the main of them: chemical reactions in a leaky equipment, breaks through leakages of pipelines and vehicles, working under pressure, evaporation from open surfaces, direct entry to the premises.