Selections vapors of volatile liquids
We note one fact concerning the allocation of vapors of volatile liquids - such as ether, alcohols, benzene and gasoline. These liquid evaporates rapidly at room temperature, consuming requirements for the evaporation of heat from ambient air and cool it. If the premises are no significant sources of heat, then the highest concentration of harmful substances will be in the lower zone, which implies removing the air.
As a rule, should not be concentrated flow in rooms with toxic hazards, regardless of the hood. Concentrated flows may be justified only as a local, such as air showers, or other aimed at the working of the jets. Of toxic hazards in all cases, we recommend feeding the supply air to the zone of least contamination and at least partially - in the work zone. Serve the air in the breathing zone in most cases it should be (except for air showers) are dispersed through diffusers with uniform distribution, the velocity of the air outlet to choose the minimum to avoid feeling the blast.
In special cases - for large cubic space (about 30-40 thousand m3), a small number of employees and the localization of harmful gases local suction - is admissible blow is concentrated in relatively clean areas. This applies to shops with the joint release of heat and gases at malovrednyh allowable concentration of 10 mg / mg.
With automated processes and a few jobs at the controls, but total inflows (sometimes at the expense of aeration), preferably local unit "air oasis" at the controls.
Note the specificity of compensation of the local hoods influx in rooms with variable exhaust, the volume of which can vary from zero to maximum. In this room lodge inflow force is not recommended, because a decrease in the volume of exhaust air from the possible overflowing of "dirty" space in a nearby "clean". In this case we recommend feeding the supply air to the corridor, where it will be sucked into the ventilated room by the vacuum. It is rational to use self-closing of the lattice. They need to be installed in sufficient numbers to create minimal resistance to the passage of air.
Premises in which release hazardous gases and vapors, in some cases, explosive. This fact must be considered when designing the ventilation system.