Basic concepts and definitions

Fire prevention (FP) is provided by a variety of ways and means: technological, construction, organizational and technical. FP is the most important part of the overall problem of providing fire and explosion hazards of different objects, so it is given the highest priority in dealing with the protection of objects from fires and explosions. FP can be represented in the form of two systems: a system of fire prevention and fire protection. Assessment of characteristics of fire and Explosion hazardof industries discussed in the previous laboratory work, can also be attributed to the FP.

Fire prevention in the design and construction of an industrial enterprise includes the following issues:

– Improving the fire resistance of buildings and structures;

– Zoning;

– Use of fire-breaks;

– Use of fire barriers;

– Ensuring the safe evacuation of people in case of fire;

– Ensuring the removal from the premises in case of fire gases and smoke.

Fire resistance of structures characterized by a limit of fire resistance, that  is the time in hours from the start of the test the design on a standard temperature mode until one of the following: occurrence the cracks or holes in the construction, through which the flame or combustion products penetrate; temperature rise of the unexposed surface of the structure by an average of more than 140 ° C; loss of its design load-carrying capacity; the transition of combustion into the adjacent structure or premises; structural failure of attachment points.

Depending on the size of the fire resistance of the main building structures and limits the spread of fire to these buildings and structures for fire resistance is divided into five classes (I, II, III, IV, V) with decreasing requirements.

Increase the fire resistance of buildings and structures can be lined or plastering of metal structures (for example, gypsum boards); plastering wooden structures lime-cement, asbestos-cement or stucco; fire retardant impregnation of wood flame retardants – chemicals (ammonium phosphate), giving it a non-combustibility; painting constructions with fire retardant paint.

Zoning is the grouping with the general layout of enterprises in certain complexes of objects related by functional purpose and basis of fire hazard. These constructions with high fire danger are located on the leeward side. This is also the correct device in-plant gate, which should ensure unimpeded passage of fire trucks handy to any building, as well as the selection of fire stations locations. One of the sides of industrial enterprise territory should be adjacent to a public road or to communicate with it by passages.

Fire breaks provide the prevention of the fire spreading from one building to another. In determining the size of fire breaks take into account the degree of fire resistance of buildings. Adjustable by rules magnitude of fire breaks between production and auxiliary buildings and closed warehouses are shown in Table. 10.1.

Table 10.1

The values of fire breaks between production and ancillary buildings

Under certain circumstances, exclude the possibility of the emergence or spread of fire, fire breaks are not standardized.

Fire barriers are walls, partitions, ceilings, doors, gates, hatches, tambour gateways and windows. Fire walls must be made of fireproof materials, have a fire resistance of at least 2.5 hours and build on the foundations. Fire walls are counting on sustainability, taking into account possibility of unilateral collapse of floors and other structures in case of fire.

Fire doors, windows and gates in the fire walls should have a fire resistance of at least 1.2 hours, and the fire overlap – at least 1 hour, such overlap should not have openings and holes through which can penetrate the products of combustion in case of fire.

In the design of buildings must be provided safe evacuation of people in case of fire. In the event of fire, people should leave any building within the normalized minimum time, which is determined by the shortest distance on the location of the exit from the building to the outside.

Number of emergency exits of an industrial building or structure shall be, as a rule, not less than two. Emergency exits should be placed dispersed. The minimum distance l between the most remote emergency exits from the premises (m) should be determined by the formula:

                                 l < 1,5 Р,                                    (10.1)

where P – perimeter of the room, m.

All escape routes (walkways, corridors, stairs, etc.) should be, as far as possible, smooth vertical walling without protrusions, all kinds of escape routes must have a normal and emergency lighting. The minimum width of the corridor or passage is determined by calculation, but should be at least 1.0 m.

The distance from the most remote workplace location to the nearest emergency exit and the distance down the corridor from the door of most remote areas should not exceed standardized values.

The minimum width of staircases is determined by calculation, but should not be less than the established under the terms of a single movement of people (2.4 m).

The width of the emergency exit of the industrial building is taken depending on the total number of people evacuating through this output, according to the norms given in the Table. 10.2. It should in any case not less than 0.8 m.

Table 10.2