Good day to all regular readers of our site and colleagues in the workshop. The topic of the article today is “the height of the compensatory inflow in smoke removal systems.” This refers to the installation height of the air duct grille of the supply system, that is, from where the air will blow. We receive quite a lot of questions on this topic, and the main question is: at what height? How many in meters and centimeters? They write about comments from fire inspectors and examinations in this regard. Today, we will try to figure this issue out together.
To begin with, to make it clear, I will give you a fragment of a real letter from one of our Readers:
“Good evening, I have a question regarding the boundaries of the lower part (zone) for compensation of smoke removal systems from the corridors. In the standards of the Russian Federation, this limit is only defined in SP 154. And it should not exceed 1.2 m. Should it be accepted for other premises for other purposes? ……….. If the boundary is not indicated, is it possible to focus on the upper boundary of the doorway of a given room?”
Now let’s take a look at what our standards say on this issue. First, we present the fragments of requirements that interest us in this context from clause 8.8, SP7.13130-2013. (the document can be found and downloaded in our regulatory library) and highlight the main points:
"8.8. To compensate for the volumes of combustion products removed from premises protected by exhaust smoke ventilation, supply smoke ventilation systems must be provided with natural or mechanical motivation.
For natural air flow into the protected premises, openings can be made in external fences or shafts with valves equipped with automatically and remotely controlled drives. Openings must be at the bottom of the protected premises. Valve ledges must be equipped with means to prevent freezing during the cold season. To compensate for the flow of outside air into the lower part of atriums or passages, external doorways can be used emergency exits . Doors of such exits must be equipped with automatically and remotely controlled forced opening drives. ………….."
That is, it is clear - the height of the compensatory inflow for high rooms of atriums and passages, compensation is possible at the height of the openings entrance doors, and these doors can be up to 3-4 meters high - I myself have seen such high doors, for example, in a church. In other rooms, the height of the compensatory inflow is carried out to the lower part of the room. That is, logically we divide the height of the room in half and the height from the floor to the resulting dividend will be called the lower part of the room. Accordingly, the height from the middle of the height of the room to the ceiling will be the upper part of the protected room. For example, with a room height of 4 meters, the distance from the floor to 2 meters is the lower part of the protected room, and the distance from 2 meters to the ceiling (4 meters) is the upper part of the protected room. So in this very lower part, from the floor to 2 meters, the height of the compensatory inflow is located. This is the first condition! So far everything is logical and understandable, isn’t it?
Now one more thing. For the correct operation of the inflow system, together with the smoke control exhaust ventilation system, the height of the compensating inflow must be correctly located relative to the height of the smoke exhaust valve, i.e. suction device. To ensure air-smoke convection, the smoke removal device (valve) must be located HIGHER than the height of the compensatory inflow - the air grille. This is the second condition! Everything is also logical and understandable, isn’t it? Hence, the question immediately arises - at what height are smoke intake devices (smoke exhaust valves) installed, in accordance with existing standards? Open SP7.13130-2013, look at clause 7.8:
"7.8. When removing combustion products from corridors, smoke intake devices should be placed in shafts under the ceiling of the corridor, but not below the upper level of the doorways of emergency exits…….”
That is, everything is clear - from the upper level of the doorway (on average 2 meters) to the ceiling - somewhere within these limits.
We give examples of the main installation errors, so that it is completely clear.
If you do not take into account the first condition and perform compensation only according to the second condition, we will consider the result. For example, the height of the compensatory inflow is located at a height of 2 meters, when installing a smoke intake device at a height of 2.2 meters, with a total ceiling height of 3 meters. It seems that the second condition is fully satisfied. However, you will receive a notice from the fire inspector in the following plan. He will simply divide 3 meters of the total height of the room by 2 and get half the height of the room - 1.5 meters and say something like the following text - “from the floor to 1.5 meters - this is the lower part of the room, and your height of the compensatory inflow is set at a height of 2 meters, which does not comply with the provisions of clause 8.8 of SP7.13130-2013” - and he will be absolutely right.
If on the contrary, you fulfill the first condition. In a corridor 8 meters high (this also happens), the height of the compensatory inflow you set will be 3.9 meters, that is, to the lower part of the protected room. At the same time, the smoke intake device (smoke exhaust valve) is installed at a height of 2.2 meters (above the door opening 2 meters high). Everything seems to be in accordance with the first condition. However, the smoke removal system will not work correctly - the exhaust will be lower than the inlet and you will receive a corresponding notice.
Based on the above, we can draw the following conclusion - compensation inflow height is determined subject to the mandatory fulfillment of the above two conditions.
Now let’s return again to the second part of our Reader’s question above. Let's see how the height of the compensatory inflow is determined in SP154.13130-2013, clause 6.3.2 (the document can be found and downloaded in our regulatory library):
« 6.3.2 To compensate for the volumes of combustion products removed into the lower
parts of the protected premises must be provided with a dispersed supply of outside air: with a flow rate ensuring an imbalance of no more than 30%, at a level not higher than 1.2 m from the floor level of the protected room and with an exhaust velocity of no more than 1.0 m/s.”
Well, the next point will also be interesting for analysis:
6.3.3 All supply and exhaust smoke ventilation systems should be provided with mechanical draft stimulation.
Well, in general, everything is clear - maximum height compensatory inflow is determined exactly - 1.2 meters. However, pay attention to the title SP 154.13130-2013 “Built-in underground parking lots. Requirements fire safety" That is, these requirements apply to a specific type of facility, and not to all premises in which smoke removal systems are installed. Moreover, pay attention to the requirement for the organization to exclusively mechanical systems according to clause 6.3.3. Again, this requirement only applies to built-in underground parking spaces. On other objects you can do supply and exhaust systems WITHOUT MECHANICAL INCIDENCE! And this is wonderful, since, frankly speaking, I am not a fan of mechanical compensating systems, which I have repeatedly written about on the pages of our website. You can read an article on this topic by following the link.
Also, it must be said that there may be other types of objects that may have SPECIAL requirements in terms of equipping them with smoke removal systems and inflow compensation, similar to built-in underground parking lots, as discussed above in the text. Therefore, when solving such problems, first of all, start by determining the type and purpose of the premises - determine whether there are SPECIAL requirements for this type of premises. If there are such requirements, then act in accordance with these instructions. If special requirements no, then act in accordance with general requirements SP7.13130-2013.
This concludes the article “height of compensatory inflow in smoke removal systems”, I hope that the recommendations and information presented by me are useful.
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When is it necessary to install smoke exhaust?
Experts have reliably established that in a fire, most people die from poisoning carbon monoxide and other combustion products. Smoke spreads much faster than fire and can lead to loss of consciousness and cardiac arrest much earlier than a person can get out of the room. In addition, smoke reduces the ability to navigate in space, forcing the victim to move by touch and often move away from escape routes.
Taking into account all these factors, forced or static smoke removal systems are installed in places of greatest danger. Such places include:
- long corridors, which are located on the second floor and above and have a length of over 15 meters,
- halls of buildings,
- dressing rooms,
- as well as high-rise residential buildings.
In addition, smoke removal must be installed in large-area stores, basements, tunnels, mines and other dangerous places, in accordance with SP 7.13130.2009 and Federal Law-123. Based on the same legislative acts, combustion products, temperature and smoke toxicity are calculated. Calculation data corresponds to throughput smoke removal systems. It is worth noting that in those rooms where a gas, powder or aerosol fire extinguishing, these requirements do not apply.
A static smoke removal system is an ordinary valve that blocks the ventilation system and prevents the spread of smoke. Compulsory system includes a whole complex equipped with powerful fans that provide exhaust in the event of a fire. Naturally, most systems are activated automatically, using special sensors that respond to an increase in temperature or the presence of smoke. Forced activation of the smoke exhaust system is also possible.
Special requirements when designing a smoke removal system are put forward for high-rise buildings and educational institutions. If the height of the building is more than 28 meters (this is the length of the fire escape), the smoke removal system is not only mandatory, but should also be aimed at creating overpressure on the upper floors and in the elevator shaft, thereby preventing the spread of smoke. In multi-storey educational institutions There must be smoke-free flights of stairs. It is worth noting that in some places local regulations allow you to deviate from the main legislation, for example, if the premises have rooms with good protection from smoke and individual ventilation.
In general, the work of any system should be aimed at ensuring that in the event of a fire people have time to evacuate. At the same time, the system itself must also meet certain requirements, for example, a fan must withstand long work at high temperatures ah and have the necessary power to work as an extractor or blower. The same applies to ventilation ducts, which must be made of non-flammable metal and be heat-resistant.
We have been working in the field of design and installation of smoke removal systems for several years; if you have any questions, you can contact us by phone.
Question :
Section 7 and clause 8.5 of SP 7.13130.2013 includes the concept of corridor length. How to calculate the length of a complex corridor geometric shape and determine the number of windows 1.6 m long for natural ventilation in accordance with clause 8.5, so as not to provide a mechanical smoke removal system? Is a light pocket several meters long included in the "length of the corridor"?
Answer :
In accordance with subclause “c” of clause 7.2 of SP 7.13130.2013 “Heating, ventilation and air conditioning.
Fire safety requirements" removal of combustion products in case of fire by exhaust smoke ventilation systems should be provided from corridors without natural ventilation in case of a fire longer than 15 m in buildings with two or more floors :
Production and warehouse categories A, B, C;
Public and administrative;
Multifunctional.
In accordance with clause 8.5 of SP 7.13130.2013, for natural ventilation of corridors in case of fire, openable window or other openings should be provided in external fences with the top edge located at least 2.5 m from the floor level and a width of at least 1.6 m for every 30 m length of the corridor.
The required dimensions and number of openable window and other openings for natural ventilation of rooms or corridors in case of fire can be determined by calculation in accordance with the requirements of clause 7.4 of SP 7.13130.2013.
In accordance with subparagraph "a" of clause 7.4 of SP 7.13130.2013, the consumption of combustion products removed by exhaust smoke ventilation should be calculated depending on the heat release power of the fire, heat loss through the enclosing building structures of the premises and ventilation ducts, temperature of combustion products removed, outside air parameters, state (positions) of door and window openings, geometric dimensions for each corridor no more than 60 m long - in accordance with subparagraphs "a" - "d" of paragraph 7.2.
In accordance with clause 4.3.3 SP 1.13130.2009 "Systems fire protection. Evacuation routes and exits" (as amended on December 09, 2010), corridors longer than 60 m should be divided by type 2 fire partitions into sections, the length of which is determined according to (SP 7.13130), but should not exceed 60 m.
At the moment, the definition of “Light pocket” has been established - a room with natural light, adjacent to the corridor and serving to illuminate it (clause 3.7 of Appendix “B” of SNiP 31-01-2003 “Residential multi-apartment buildings”).
Premises - part of the volume of a building or structure that has a specific purpose and is limited building structures(Article 2 - Federal Law of December 30, 2009. N 384-FZ " Technical regulations on the safety of buildings and structures" (as amended on July 2, 2013)).
At the same time, in accordance with clause 5.2.7 SP 2.13130.2012 "Protection systems and fire protection. Ensuring the fire resistance of protected objects" (as amended on October 23, 2013) evacuation routes ( common corridors, halls, foyers, vestibules, galleries) should be distinguished by walls or partitions provided from the floor to the ceiling (covering).
These walls and partitions must be adjacent to blind areas of external walls and not have open openings that are not filled with doors, hatches, translucent structures, etc. (including above suspended ceilings and under raised floors).
Accordingly, on the one hand, it is possible to conclude that a light pocket (a room with natural light, adjacent to the corridor and used to illuminate it) is an independent room and does not belong to the corridor, and on the other hand, this room (light pocket ) is not separated from the corridor by walls or partitions, the light pocket must be considered part of the corridor.
Accordingly, it is possible to conclude that for natural ventilation of corridors in case of fire, openable window or other openings should be provided in external fences with the top edge located at least 2.5 m from the floor level and a width of at least 1.6 m for every 30 m length of the corridor (light pockets must be included in the total length of the corridor).
In this case, the length of the corridor (corridor section) should not exceed 60 m.
Corridors divided into sections by fire partitions with doors are considered as separate sections for calculating the combustion products removed.
Accordingly, to determine the required dimensions and number of window openings to be opened for natural ventilation of corridors in case of fire, it is necessary to carry out a calculation in accordance with the requirements of paragraph 7.4 of SP 7.13130.2013.
If during the calculation it is established that the existing window openings provide natural ventilation of the corridors in case of fire, then in this case It is possible not to provide for the installation of an exhaust smoke ventilation system in the corridors.
Smoke protection of buildings includes a set of technical solutions that ensure smoke-free evacuation routes, individual premises and buildings as a whole.
Types of technical solutions are regulated by relevant regulatory documents depending on the purpose of the buildings, the conditions of fire development, the potential danger of smoke spreading beyond the burning premises, technical and economic indicators and are divided into volumetric - planning, structural and special.
Volume-planning solutions include solutions that include: dividing the volume of a building into fire-resistant compartments and sections, isolating escape routes from adjacent rooms, isolating rooms with fire-hazardous technological processes and placing them in the plan and on the floors of the building.
Structural solutions include the use of smoke-tight enclosing structures with a sufficient fire resistance limit and appropriate protection of door and technological openings, openings for laying communications, as well as the use of special designs of structural elements for removing smoke in the desired direction: smoke and ventilation shafts, hatches, openings.
Special technical solutions for smoke protection of buildings include the creation of smoke removal systems with mechanical or natural impulse, as well as systems that provide excess air pressure in the protected volumes: staircases, elevator shafts, vestibules - airlocks, etc.
Smoke protection of buildings is carried out by a combination of technical solutions. Yes, smoke-free stairwells in high-rise buildings can be achieved by installing floor-by-floor entrances to the staircase through air zone on balconies, loggias or galleries, or by creating excess air pressure in the volume of the staircase using mechanical ventilation systems. If there is an air pressurization system to create a pressure difference in the doorways of the staircase on the floors of the building, it is necessary to install a smoke removal system from the floor corridors. In addition, in both options to ensure smoke-free staircases, it is necessary to provide measures to isolate the protected volumes from basements and attics, rooms for various purposes on the floors of the building.
The main purpose of smoke protection for a building is to create conditions for the evacuation of people in case of fire. Particular importance is attached to this direction in the design, construction and operation of buildings with large numbers of people, child care institutions, hospitals, etc.
If the issues of smoke protection of a building are unsatisfactorily resolved, combustion products spread through elevator shafts, corridors, staircases, ventilation systems, garbage chutes, holes and openings in the enclosing structures, which complicates the evacuation of people, and in some cases, blocks it. For example, filling floor corridors with smoke eliminates the possibility of using even smoke-free staircases for evacuation.
Smoke has toxicological and psychological effects on humans. In rooms filled with combustion products, visibility is sharply reduced, it is difficult for people to orient themselves during evacuation, and difficulties are created in detecting the source of the fire and extinguishing it. The situation during a fire is even more complicated when the combustion of substances releases products of incomplete combustion or toxic substances. In addition, combustion products heated to high temperatures contribute to the spread of fire and, under certain conditions, can cause repeated fires at a considerable distance from the original one. This predetermines the second direction of smoke protection, the development of a fire and the creation of conditions for its successful extinguishing. buildings associated with restrictions
Thus, technical solutions for smoke protection of buildings must guarantee protection from smoke of evacuation routes for a time sufficient to evacuate people, create conditions for successful localization and extinguishing of a fire.
In accordance with clause 8.2 of SNiP 41-01-2003, smoke control exhaust ventilation systems for removing combustion products in case of fire should be provided with:
a) from corridors and halls of residential, public, administrative and multifunctional buildings with a height of more than 28 m. The height of the building (for evacuation of people) is determined by the difference between the elevations of the passage surface for fire trucks and the lower elevation of the opening window (opening) in the outer wall top floor(not counting the upper technical);
b) from corridors (tunnels) of basement and ground floors without natural lighting by their light openings in external fences (hereinafter - without natural lighting) of residential, public, administrative, industrial and multifunctional buildings at exits to these corridors from premises intended for permanent presence of people (regardless of the number of people in these premises);
c) from corridors longer than 15 m without natural light for industrial and warehouse buildings of categories A, B, B1-B2 with two or more floors, as well as for industrial buildings of category B3, public and multifunctional buildings with six or more floors;
d) from common corridors and halls of buildings for various purposes with smoke-free stairwells;
e) from corridors without natural light in residential buildings, in which the distance from the door of the most remote apartment to the exit directly to the staircase or to the exit to the vestibule leading to the air zone of a smoke-free staircase type H1 is more than 12 m;
f) from the atriums of buildings with a height of more than 28 m, as well as from atriums with a height of more than 15 m and passages with doorways or balconies overlooking the space of atriums and passages;
g) from stairwells of type L2 with lanterns of hospital buildings of medical institutions that open automatically in case of fire;
h) from each production or warehouse premises with permanent workplaces without natural light or with natural light through windows and lanterns that do not have mechanized drives for opening transoms in the windows (at a level of 2.2 m and above from the floor to the bottom of the transoms) and openings in lanterns (in both cases with an area sufficient to remove smoke in case of fire), if the premises are classified as categories A, B, B1-VZ, as well as B4, D or D in buildings of IV fire resistance degree;
i) from each room without natural light:
Public, intended for mass gatherings of people;
An area of 50 m2 or more with permanent workplaces, intended for the storage or use of flammable substances and materials;
Trading areas;
Wardrobes with an area of 200 m2 or more. It is allowed to design the removal of combustion products through an adjacent corridor from premises with an area of up to 200 m2: production categories B1-B3 or intended for the storage or use of flammable substances and materials.
The requirements of clause 8.2 of SNiP 41-01-2003 do not apply to:
a) for premises (except for premises of categories A and B) with an area of up to 200 m2, equipped with automatic water or foam fire extinguishing installations;
b) on premises equipped with automatic gas or powder fire extinguishing installations;
c) to the corridor and hall, if direct removal of combustion products is planned from all rooms with doors to this corridor or hall.
Note - If in the area of the main room for which removal of combustion products is provided, there are other rooms, each with an area of up to 50 m2, then removal of combustion products from these rooms may not be provided.
