BSI also holds the copyright, in the UK, of the publications of the international standardization bodies. In determining the leakage round an openable window the total length of cracks should be measured and multiplied by the appropriate factor for unit length from Table 5. For an intermittent opening such as a door, a lower air velocity than that suggested for the permanent opening can be used, and the value will depend on the position of the door. In the event of fire, airflows are set up in opposition to the smoke flow by opening vents on the fire floor. In a building, particularly a large building, there may be several pressurized spaces.
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For this reason it is recommended that the operation of any such system should 5588 be the sole method of initiating the emergency operation of a pressurization system.
Fan static pressure Fan total pressure minus velocity head at fan discharge. When toilet or other areas that are directly connected to a pressurized space have mechanical extract systems the leakage rate into them is either: Typical leakage areas for the four types of door likely to be found as the closure to a pressurized space are given in Table 3. Another possibility is a mixed system for the escape route, for instance a pressurized staircase with a naturally ventilated lobby between it and the accommodation.
We are a non-profit group that run this website to share documents. NOTE 2 The figures in column 3 vent size 0.
The emergency operation of any system should be tested weekly to ensure that each fan operates. The air intake and the discharge point should have at least 5 m horizontal separation.
BS 5588 Part 4 1978
Please download Chrome or Firefox or view our browser tips. The only satisfactory way of establishing that a pressurization installation is operating correctly and according to the design concept is to make physical measurements of the pressure differentials across closed doors and of the air velocities through open doors.
The use of a smoke detector in the air conditioning ductwork should not be relied on for this purpose because of the dilution of the smoke that will occur when several floors are served by the same system. However, either method will be acceptable subject to any special circumstances dealt with in this code. To calculate 3assume that the airflow into each lift shaft is still the value used in the design calculations.
Bs 4 fire precautions in the design, construction by Education Vietmastec - Issuu
The relative merits of a one-stage or two-stage system have been discussed in 4. To calculate 2use the method given in a above. Installations should comply with the recommendations given in BS No restrictions will arise when all the staircases in a building are pressurized, but the use of pressurized and naturally ventilated staircases in the same building will introduce difficulties and should be avoided if possible.
Open door is assumed to have an area of 1. If possible, the same levels should be used for lobbies and corridors but levels slightly lower may be used for these pqrt if desired.
BS Part 4 - Free Download PDF
It follows that any space to be pressurized has to be so constructed that any leakage of air through the building fabric will be minimal. The total airflow out of an open lobby door will be the sum of 1 the air supplied to the lobby by the supply duct, and 2 the airflow past a closed door from the staircase into the lobby.
CPDucts for building services5. The protection given by this method is entirely confined to the vertical part of the escape route. This is less than the 0. It is normally advisable for the engineer responsible for the system to be present at the test s. The purpose of other fire-protection measures installed in the building will almost certainly be the extinguishing of a fire should one occur; this is different from the purpose of pressurization, which will be to prevent the ingress of smoke into an escape route.
It is only appropriate in buildings where no smoke control is needed for the horizontal part of the escape route on each floor of the building and, in general, it should be used only when a staircase is approached directly from the accommodation area or through a simple lobby.
Two lift entrance doors in each lobby and double-leaf door between lobby and accommodation.
Chapter IV-1, which will appear as BS Designs have been suggested for a scheme in which pressure differentials are not developed inside the building but air is introduced in such a way that the whole building is raised to a pressure in excess of that obtaining outside the building.
The recommended methods are set out in 6.
During a fire emergency all protected staircases interconnected by lobbies, corridors or accommodation areas should be simultaneously pressurized. The need for fire dampers can be avoided if the duct is situated wholly within a protected enclosure. 44
To obtain these velocities through large openings will require large volumes of air and this system of smoke control may well be uneconomic except for very special circumstances.