Smoke and gas tightness of Hilti Firestop products

Transcription

1 Smoke and gas tightness Smoke and gas tightness of Hilti Firestop products The enclosed pages are taken from the Brochure Smoke and gas tightness Edition 2006 Please note the tables in this extract may be out of date For Material Safety data sheets visit the technical library at Hilti (Gt Britain) Ltd TECHNICAL ADVISORY SERVICE TELEPHONE Quality Management System Certification Standard: ISO 9001:2008 Issued by: The Swiss Association for Quality and Management Systems SQS. Registration No: (The current certificate can be downloaded from Field of activity: Market Organisation. Note: The certificate of Hilti (Gt. Britain) Ltd. is a sub-certificate to the master certificate of Hilti Aktiengesellschaft,FL-9494 Schaan with the field of activity: Research, Development, Manufacturing, Sales and Service. Hilti (Gt. Britain) Limited, 1 Trafford Wharf Road, Trafford Park, Manchester M17 1BY Telephone:

2 Smoke and gas tightness 30 YEARS Contents Hilti Fire Prevention Smoke and gas tightness pages YEARS Standard details showing the assembly required to obtain the required acoustic performance can be found in the product details in the Hilti Firestop specifiers binder or can be downloaded from the technical library. CAD files of the standard details FS ***-** can be downloaded from the technical library at Revision History June 2011 May 2013 First release Update Hilti (Gt. Britain) Limited, 1 Trafford Wharf Road, Trafford Park, Manchester M17 1BY Telephone:

3 Contents 1. Introduction 3 2. Important terms 4 3. Smoke- and gas-tightness in the event of fire 6 4. Sealing compartments equipped with gas extinguishing systems 7 5. Air-tightness of buildings Approved Document L in GB 8 6. Protection from odours and hazardous gases gas diffusion 9 7. Measuring gas-tightness Tested systems from Hilti 11

4 1. Introduction The smoke- and gas-tightness of firestop products is of decisive importance in the event of fire as it may save lives. Moreover, gas-tightness also plays an important role in the thermal insulation of buildings. The requirements to be complied with in terms of smoke- and gas-tightness are laid down in various laws and regulations. Hilti firestop products are not only tested and approved internationally in accordance with the stipulations of passive fire prevention regulations, they are also comprehensively tested to ensure compliance with the standards currently applicable to smokeand gas-tightness. These pages describe the general principles of smoke- and gas-tightness and show how these are applied in practice on the basis of practical examples. page 3

5 2. Important terms Gas permeability For gas permeation to take place, a difference in pressure (P) must exist on each side of the wall or the material being tested. Gas permeability If a construction product or sealing material contains microfissures, large quantities of gas may be forced through it. The pressure difference and the size of the gas molecules are therefore decisive factors. C C2 Gas diffusion Gas diffusion In the case of gas diffusion, the pressure (P) on each side of the wall is the same but the concentration (C) of a gas is significantly higher on one side than on the other. An example of this is the presence of a strong odour in one of two adjoining rooms. Due to the lack of a difference in pressure, the speed of diffusion of the gas molecules is considerably lower than in the case of gas flow due to permeation. For diffusion to take place, however, the molecules do not rely on the presence of microfissures, but pass directly through the material concerned. The speed of diffusion is therefore influenced, above all, by chemical / physical interactions between the gas molecules and the material of the wall. Gas-tightness Gas-tightness is the term applied to a construction material s ability to provide a gastight seal. This value is measured in volume per unit of time and surface area (e.g. m 3 / h m 2 ). Regulations Approved Document L Great Britain Approved Document L specifies the energy conservation measures to be incorporated in buildings. Airtight sealing of the shell of the building is one of its stipulations. Moreover, it demands that products providing good thermal insulation are used. EnEV Germany The Energy Conservation Act applicable in Germany is also a law intended to reduce the energy loss in buildings. In contrast to Approved Document L, it specifies no values for the gas-tightness of the shell of the building. page 4

6 Applications The subject of smoke- and gas-tightness is of decisive importance in the following applications. Heating oil Gas extinguishing systems Smoke and fumes Odour from facilities Smoke- and gas-tightness in the event of fire The most important point is imperviousness to smoke and fumes. It is the smoke and fumes from fires that cause most deaths and the greatest damage. Accordingly, these must be effectively prevented from spreading in the event of fire. Gas extinguishing systems also have an influence on firestop products. Firstly, these systems cause a significant rise in pressure in the room concerned. Secondly, the extinguishing gas may be harmful to the persons present in the building. Gas- and air-tightness of buildings Within the scope of regulations to promote energy conservation, laws in various countries specify that joints and penetrations in buildings must be air- and gas-tight. Protection from critical gases and odours In many branches of industry, the spread of odours or critical gases must be prevented through use of impermeable materials. page 5

7 3. Smoke- and gas-tightness in the event of fire Smoke- and gas-tightness in the event of fire is an important criterion in all common tests of passive fire prevention measures. Smoke and fumes present the greatest hazard to persons in burning buildings: Smoke escaping at an inadequately sealed plastic pipe in a fire test after only 8 minutes Smoke spreads at the rate of meters per minute in a building. Smoke greatly reduces visibility in a building or part of a building: Half of the survivors of a fire are able to see no further than 3.5 meters. Two thirds of the fatalities in fires are due to the direct or indirect effects of smoke and fumes. More than half of all fire victims were not in the room in which the fire broke out. Smoke and fumes present a risk not only to human life, but also to property. As a result of the materials from which items in the building are made, including cables and pipes, the smoke and fumes generated usually also contain halogens (chlorine, bromine). Where moisture is present, these halogens can transform into acids capable of attacking metals or paper. Computer facilities and libraries are at particularly high risk as they can be completely destroyed by smoke and fumes. page 6

8 4. Sealing compartments equipped with gas extinguishing systems A gas extinguishing system is a firefighting system that extinguishes a fire by reducing the oxygen content of the atmosphere in the room to less than 15%. The gas used to extinguish the fire may be carbon dioxide, an inert gas or a gas mixture. Gas extinguishing systems are installed, above all, in areas where it can be presumed that the use of water or foam to extinguish a fire could result in serious, possibly irreparable damage, e.g. in archives, libraries or computer facilities. With most gas extinguishing systems, persons must be evacuated from the area affected before the extinguishing gas is allowed to flow into the room in order to ensure that occupants suffer no physical harm as a result of the reduced oxygen content. Carbon dioxide extinguishing systems are particularly critical in this respect as the sudden drop in temperature and quick reduction of the atmosphere s oxygen content makes escape from the extinguishing area almost impossible. A gas extinguishing system Thanks to their tested gas-tightness, Hilti firestop products help to seal of the rooms concerned, thereby safeguarding the unaffected areas. The occupants of adjoining rooms can thus be actively protected. Planners and tradesmen must therefore consider the following questions concerning the sealing of rooms equipped with gas extinguishers: How well sealed are any penetrations through walls and floors etc.? Can the extinguishing gas and the resulting smoke and fumes be contained effectively within the fire compartment? Are the seals capable of withstanding the pressure of the gas released into the compartment? The values given by Hilti for the gas-tightness of Hilti firestop products have been determined at pressures of 50 Pa and 200 Pa. In addition, selected Hilti firestop products have been put through an explosion test in which a seal is subjected to a very sudden rise in pressure of 0.5 to 2 bar. This pressure corresponds to 50, ,000 Pa. The tested Hilti products withstand this stress and are grouped, according to result, in the classes EPR 1 to EPR 4 in accordance with EN and EN The results achieved confirm that the tested firestop systems possess not only the necessary gas-tightness, but also the strength and resistance required to prevent extinguishing gas, smoke and fumes escaping and spreading into other fire compartments. page 7

9 5. Air-tightness of buildings Approved Document L in GB Energy conservation laws take the gas permeability of the building components used as a measure of the gas- or air-tightness of the building itself. In accordance with the latest energy conservation regulations as per Approved Document L, air leakage in new buildings must not exceed a value of 10 m 3 / h outer surface area in m2. Nevertheless, the aim is to achieve a value of between 2 and 3 m 3 / h m 2. Building type Maximum air leakage in m 3 / h m 2 at 50 Pa Current value Target Office buildings Natural ventilation 10 0 Air conditioning / low-energy building 5 3 Factories, warehouse buildings 10 0 Shopping centers 5 3 Museums and archives Refrigeration and freezing rooms Residential buildings 10 5 Blower door test Air- and gas-tightness is tested by way of the so-called blower door test, during which the pressure of the atmosphere in the building is increased. The main weak points in buildings are: Structural joints Door and window joints Roof connections, especially with trapezoidal sheet metal roofs Penetrations for pipes and cables through outside walls or walls between sections of the building Door and window joints There is now increasing awareness that uncompromising adherence to the regulations and their implementation leads to a considerable reduction in energy costs (heating, cooling) without any significant rise in building costs. This, however, requires that such aspects of the construction work are taken into account at the planning stage. The search for sources of leakage after completion of construction is an extremely time-consuming and costly process, as each section of the building has to be thoroughly examined and tested. We recommend several of our firestop products for subsequent or supplementary sealing and refurbishment work on the shells of buildings. These products are easy to use and their ability to achieve an airtight seal has been verified in tests. The table below shows the products we recommend and their possible applications: Surface Joints Outside Penetrations sealing walls and openings CP 601S X X CP 606 X X CP 611A X CP 620 X CP 670 X X CP 672 X X CP 673 X X Mineral wool must be used for backfilling with all products except CP 620. page 8

10 6. Protection from odours and hazardous gases gas diffusion One further aspect of gas-tightness is protection from odours and hazardous gases, for example: Swimming pools chlorine Petrochemicals petrol / gasoline and oil vapours Filling stations fuel vapours Sewage treatment plants sewage gas In situations where firestop products are constantly exposed to hazardous gases, two points must be taken into account: chemical resistance and gas-tightness. Chemical resistance The chemical resistance of Hilti firestop systems has been tested in accordance with DIN EN The test was carried out, on the one hand, in the liquid phase, i.e. the firestop products were submerged in the chemical substance. In addition, the specimens were also tested in the gas phase, i.e. the specimens were stored for a period of time above the surface of the liquid substance. The results of the tests for each firestop product are available on request. Gas-tightness gas diffusion Sealing off to protect against odours or gases for a short period of time presents no great difficulties as, in this case, the laws of gas permeability apply. This means that gases and odours can find their way into the room to be protected only through microfissures in the seal or building materials. Sealing to protect a room over a long period of time, however, presents a far greater challenge. In this case, the laws of gas diffusion play the decisive role: gases permeate through the material in a gradual process due to differences in concentration. Processes of this kind depend on various factors such as gas concentration, temperature and the material involved. In order to achieve a seal that remains effective over a long period of time, comprehensive and time-consuming tests have to be carried out with exactly the same configuration to be used in practice (firestop system and the corresponding gas). In the case of gas diffusion, each instance always has to be viewed as an individual case because in addition to the applicable gases, the surrounding influences also have to be taken into account. There is no generally applicable test procedure that provides values suitable for comparison. If rooms are to be constantly exposed to gases, as in the situations listed above, it is essential that the chemical resistance of the firestop products to these gases is clarified in advance. Sealing an opening with a Hilti firestop product nevertheless always achieves a reduction of the gas concentration, i.e. a reduction of vapours and odours. page 9

11 7. Measuring gas-tightness The tests carried out to measure gas-tightness were conducted in cooperation with the IBeWa Institute and the Technical University Bergakademie, Freiberg, Germany. Preparation of specimens for measurement of gas-tightness All specimens were fitted into acrylic glass or steel testing devices in accordance with the current fire prevention approvals as per DIN 4102, BS 476 and ASTM E 814. Preparation of specimens Reference gases Methane, nitrogen, and carbon dioxide were used as the reference gases for testing gas-tightness. All three gases are composed of small molecules. Methane is the main constituent of natural gas and is flammable Nitrogen and carbon dioxide are used in extinguishing systems Nitrogen is the main constituent of the air Conducting the tests The procedure for determination of the actual gas flow was based to a some extent on DIN EN The cylinders containing the fully-cured specimens were fitted into the measuring apparatus. The gas to be used for the test was then allowed to flow into the chamber on one side of the specimen up to the desired pressure. The test measurement was taken and recorded once a steady volumetric flow rate through the test specimen was established. To be on the safe side, specimens through which no flow of gas could be detected (gas-tight) were subjected to a further time of at least one hour at a pressure of 1550 Pa. Measuring apparatus The volumetric flow rates measured for each gas were then converted into the following unit: m 3 per hour per m 2 of surface area (m 3 / h m 2 ). page 10

12 8. Tested systems from Hilti The following Hilti firestop systems were tested in a procedure following the example of EN Firestop system Pressure difference 50 Pa Pressure difference 200 Pa CP 601S CP 604 CP 606 CP 611A CP 612 / FS One CP 620 CP 636 CP 657 / 658 CP 670 CP 671 CP 672 CP 673 This brochure was produced by Hilti Corporation, BU Chemicals, Schaan, Liechtenstein, in cooperation with Hilti Entwicklungsgesellschaft mbh page 11