Necessity of Carrying out Hot Smoke Tests in Atrium with Examples

Topic: Necessity of Carrying Out Hot Smoke Tests in Atrium with Examples

1. Introduction[pic 2]

Atrium is an old architectural feature with a history of over two thousand years and commonly adopted in modern architectural buildings (1)which is a large open area with several stories high, usually suited with glazed roof and large windows and often located at the main entrance of office buildings, shopping arcades or assembly halls etc.

Atrium design becomes more popular among various commercial buildings and shopping complexes as it gives occupants senses of large space and light.

However, differ from traditional building design; atrium with high room head imposes unclearness of functionality of typical fire safety provisions such as sprinkler heads, smoke detectors or fire detectors.

Moreover, current fire services guides regarding atriums in Hong Kong are incomprehensive and not well developed without extensive research reports.

In order to enhance fire safety in atrium, smoke extraction system, either dynamic type or static type is required as fire safety measure by the FSD of Hong Kong. Nonetheless due to large in volume of atrium, smoke extraction system usually does not comply with the prescriptive code which fail to provide an adequate smoke extraction rate of approximately 10 air change rate per hour for dynamic smoke extraction system or “free area” not less than 2% of floor area for static smoke extraction system.

As a result, HOT SMOKE TEST (HST) is required to be carried out on site for evaluating the performance of smoke extraction system.

1. Codes / Guidelines Regarding Hot Smoke Test[pic 3]

The following local codes and international guidance specify details of Hot Smoke Test:

• FSI Code 2005 by Fire Services Department (FSD), Section 2.23 Smoke Extraction Systems
• FSD Circular Letter No. 2/2002, Hot Smoke Test on Smoke Extraction System
• Australian Standard, AS 4391-1999, Smoke Management – Hot Smoke Test

1. Necessity for Carrying Out Hot Smoke Test in Atrium[pic 4]

1. Fire Hazard in Atrium

With large volumetric space joining togther, fire occurs in atrium would have different scenario comparing with those happen in ordinary buildings.

Furthermore, Fire load varies due to decorations or exhitbition boothes in different seasonal festivals or holiday which results in temporary high fire load density. This raises fire hazard in an atrium. The peformance of smoke extraction system would then pays an important role in conservation of safety of occupants in case of fire.

As a result, it is essential to set up a duly testing method for evaluation of performance of smoke extraction system.

1. Objective and Requirement of Hot Smoke Test

Since there are raising number of buildings comprise atrium design in Hong Kong such as Hong Kong Conventional and Exhibition Centre, MegaBox or LangHam Place as shown in APPENDIX A, in order to preserve safety in atrium, attention should be paid on the fire safety measures in atrium such as smoke extraction system.

In view of this, FSD issued a Circular Letter No. 2/2002 in year 2002 stating that in order to ensure the satisfactory installation of the smoke extraction system, HST is necessary to be carried out for evaluating  the performance of such system for compartments with the following features (2):

1. Headroom of 12m or more; or
2. Irregular geometrical dimensions or extraordinary large size.
3. Space Volume bigger than 28,000m3.

It also states that the test will be conducted with reference to the Australian Standard AS 4391-1999 or other equivalent international standards and would be considered acceptable if the following points are complied (3):

1. Adequate smoke clear height;
2. Low level fresh air make-up and high level smoke air extract is properly formed to to maintain smoke flow pattern and achieve “scouring” effect;
3. Proper operation of smoke extraction system in response to fire alarm signal;
4. No significant disperse of smoke to adjoining smoke compartment;
5. No significant smoke build up in “stagnant corners” beneath the smoke layer; and
6. No re-entering of smoke into the building through openings or fresh air intake path.

According to AS 4391-1999, Smoke Management Systems – Hot Smoke Test,  HST method is intended for use as a tool in the commissioning process of a building’s smoke management system to verify that the operation of the system, under simulated test fire conditions, is as approved by the regulatory authority. It is not intended that carrying out a hot smoke test be a mandatory requirement for every installed smoke management system.

By means of conducting HST, performance of smoke extraction system could be evaluated and preserved.

1. Examples of Hot Smoke Test in Hong Kong

In Hong Kong, HST should be carried out according to the following salient points as stated in the FSI Code (4):

1. The temperature of simulated hot air plume should be maintained at about 10℃ below the temperature rating of the ceiling sprinklers to avoid any unwanted actuation of sprinklers or damage to building structures and finished;
2. The size of the test fire should be at least 1 MW or of such size as agreed by the Director of Fire Services;
3. Non-contaminating industrial grade methylated spirit may be used subject to the agreement of the Director of fire Services;
4. Non-toxic oil-based smoke produced by smoke generator may be used subject to the agreement of the Director of Fire Services;
5. The test will be conducted with reference to the Australian Standard AS 4391-1999 or other equivalent international standards.

Project – Hong Kong Conventional and Exhibition Centre Expansion Project (5)

To incorporate further development of HKCEC, expansion project has been implemented between phase I and Phase II. Dynamic smoke extraction system was installed to preserve fire safety in such premises. In order to evaluate the performance of dynamic smoke extract systems in the HKCEC expansion project, hot smoke test was carried out by team comprises members from The Hong Kong Polytechnic University and Harbin Engineering University following the procedures as stated in AS4391-1999 with a fire set up of heat release rate of 2MW which satisfied the specification in FSI with heat release rate higher than 1MW. Photos showing the test set-up and apparatus are attached as APPENDIX B.