People often ask us whether they can use fire doors as vents into smoke shafts. The answer to that question is no. There are many reasons why, but the primary reason is due to air leakage. All smoke vents are required to undergo air leakage testing - this is to prevent smoke spreading between fire compartments via the smoke shaft. However, this is a particularly potent issue when we come to pressure differential or mechanical systems.
Due to the much higher pressures involved in pressure differential systems, air leakage becomes all the more critical. That’s why in pressure differential systems we have to use smoke control dampers, rather than any other type of vent.
I’m now going to explain which legislation and guidance requires us to use smoke control dampers:
Firstly, we have to turn to Approved Document B, Volume 1. Section 3, subsection 3.54 states that:
‘Guidance on the design of smoke control systems that use pressure differentials is available in BS EN 12101-6.’
When we look to BS EN 12101-6:2005, in section 11, subsection 188.8.131.52 it states that:
‘If different pressurized or depressurized zones are connected to the same fan or set of fans by a common system of ductwork and/or shafts, smoke control dampers shall be used.’
In order to find out about smoke control dampers, we look to BS 9999:2017, section 6, subsection 27.1.3 which states the following:
‘Where a mechanical smoke ventilation system uses a shaft, it should meet the following recommendations. 1) The top of the lobby vent should be located as close to the ceiling of the lobby as is practicable, and should be at least as high as the top of the door connecting the lobby to the stairwell. 2) The lobby vents, in the closed position, should either: i) have a minimum fire and smoke resistance performance of 60 min and a leakage rate no greater than 200 m3/h/m2 when tested in accordance with BS EN 1366-2; or ii) be in accordance with BS EN 12101-8.’
Finally, the latest revision of the Smoke Control Association guidance, section 8.2, subsection 8.2.2 states clearly:
‘Products should be CE marked to BS EN 12101 Part 8.’
Now you know why you need a smoke control damper, it’s also important to know what sort of damper you need.
When you’re looking at a Declaration of Performance for a damper, you should see a ‘code’ like this:
EI 120 (vew i ↔ o)S 1000 C10000 AA multi
This is formed from BS EN 12101-8 4.3.3 and 4.4.3. Here's a high-level overview of what that means:
The E stands for integrity
The I stands for thermal insulation
We can see with this example that the damper has integrity and insulation of 120.
The ‘vew’ means that the product is suitable for vertical installation in a wall. ‘Ved’ would mean that the product was suitable for vertical installation in a duct. ‘Vedw’ would mean that the product is suitable for vertical installation in both walls and ducts.
The ‘how’ means that the product is suitable for horizontal installation in a wall. ‘Hod’ would mean that the product is suitable for horizontal installation in a duct. ‘Hodw’ means the product is suitable for horizontal installation in both walls and ducts.
The addition of the symbols (i>o), (o>i) or (i<->o) indicate whether the damper has been tested and fulfills the requirements from the inside only, the outside only or from both sides.
The S means that the damper satisfactorily meets the leakage requirements. The addition of 500, 1000, or 1500 indicates the suitability of use up to these underpressures.
The C10000 means the damper has been tested for 10,000 cycles for comfort ventilation - this means that the damper can be used as part of an environmental cooling system.
‘AA’ stands for Automatic Activation. ‘MA’ stands for Manual Activation
Multi means that the product is suitable for smoke control systems dealing with multiple compartments.
That’s a whistle-stop overview of some of the key regulations around what’s known as a ‘dash eight’ damper.