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ColtShaft mechanical shaft system: protecting means-of-escape stairs in residential and fire-fighting stairs

ColtShaft is a mechanical fire-fighting shaft system which provides equivalent performance to a BRE shaft for the ventilation of common corridors and fire fighting lobbies. It can therefore be considered to meet the recommendations of Building Regulations (E&W) Approved Document B, BS 9991 and BS 9999 for ventilation of stair cores.

Under design conditions with the lobby doors open, ColtShaft provides a ventilation rate similar to the BRE shaft, but it also offers the benefit of a much reduced footprint, providing 20% of the BRE Shaft footprint.

Product information

Watch our video which describes how ColtShaft was developed and shows how it works. 

Space saving

ColtShaft requires a shaft with a cross sectional area which can be as small as only 0.6m² compared with 3m² for the BRE shaft or 1.5m² for a natural residential (ADB) shaft.

This represents up to 80% reduction in the floor space required. It opens up the space on each floor, which allows architects to be more creative in their design, and improves the saleable or lettable space for the client. This in turn increases the profits for developers and the income for landlords, and permits more usable space.

Enhanced performance

ColtShaft can perform better than a BRE Shaft since it extracts at a defined rate - this means that it is unaffected by external wind pressures. It is also less susceptible to obstructions to the airflow within the duct.

View our ColtShaft system under test leaflet and video for further information.

The ColtShaft design has been proven by extensive CFD analysis and by empirical tests.

There are two types of ColtShaft, the ColtShaft Variable and the ColtShaft Constant.

ColtShaft Variable system

The ColtShaft Variable incorporates duty and standby variable speed extract fans with inverter drive, linked to pressure sensors within the lobby and corridor at each level via the control panel. A motorised damper or flap is provided between the shaft and the lobby/corridor at each level. A 1 m² ventilator is needed in the stairwell for air inlet.

The pressure sensors maintain acceptable pressure difference between the lobby and stairs, typically at 25Pa.  This ensures that excess pressures do not draw extra smoke past door seals or cause excessive door opening forces.

The ColtShaft Variable system is a LABC Registered System because of its superior performance as proven by CFD, thereby providing prior assurance of Building Control Approval.

ColtShaft Constant system

The preferred design of mechanical shaft for apartment buildings is the ColtShaft Variable. However, not all clients are prepared to make the investment needed for this system. The ColtShaft Constant provides equal or better ventilation, but at the expense of potentially compromising compartmentation and of reverse hanging escape doors to open against the direction of escape. It has a lower initial cost.

The ColtShaft Constant uses a fixed speed fan, sized to provide the full ventilation rate when the stair door is open. To avoid over depressurisation of the lobby or corridor when the doors are closed, an adjustable door closer is provided to the stair door which can be set to allow the door to be pulled open sufficiently to maintain a set pressure difference, normally around 25Pa. To allow this, the doors opening onto the lobby or corridor should be reverse hung to be pulled open by escaping occupants rather than opening in the direction of escape as is the conventional practice.

Environmental ventilation systems – providing added value to a shaft system

The quest for energy efficiency has led to very good insulation in residential buildings. While this is very good for the environment and electricity bills, it is having unintended consequences stair lobbies, corridors and entrance halls, which tend to overheat.

Using the equipment specified to provide smoke control of the common areas, it is possible to provide a simple and effective cross flow ventilation system to extract warm, stale air from these spaces and their ceiling voids.

View our CoolShaft page for further info

We are at your service

We provide a pre-order design service. We also offer complete project management, installation, wiring and commissioning, which means that we take complete responsibility to ensure that the product is in full working order within one package of works.

Please contact us for more information relating to the application, specification, installation or servicing of this product.

Product video

Compliant AOV solution

Colt Extended Corridor solution

This clip shows a CFD model of a Building Regulations compliant dead-end corridor fitted with a conventional AOV. Smoke is shown blue and clear air is shown red. At the start of the video the door opens to allow people to escape and smoke pours out of the apartment and hangs around in the corridor. The video then jumps forward to when the fire brigade arrive to open the door again to fight the fire. The corridor fills with smoke. The corridor remains smoke logged for a long time after the door is re-closed.

This clip shows a CFD model of a non-compliant dead-end corridor provided with an Extended Corridor "Pull" system to compensate for extended travel distances. Smoke is shown blue and clear air is shown red. At the start of the video the door opens to allow people to escape and smoke pours out of the apartment but is quickly cleared. The video then jumps forward to when the fire brigade arrive to open the door again to fight the fire. The corridor fills with smoke but it then clears quickly when the door is re-closed. By comparison with the situation with a conventional AOV, the Colt Extended Corridor "Pull" system provides better conditions for escape and fire-fighting.

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