Open or closed protocol in smoke ventilation: why now?

Posted by Conor Logan on 11/11/11 15:03

OPV Control panel - Open or closed protocol in smoke ventilationDiscussions about the relative merits of open or closed control protocols have been ongoing in the fire alarm and smoke detection markets for years but up until recently, this debate has not really affected smoke ventilation systems, and actually it’s a surprise that it has arisen now.

One important task when trying to choose a fire alarm system, whose function is simple, is to ensure that smoke is detected efficiently and that, when it is, the fire alarm goes off. However, a smoke ventilation system has to do far more.

Why is this discussion happening now? What’s changed?

The smoke ventilation market has changed considerably over the past 15 years. Up until the late 90s, most smoke ventilation systems comprised large areas of natural vents which generally either all opened or all closed in zones. Controls were relatively simple and were predominantly pneumatic, requiring a network of copper pipework, solenoid panels and a central compressor, with springs and fusible links on the ventilators providing a failsafe mode of operation.

In the mid-90s, a big change was brought about by the introduction of a groundbreaking addressable control system called OPV, developed by Colt.  This control system relies on a full suite of addressable smoke and heat detectors, call points and override devices, providing a robust and highly flexible solution perfectly adapted to the evolving requirements of the building industry. This was no ordinary control system, it included a highly developed degree of intelligence and contained robust failure protection.

In more recent years, the smoke control market has changed with an upsurge of large-scale residential schemes and commercial towers with fire fighting shafts requiring much more sophisticated control systems with highly complex sequences of operation for their smoke ventilation systems.

How do current systems meet demands?

In order to meet the demands of these projects, smoke control systems have had to be able to cross fire compartments, without compromising compartmentation and the fire resistant properties of walls and floors. For example, if a fire occurs on one level in a multi-storey residential scheme, a damper needs to open on the fire floor to allow smoke to be vented to outside, while dampers on all the other floors must remain closed to prevent smoke and fire spreading to other levels.

The control sequence is then further complicated because once one floor has received an alarm and reacted, the system must then ‘lock out’ any other alarm signals to stop multiple levels opening and risking smoke spread from the floor of origin. In addition, the fire service needs the capability of a central override system to either instigate the system operation or cancel and re-assign the system operation.

All these different control sequences become much easier to control using a programmable operating system like the Colt OPV network.

However, just like mobile phones and computers, technology has moved on and the time has come to investigate where we should go from here. Currently, the debate within the industry is mainly focusing on ways to adapt existing technologies for smoke ventilation applications. These technologies fall into two categories: HVAC/BMS control systems and Fire Alarm Control Systems. At Colt we have opted to stay on the path we started in the 90s, developing our own control system.

In my next blog post I look at the key features that a smoke ventilation control system needs to have.

If you would like to know more about the pros and cons of open and closed protocols for fire alarm and smoke detection systems, you can read my previous article "Open or Closed Protocol in Fire Systems: which is best?", where you will also find a very useful white paper on the subject.

Associated blogs:

Conor LoganConor Logan is a Technical Manager of Colt UK, Smoke and Climate Control Division. Designing innovative smoke control and HVAC systems Conor is also Chairman of the Smoke Control Association.

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Topics: Smoke Control, Smoke ventilation