The fire is out, the whole fire detection and alarm system worked perfectly. The fire service attended and may have already left. Yet there’s a room on your site that, because of the fire, is fatal to enter. You have no way of knowing and are sending occupants back in to a potentially deadly situation.

The reason is carbon monoxide (CO), a colourless, odourless, tasteless gas which, in sufficient concentrations, can cause serious brain injury and death.  
CO is generally recognised as an unwanted by-product of malfunctioning or incorrectly ventilated commercial and domestic fossil fuel burning appliances.  However, it can also be generated following the combustion of specific materials during a building fire. As such it should be considered as a contributing factor in fire associated deaths.  

CO affects the haemoglobin in the blood. It is highly toxic above 35ppm and the effects are cumulative over short periods of time. You don’t have to spend time in a room with high concentrations to be affected. Simply inhaling small quantities of CO can adjust blood chemistry to potentially harmful levels and repeatedly visiting an area containing the gas compounds the effect. The way CO affects the body means it is very easy to be quickly overcome by the gas, and as a result, serious injury or death can occur.

Currently, under European standards, there is no requirement for CO detection to be included as part of a fire detection system. In America, the story is very different and a spate of both fire and non-fire-related incidents have led US authorities to push for CO detection to now be included in most commercial buildings both new and old. This mandate has led to a change to their standards including setting out how these devices should be connected to, reported on, and managed by a building’s fire system.

It is my belief that the EN world cannot be left behind and must embrace the changes American standards bodies are making by translating them into our own guidance. 
“Hang on” you may say, “CO detection has been part of commercial fire detection and alarm systems for many years” and you’d be right, but these specialist devices are strategically placed in suitable areas to detect a fire, in the same way a smoke or heat detector is used. They have much higher sensitivity settings (looking for low concentration levels measured in parts per million PPM) than those required for CO life safety detection, which is the case we are discussing here. 

The CO detectors used for life safety (let’s call them CO-LS to avoid confusion) look for much higher (gas) concentration thresholds to indicate danger to life if inhaled. They were traditionally standalone devices but are increasingly being integrated into domestic standalone smoke alarms as ‘combination smoke CO (fire/life safety) alarm devices’.
Currently, the US standard only mandates commercial CO-LS detection in sleeping areas and, or, where CO can be produced and accumulated. These areas include newly constructed day care centres, lodging and rooming houses, hotels, dormitories and apartment buildings, with some exceptions. The roadmap for mandated sites is growing and it’s clear that the direction of travel is for CO detection to become part of the commercial fire system specification.

Given that CO-LS is now commonly installed as part of the fire system in the US, but has a very different function (i.e. not to detect fires), the NFPA 720 standard for CO detectors was recently updated to mandate how CO-LS detection interfaces are reported and managed on the fire system.

In the US, Trouble is a synonym of our Fault, while Supervisory relates to something like warning or pre-alarm. 

NFPA 720 requires: “CO alarm signals to be distinct and “descriptively annunciated” from fire alarm, CO supervisory and CO trouble signals. Furthermore, the CO alarm signal should take precedence over supervisory or trouble signals. The actuation of a CO detector or system should be distinctly indicated as a CO alarm signal.

“CO detector trouble signals must be indicated visually and audibly at the control panel and supervising station. Therefore, the CO detector must have a means to signal trouble conditions to the control panel, such as a sensor failure or sensor end-of-life signal.”
This means that when CO detectors are connected to a fire panel, they need to be handled differently. The reporting of CO detection is elevated above the other signals the fire panel may action and must have its own distinct warnings. Crucially CO is no longer reported as fire alarm but as its own distinct ‘Life Safety’ category. Again the direction of flow is away from dumb conventional devices to intelligent CO-LS management as part of the fire system.

It may be hard for us in Europe to hear, but the NFPA standards often lead the way for the industry. If nothing else, the US market is the world’s biggest and regional codes, such as in NYC, are among the strictest anywhere. UL is an aggressive and growing standard which anyone selling EN devices outside Europe will need to be aware of. 

It’s worth noting that UL is also ahead of EN in the methods used to wake people from sleep, with several States mandating the use of 520 Hz audio tones, often in conjunction with CO-LS detectors. This will also arrive on our shores eventually and we should act now, but that this is an article in its own right.

In my opinion we need to act now to get CO for life safety included in the EN standards for fire systems as soon as possible, because it is the right thing to do for the future of the EN standard, but mainly because it will save lives.

The Future?
It’s also worth noting that CO Fire detector standard EN54-26:2015 was published earlier this year. This means that any CO fire detectors on the market must be in accordance with this within 48 months (typical) and BS 5839 only refers to CO for fire detection. 

There doesn’t appear to be any work items in CEN or ISO on this topic and even if it were accepted and work started today, it would be unlikely that a CO-LS standard would be out with mandatory product conformity until 2019 at the earliest.

The better news is that there have been discussions between CEN/TC72 and CLC/TC 216 which have led to a joint working group to draft European standards in this area. While we may be somewhat behind our American colleagues, the EU is starting to catch up.