Posted By J Ridley
My business has approached me regarding the number of the above alarms we are receiving across our sites. This is both unnecessarily disruptive and costly. Most of our incidents appear to be caused by dust, wiring faults, defective heads, condensation from chilled environments, and vehicle exhausts. As a result the business is currently considering fitting a delay accessory to all main fire alarm systems thereby allowing for investigation of the initial alarm to avoid any unnecessary evacuation.

My thought are this - although delay accessories have their place within fire alarm systems i.e multi-level buildings, critical processes, systems that cannot or are difficult to shut down or restart, fires do generally develop in the first 3/4 minutes after ignition. This will be exactly the time that our initial investigation would be carried out and, therefore, raises the risk of personal injury and property damage.

Has anyone out there come across this problem before and if so what did they do as a result and what proved effective and what did not? Is there also a recommend time delay for investigation of fire alarms?

Your help/comments would be most welcome.

Thanks
John

Posted By Heather Collins
Fitting a time delay is simply taking the easy option. You need to investigate each type of false alarm in turn and if possible correct the cause. For example:

Dust/exhaust/steam causing alarm (presumably by setting off smoke detectors?) - replace detector with a rate of rise heat detector.

Faulty detector heads - sort out your system maintenance. A fault on a modern addressable alarm shouldn't cause an evacuation alarm anyway it should cause a fault alarm.

Then when you've corrected as many of the causes as possible, you might consider a time delay, but only if your risk assessment considers it to be appropriate!

We have such a time delay on certain types of activation. For example activation of a break glass point, sprinkler head, gas suppression system ALWAYS sounds the alarm at once. Activation of a smoke detector allows a three minute delay - during which time the alarm sounds in alert mode and certain people rush around investigating - before sounding the evacuate signal. If such a delay is introduced it must be VERY clear who has authority to cancel the alarm and what checks they must carry out first. On our site the rule is if you are in any doubt at all you must let the evacuate sound and only a very few have the authority to cancel anyway.

Posted By Stephan
I agree that the contractors may need to call more often ... you could always go for heat detectors.

Not all panels can be adapted for the delay and if not it is an expensive exercise. 4 MINS IS THE NORM.

Posted By HR71
Hi,
I think you are not having an addressable fire panel (correct me if I am wrong). Way I understood is that due to faults in the system you get fire alarms. Well Wiring faults should not generate a fire alarm if they are wired as per manufacturers specifications. Should that be the case then any wiring faults will show as "faults" in the panel and not as fire alarms. I think this needs to be sorted out first.
You might want to check is the detectors in dusty and places where chilled air supplied, if they could be located away from the dust or air streams.
Defective heads of course will give a couple of false alarms before they go dead and detected by the panel.
For areas where smoke is present you might want to change the detector type to a heat sensitive one rather than an optical smoke type.
Also, you could introduce a preventive maintenance regime for the detectors where you could carry out cleaning if none of the above fails. (I used to do this 2 times a year).

Now as with the delays, There shouldn't be any delay once an alarm is triggered for the first responders at site. Evacuation alarm can be and is set with a time delay in almost every new addressable system. some even allow zoned evacuation.
As per modifications to the fire alarm, I might re-think considering the fail-safe design of such a system. You would want to consider the design of such a system and how it would behave in case of a failure of it's own circuitry. i:e, will it not sound the alarms if the circuitry fails and then, how would the insurance look at it, and was it approved to fix such equipment across the fire panel?
By the way, may i know the brand and model of your panel? Have you thought about an addressable panel with voice address?
Cheers.

Posted By Ashley Wood
I would recommend a detailed audit of your systems. It is common for business to grow and not adapt their fire detection system to the new process, this may be a cause of some of the 'unwanted' alarms. Have the audit done by an independent specialist and not by a fire alarm contractor, for obvious reasons. A detailed audit looking at your process, age of system, maintenance regime, locality of unwanted alarms, time of unwanted alarms, type of systems etc will cost money, but it could save you thousands in the long run.

A few years back we did an audit for a client who was frustrated and on the brink of spending £100k on replacing the systems he thought were causing him a problem. When investigated it was discovered that the system kept going into alarm at specific times through the night. The cause was tracked down to a security guard who was having a smoke in the lift. The building was no smoking. He would do his rounds and then stop the lift and have a smoke. Off went the detector in the lift shaft.

Something is causing the alarms, audit and remove the problem. Time delays are not good and should only be used in exceptional circumstances.