Haze and Fire Alarms

[wirralmatt]

I’ve been using the same preset haze settings, in the same room, at similar temperatures for over a year. I know I can get away with 45% on the pump setting of the Hazer without setting fire alarms off. So I run it at 35% to be safe.

 

This morning the Hazer set off the fire alarm after an hour. Same settings. Same temp. Same Hazer. Same fluid.

 

Is there something I’ve missed that could have meant the alarm went off when it normally wouldn’t?

[gyro_gearloose]

It depends what type of detectors you’ve got, but the chances are a layer of haze juice has built up on them. This will make them more sensitive to what little amount of haze you’ve been using. Don’t be tempted to clean the detectors yourself though as you might make the situation worse.

[adam2]

Random variations in air movement I suspect. The degree to which haze builds up will depend on the degree of air changes in the space. That in turn will depend on variations in wind speed and direction, and the chance opening of doors and windows elsewhere in the premises. Both are more or less random.

 

Other possibilities include variations in the "strength" of the haze fluid used, mains voltage variations, and apparently trivial alterations in the placement or directing of the haze machine, or the layout of any scenery or furniture.

 

IME any use of any form of haze or smoke in a space fitted with smoke detectors carries some risk of triggering the alarm. It would be preferable for performance areas to have installed means of isolating smoke detectors during performances. Smoke detectors do not serve any useful purpose in OCCUPIED performance spaces.

 

 

 

[kerry davies]

Pretty hot down here right now, got windows open I never normally have. Outer doors are jammed open for a draught.

 

The effects of ventilation conditions, build up of residue, temperature of fluid in reservoir, levels of Saharan dust in the air.... all may make a difference and running a test later on when it is cooler and airflows are closer to normal will reveal more.

 

Adam is right enough. Perhaps they need isolating in future?

[bigclive]

It could be that if the room was quiet then a layer of warm and cold air caused the effect of a layer of fog floating at a fixed height above the floor.

 

Depending on the type of building and room it might be a good idea to get the detector heads replaced with either rate-of-rise thermal detectors (they detect a sudden temperature increase) or a combined detector with heat and smoke detection, that uses an algorithm to decide if a real fire has occurred.

[Jivemaster]

Realistically it's a smoke detector so it will detect smoke and haze, it's only good luck that so far it's infrequent. Ultimately rooms with a smoke detector are unfit for entertainment use because someone sooner or later will make smoke in there. LOTS of better detectors are available and there are lots of ways of putting systems in either "double tap" (two detectors need to alarm for the system to trigger) or in full manual operation for the duration of a show.

[wirralmatt]

Thanks for all the advice and ideas. I will have a look at the different detector head options. Thanks everyone.

[Richard CSL]

if you speak with your local fire officer he will allow you to disable the system only if the room is in use, sometimes they will allow you to put covers over the detectors when the room is in use, again speak with your local fire officer.

[gyro_gearloose]

Our system at work has a ‘performance override’ option, which disables the smoke detectors over stage and in the auditorium. We also have rate of rise temperature detectors, which don’t get disabled. As others have said, speak to your fire officer. A system like ours might be the best solution for you.