Smoke detectors frequently contaminated by oil mist in plant

[kurnal]

An industrial plant situated in a confined space currently has apollo optical detectors as apart of an addressable alarm system, the 4 detectors are essential for life safety but require very frequent replacement due to contamination by oil mist.

Whilst efforts are being made to reduce the oil mist for health reasons please can anyone recommend any type of detector that may be more resilient to this enviroment? Would beams be any less problematic do you think? There is never any visible oil mist but after a month or so the detectors are very oily and generating faults or unwanted signals.

[John Webb]

Beam units could have the advantage of giving warning of pollution through diminished light returns - and with an addressable system you could give a 'contamination' alarm. Someone could then go out and wipe the window(s) of the unit(s) to restore the light? Sounds better than having to replace heads all the time.

Could you take this a bit further however and provide the beam unit with either remotely operated wipers on the window (as with some CCTV housings) or perhaps an airline feeding into a short collar around the lens to keep contaminates away from the window in the first place?

[nearlythere]

Sounds like a similar problem I had one time with an automatic spray booth which was prone to going on fire. Only solution at the time was to change detection to heat and cover head with cling film.
At least if there was a fire it would penetrate cling film and operate head. Weekly routine was to replace cling film with clean sheet to prevent excessive build up of paint.

[Midland Retty]

From memory I recall a detector manufactured by Honeywell called a "HARSH" smoke detector.

It has an integral fan and filter system and the manufacturers claim its ideal for dirty and wet environments. Its perhaps worth a look if only to rule it out as unsuitable.

Not sure of the cost and how often filters would need to be changed.