I’m looking for suggestions from career-professionals on behalf of my father. He currently holds a facility maintenance supervisor position and has been directed by his boss to explore options for improving the fire alarm notification coverage in a manufacturing plant. His subordinates are licensed electricians and are certified to work on the fire alarm system. They will be doing any installations under this project as the company wants minimal interactions with their service contractor to keep costs down. So here goes:
During a fire alarm test Monday, it was noted that the alarm signals in the manufacturing plant were difficult to hear, and some workers had to be manually directed to evacuate. The N/As are mostly Simplex 9838 horns mounted upon 4903-9105 retrofit plates. I’d say about 1/4 of the devices are horn-only units. These are mounted all around the exterior of the main plant floor and at regular (yet sparse) intervals on the support columns.
Would it be possible to supplement the existing equipment with new devices to increase coverage? The AHJ is following the complete NFPA 72 2007 and NFPA 70 2005 with very few modifications. My dad is not very well versed in fire alarm systems (as his previous facility was not equipped with one), so any input from the techs would be greatly appreciated.
Keep in mind that it no way am I attempting to suggest specific modifications to this alarm system. I am simply helping him look for alternatives to a complete replacement of the N/A’s.
I’ve seen several different setups in different manufacturing plants - everything from standard “wall mounted” notification to a plant wide air horn used for evacuations. So there really is no standard, at least around here, but keep in mind all these places have been pre-existing systems where some of them have been in service for 30 or so years. Also, just because the local AHJ follows the 2007 code, as long as you are not doing any major renovations you may not be bound by that. Around here, the code applies to when the building was built - so it’s not uncommon to just throw up a couple of extra bells because that’s all that was required back in 1954 when the place was built! So you may be fine with putting in a power supply and adding some strobes and horns to those high noise areas to break through the equipment noise. But this is a summary of what I’ve seen…
1.) 10" bells mounted throughout, some with strobes and other areas with remote strobes - worked pretty well except one area we had to add a couple of more bells due to some new equipment added. I don’t know what it is about bells but they seem to be able to work better than electronic horns in these situations.
2.) Federal Signal Model A sirens located throughout the plant/warehouse (standard notification in the office area and some outlying areas in the plant) - the sirens worked really well and could be heard everywhere without problems, but we did have one siren that wasn’t working so one section of the plant they didn’t hear anything until that was fixed. No visual notification in the plant/warehouse.
3.) 7002T’s located on the outside walls - really old system and I seriously thought given the ambient noise it would be very difficult to hear but they cut through pretty well. Probably not going to be available for a new install but figured I’d throw it out there.
4.) Federal Signal Selectone system - this was actually a new system and we weren’t there for the fire alarm system (working on the sprinklers) but I saw a bunch of Federal Signal Model 300 speakers throughout. If you look on their website it’s probably exactly what they need and the nice thing is that it gives them a PA system out of it too. Seems like EVERY manufacturing plant has a crappy PA system that nobody can hear anyway, so might be a nice upgrade.
Two plants I worked on over the years were very close to Lambda’s examples 2 and 4.
The number one example had a lot of the Federal Signal Selectone sirens connected to a 4100+ miniplex system. They worked very well in this noisy plant. One thing to watch on these is the turn on surge. The spec sheet shows the 24VDC units draw under 1 amp. However, I measured them having a 10 amp turn on surge using a Fluke 87 on 1 ms min/max mode. The surge can sometimes cause issues on power supplies with electronic overload sensing.
The number 4 example used a 4100+ miniplex audio system with the Selectone type horn speakers. No internal amplifiers. This also worked very well in a noisy environment. This one also used the F/A system as PA. A third party 8 channel paging interface went between the F/A system and telephone system. This provided all call paging and zoned paging from any telephone in the building.
The signal needs to be 15dB above ambient but can’t go above 110dB total. Are the workers wearing hearing protection? If so, visual appliances are the way to go. One thing we will do if we can, is turn off the noise when we turn on the fire alarm. ie: we put shunts on the equipment and shut it down if possible… now, in a lot of plants this isn’t possible because suddenly shutting down a food processor for example might require lots of clean up and more importantly you might lose the entire batch being made. So see if it’s a possibility to shut off equipment.
I’ve done a handful of plants with Federal signals, and one with selectone, these devices are NOT cheap, and require a lot of power. Is the current setup horns, or horn strobes? To get complete strobe coverage you’d have to add in a lot of A/V’s probably, and replace the old ones to keep them sync’d. The old ones could also be moved to like, offices or somewhere were sync isn’t an issue.
Are there any clean areas or wash down rooms? Class 2 div 2 (explosion proof) or any areas like that? Those NAC’s get very expensive very quickly.
personally i hate doing plants because it requires so much extra equipment, special considerations, etc.
Thank you all for your replies. They will certainly be taken into consideration.
Plant workers wear company-issued hearing protection at all times. This plant assembles large compressor parts, so there are very few automated machinery besides the lift cranes and welding robots. Shutting those off temporarily during the alarm shouldn’t disrupt the manufacturing process that much at all. Definitely an option to look into.
There are no hazardous or “clean” environments present at this facility. Just a continuous, large (extremely large, actually) open plant area. There is a separate electrostatic paint shop located on site but it is not part of the alarm system under consideration.