Smokes and Dirt Don’t Mix

We often receive phone calls shortly after a new installation that the fire alarm system is malfunctioning. And, it is often determined that the complaint is a result of dirty smoke detectors.

 
 
 
 
A couple of items of interest to be aware of:

1. Smoke Detectors are an effective method of detecting smoke in the early stages of fire. Most newer spot-type Photoelectronic smoke detectors operate in the principal of light scattering. Spot-type Photoelectronic smoke detectors and with the help of fire panel “intelligence” offer a broad range of smoke sensing capability at a reasonable cost. When you look closer at the photoelectronic principals of operation, a photoelectronic smoke detector is an airborne particle sensor that relies on light scattering into an optical sensor for detection. Whether it is smoke, dust, moisture, bugs, or any other foreign debris — light is scattered.
2. Newer photoelectronic sensors in combination with software do a much better job of eliminating false alarms, however with these enhanced features, some new action items are required to the various trouble alerting features to assure a reliable “ready to protect fire alarm system.” This is no different than today’s newer computer-based cars.
3. As dust and dirt accumulate in the sensor, both integral and panel software will implement algorithms and make adjustments to compensate for the accumulation of dust and dirt particles. However, the sensor and panel software will eventually reach a threshold where they are no longer able to adjust and a trouble alerting signal will be initiated advising of needed attention. These signals can vary from, “Detector Failed Test,” “Invalid Communication,” “Maintenance Alert” to “Maintenance Urgent.” These signals normally result in the fire panel display showing a Trouble condition and sounds the trouble audible in the display.
4. NFPA 72 17.7.11.1 Protection During Construction does provide some guidelines or warning to detectors installed during construction. In summary, a building should have clean smoke detectors when occupancy is granted. However, this may not be the case due to aggressive construction, job phasing or partial occupancy needs. When smoke detectors are installed too early in the construction phases, smoke detectors will be exposed to construction dust and dirt resulting in nuisance “maintenance required” trouble signals. This includes smoke duct detectors installed to the heating and cooling ventilating system. And when this happens, most manufacturers or dealers will not cover this under warranty.
5. Resolving this problem is a quick fix by doing the following:
   1. Calling your service company
   2. Cleaning the sensor with a vacuum or compressed air
   3. Simply replacing the sensor with a new device.
      If your actions are effective, the fire panel should return to normal.
6. Further, newer fire panels do provide end users the ability to read detector sensitivity to determine if your actions truly had a positive impact to the sensors sensitivity. The End User Owners and Dealer should be able to provide instruction on how to perform this function.
7. So, be aware of the condition of your fire panel and don’t be intimidated to give it the attention it is asking for.
8. Remember, “Trouble,” “Supervisory” and then “Detector Maintenance” is not an Alarm — it is a request for service.
9. Your fire panel should always read: “All Systems Normal.” ●