5 Approved Methods for Testing Smoke Detectors

In my last column, I covered sensitivity testing for smoke detectors and when this is required. In this month’s I will discuss approved methods. While I am referencing the 2019 edition, the requirements are identical in the 2016 and just released 2022 editions.

The user of NFPA 72, National Fire Alarm and Signaling Code is directed to Table 14.4.3.2, Testing. This table is found within Chapter 14, Inspection, Testing and Maintenance. There are five allowed methods.

1. Calibrated test method
2. Manufacturer’s calibrated sensitivity test instrument
3. Listed control equipment arranged for the purpose
4. Smoke detector control unit arrangement whereby the detector causes a signal at the control unit when its sensitivity is outside its listed sensitivity range
5. Other calibrated sensitivity test method approved by the authority having jurisdiction

Calibrated test method: Depending on the make and model, a number of conventional detectors have the means in which by inserting a magnet or other means of activation will place the detector into an internal test mode. In most cases the individual conducting the test will observe a number of flashes from a LED on the detector. Depending on the number of flashes will inform the technician if the detector being examined is within range, or outside of the listed range. This may be either too sensitive or not sensitive enough. Typically, this means is found on older detectors.

This method may also be done through the use of a test instrument that is not specifically made for one detector or another, but can be used on any detector. As long as the listed obscuration percentage is known the test instrument will provide an indication that the detector is inside or outside of the prescribed range. The test instrument will inject a control amount of test smoke into a testing cup that is seated next to the detector being tested. The technician needs to make certain that the test cup does not lose it seating against the detector being tested or the test will be required to be repeated. This can be a rather time-consuming test per detector. This means is typically used on older detectors that cannot be tested by one of the allowable methods.

Manufacturer’s calibrated sensitivity test instrument: Also dependent on the manufacturer and model, there may be a special instrument that is to be used with the detector to provide an indication that the detector being tested is within or outside of its listed range. This may be through an optical reader, or through a test lack that is part of the detector. These methods are typically found on newer conventional smoke detectors.

Listed control equipment arranged for the purpose: With the movement from conventional fire alarm control units to addressable and addressable/analog FACP’s and systems, the ease of which a sensitivity test can be conducted has increased. Typically, the control unit is placed in a test or maintenance mode and the technician can run the sensitivity test from the FACP. This may be by individual detector or all smoke detectors that are connected to the system. This test can also be performed remotely as long as the functionally of the system is not affected. In this case, no technician is required to be physically onsite. Either of these means reduce the cost of performing this required test.

Smoke detector control unit arrangement whereby the detector causes a signal at the control unit when its sensitivity is outside its listed sensitivity range: With today’s systems, it is possible to set up the system so that if a detector moves outside of range at any time, a trouble signal will be generated at the control unit. For those systems that are connected to a supervising station, a trouble signal would be transmitted there as well. When this means is used, there is no requirement that a technician performs onsite tests.

When a detector sends in a trouble report, the detector in question is identified and can be serviced. This is the preferred method for systems that I design at this time. It eliminates the need to track when a detector is required to be tested and the time that it takes for a technician to conduct the tests.

Other calibrated sensitivity test method approved by the authority having jurisdiction: The code allows for a performance-based method to be used, as long as it is approved by the AHJ. The means that is used must be calibrated as the means must be able to demonstrate that the detectors that are being inspected are within the required range.

If a smoke detector is found to be outside of its listed range, the code requires that the detector is to be either cleaned and recalibrated or replaced. I personally have found it easier to replace the detector as opposed to the cleaning option.

In closing of this discussion, the sensitivity testing of smoke detectors is an important part of maintaining a system that is operating per its design and as well as reducing and even eliminating the number of unwanted alarms that may be generated from a system. It is a task that must be performed as part of any ITM program.

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