New Code (at least since 2010) calls for duct sensors to be tested in three ways: sensing of smoke (smoke entry), differential pressure, and sensitivity. The duct detectors in our building are about 30 years old, and haven't been manufactured for about 20, and have historically only been tested using the first of the three. Since they need to be tested for all three now, we have been told that due to age and the fact that the manufacturers specifications for the last two tests is not available, we will need to replace all of the duct sensors. Not cheap. Since the do pass the smoke entry test and do trip the alarm as required, is there any Code reason we can't "grandfather" these in and continue to use them until they fail? Or is this going to be simply a question for our AHJ?