Performance of Home Smoke Alarms - National Institute of ...

Time to Alarm Threshold (s)A7006005004003002001000PE lowPE midPE highION lowION midION highA B C D E F GAlarm LocationMass Concentration (mg/m 3 )C504030201001 10 7MassNumber00 120 240 360 480 600Time (s)7.5 10 65 10 62.5 10 6Number Concentration (particles/cm 3 )Air Temperature ( o C)B403530252050temperature relative humidity 4540353025200 120 240 360 480 600Time (s)Relative Humidity (%)Ion Chamber (volts)D87654Chamber 1Chamber 2Number00 120 240 360 480 600Time (s)1 10 77.5 10 65 10 62.5 10 6Number Concentration (particles/cm 3 )Figure 153. Frying bacon scenario - cast-iron pan, LPG hot plate,no forced flow, burner lit at t=0, bacon in pan at 60 sFigure 155 shows the results for bacon cooked in the aluminum non-stick frying pan heated bythe electric range with no forced air flow. Figure 155A shows the time to reach alarmthresholds. Usually, ionization thresholds were reached before photoelectric thresholds with theexception of the lower threshold at position G. Fewer thresholds were reached in this testcompared to the cast iron frying tests above, even though the bacon was cooked to the samenominal doneness. The temperature rise was about 3 EC over the test time, and again the relativehumidity increased to a peak, then decreased below the initial value by the end of the test.There were two peaks in the number concentration attributed to the method of cooking (i.e.turning the bacon and moving it and pressing it with a spatula), on the order of 4x10 6particles/cm 3 . The mass concentration also experienced two peaks, the early one about 20 mg/m 3and the latter one about 80 mg/m 3 . The ion chamber voltages follow the number concentration166