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

A2ARHCBA1DEA3FGU+V+Figure 141. Schematic of the manufactured home for nuisance testing6.2.1 Aerosol InstrumentsTwo portable aerosol instruments were used to gather aerosol number and mass concentrationsduring the tests. Number concentration was recorded with a TSI model 3007 portablecondensation particle counter (CPC). This instrument is capable of counting particles greaterthan 10 nm in diameter up to concentrations of 5x10 5 particles/cm 3 with an uncertainty of 10 %of the reading. The upper concentration range of the instrument is insufficient for many fire andnuisance conditions so the air sample was diluted with a fixed amount of clean air prior toentering the CPC. The air sample was drawn through a 1.5 m long, 6 mm ID PVC tube (Tygonbrand, which is recognized to have low electrostatic particle loss characteristics.) to a laminarflow element that was attached to one branch of a “Y” tube fitting. The other branch of thefitting was attached to a HEPA filter, while the main branch was attached to the inlet of the CPC.The CPC internal pump draws air from the sampling tube and clean (particle-free) air throughthe filter into the unit. With this arrangement, approximately a 20 to 1 dilution of the airsample is achieved. The dilution ratio for each test was obtained by computing the ratio ofundiluted to diluted background room aerosol. The uncertainty in the dilution ratio is estimatedto be 2%. A TSI model 8520 “Dustrak” portable aerosol mass monitor was used to gather theaerosol mass concentration. This device is a light scattering photometer that analyzes the lightscattered at an angle of 90E from particles flowing through the device. Its default calibration isset to the respirable fraction of standard ISO 12103-1 A1 test dust. It has a range from151