NFPA 270 Standard Test Method for Measurement of Smoke Obscuration Using a Conical Radiant Source in a Single Closed Chamber, 2002 ed. http://www.baibiao.net/picture/18123144995.pdf, (Std: Tst Meth for Meas of Smoke Obscuration Using a Conical Rad Source in a Single Closed Chamber - Amer) {282 NFC}