UL Standards free download UL 920001 2021 pdf download – Performance Requirements for Toxic Gas Detectors UL 920001 2021 pdf download - Performance Requirements for Toxic Gas Detectors. 3.25 spot-reading apparatus: apparatus intended to be used for short periods of time as required (typically 5 min or less). 3.26 sample-draw: a method to... 02-09 Download Now