Extech dissolved oxygen meter and datalogger extech sdl150 the extech sdl150 dissolved oxygen meter and data logger records data on an sd card in microsoft excel reg format for easy transfer to a pc for analysis it measures dissolved oxygen from 0 to 20 0mg l and 0 to 100 0 oxygen plus temperature from 0 to 50 deg c 32 to 122 deg f the sdl150 features automatic temperature atc compensation from 0 to 50 deg c via a temperature sensor built into the polarographic type oxygen probe the