... instrument advanced technology, excellent performance, high stability, can detect the gas variety, with recovery factory default Settings and since diagnosis ... method Concentration unit:ppm,%VOL,%LEL,mg/m3 Acousto-optic alarm means:, vibration Working temperature: - 40 ~ 70 °C Work ... wording of "screen Alarm" are flashing, if it's electricity shortage, Power icon flash, if can't detect sensor, display ...