DA-750 detects leakage of various toxic or combustible gases leaked from industrial areas for gas producers, gas users, gas reservoirs, gas by-producers, and so on, in order to prevent any accidents in advance. Built-in micro pump suctions gas continuously which is effective gas sampling especially for closed area. DA-750 converts digital signal into the 4-20㎃ standard current signal for output signal which can be transmitted to various external devices such as PLC, DDC, RECODER, and so on to construct the gas monitoring system more extensive as well as more comprehensive. DA-750 provides RS-485 communication signal and gas leakage alarm signal by relay contact output. Besides, DA-750 has DC 4-20mA standard output which realizes max 2500m long distance output signal transmission from sensor to receiver and RS-485 communication signal which realizes max 1000m long distance signal transmission.