The AS-300 fixed harmful toxic gas detector is a toxic and harmful gas detector that can continuously and online detect the concentration of toxic and harmful gases in the air. The instrument adopts the electrochemical principle and can output the real-time gas data monitored on site through 4-20mA signals or RS485 signals. It is a standard three-wire fixed toxic and harmful gas detection instrument with LCD on-site display and plug-and-play sensor replacement, meeting the application requirements of different industries.
The AS-300 fixed harmful toxic gas detector is a toxic and harmful gas detector that can continuously and online detect the concentration of toxic and harmful gases in the air. The instrument adopts the electrochemical principle and can output the real-time gas data monitored on site through 4-20mA signals or RS485 signals. It is a standard three-wire fixed toxic and harmful gas detection instrument with LCD on-site display and plug-and-play sensor replacement, meeting the application requirements of different industries.

The industries such as petroleum, chemical, metallurgy, environmental protection, paper-making, municipal, biochemical medicine and water treatment.
●Built-in temperature compensation circuit for accurate measurement
●Designed with cover-free style, infrared remote control calibration,operation
●Cast aluminum shell, suitable for various industrial environments
●Easy to install and maintain, sensor replacement on site (plug and play)
●Multiple range options can meet requirements of customers
●Standard three-wire 4-20mA signal output or RS485 output, compatible with DCS or PLC system
● Field level-2 sound and light alarms, relay output (with the external equipment such as external exhaust connected)
Principle of detection | Electrochemistry |
Gas for detection | Toxic and harmful gases (see gas list for details) |
Repeatability | ≤±3% |
T90 reaction time | <60s(NH3<150s) |
Polarization time: | 24h |
Power supply: | 24VDC |
Power consumption | <2.5W |
Calibration | Every 4-8 months |
Reset | Every 3-6 months |
User interface | Infrared remote control |
Working temperature | -40°C-70°C (limit); -20°C-50°C (typical) |
Operating pressure | Standard atmospheric pressure ±10% |
Working humidity | 0-95%RH (no condensation) |
Output signa | Three-wire system 4-20mA , RS485 |
Display | Field LCD display |
Explosion-proof class | Ex db IIC T6 Gb/Ex tb IIIC T80℃ Db |
Protection grade | IP66 |
Standard configuration | Detector host;Audible-visual warning light;Remote control;Instructions |
Accessories installation | Mounting bracket;Rain cover |
Serial No. | Name | Chemical formula | Standard range | Highest range |
1 | Ammonia | NH3 | 0-100PPM | 0-500PPM |
2 | Carbon monoxide | CO | 0-1000PPM | 0-2000PPM |
3 | Sulfur dioxide | SO2 | 0-20PPM | 0-150PPM |
4 | Formaldehyde | CH2O | 0-10PPM | 0-500PPM |
5 | Ethylene oxide | ETO | 0-10PPM | 0-500PPM |
6 | Vinyl chloride | C2H3CL | 0-10PPM | 0-500PPM |
7 | Chlorine | CL2 | 0-10PPM | 0-50PPM |
8 | Hydrogen sulfide | H2S | 0-50PPM | 0-100PPM |
9 | Hydrogen chloride | HCL | 0-20PPM | 0-200PPM |
10 | Hydrogen cyanide | HCN | 0-20PPM | 0-100PPM |
11 | Nitric oxide | NO | 0-100PPM | 0-1000PPM |
12 | Nitrogen dioxide | NO2 | 0-20PPM | 0-150PPM |
13 | Oxygen | O2 | 0-25%VOL | 0-30%VOL |
14 | Ozone | O3 | 0-5PPM | 0-100PPM |
15 | Acrylonitrile | C3H3N | 0-10PPM | 0-100PPM |
16 | Ethylene | C2H4 | 0-10PPM | 0-1500PPM |
17 | Chlorine dioxide | CLO2 | 0-2PPM | 0-5PPM |
For more gas types, please contact local sales distributors .