C7H8
| Gas | Toluene |
| Formula | C7H8 |
| CAS Number | 108-88-3 |
| Lower Explosive Limit (LEL) | 1.0 Vol.-% |
| Relative density | 3.18  |
| Appearance | Colorless Benzene-like odor |
| Hazards | High flammability Harmful |
The ME1250 Gas Sensor is a remote measuring unit for monitoring gas concentration and is used as a leak detector for explosion protection.
The microprocessor-controlled electronics of the sensor, adapted to the specific properties of the measuring cell, enable fast and reliable signal processing. The measured gas con-centration is transmitted to a Gas Control Panel, which can manage a large number of distributed gas sensors.
Thanks to bus communication, only one cable is required, which can be continued from sensor to sensor. The ME 1250 Gas Sensor is also available with an analogue output signal of 4…20 mA. The measured gas concentration can thereby be processed by other PLC (Programmable Logic Controllers).
The optional relay module expands the ME 1250 Gas Sensor internally with 3 relays for direct switching of signal transmitters without the use of a control panel.
Advantages
- Automatic zero point calibration
- Active noise reduction on the output signal
- Linear measurement signal depending on the gas concentration
- High response sensitivity with short response time
- Selective and reliable measurement with a stable measurement signal and zero point
- Temperature-compensated measurement signal
- Insensitive to other gases
- Insensitive to room temperature and humidity
- No destruction of the measuring cell at high gas concentrations
- Very long service life due to the optical measuring method
Technical Specifications
| Measurement method | Infrared / Optical |  |
| Measuring range | 0…100% LEL | other measuring ranges on request |
| Alarm thresholds | Alarm 1: 20% LEL Alarm 2: 40% LEL | recommendation |
| Lifespan in air | 10 years | according to cell manufacturer |
| Break-in period | 3 min | according to cell manufacturer |
| Response time t90 | 10 sec | |
| Operating voltage | 10…28 VDC | nominal 24 VDC |
| Ambient temperature | -40…+60 °C | |
| Humidity | 20…98% rF | non-condensing |
| Mounting height | 30 cm above floor | heavier than air |
| Casing | Default: Powder-coated aluminum Orange RAL 2004 80 x 125 x 59 mm 500 g | Optional: ABS plastic Light gray RAL 7035 81 x 121 x 56 mm 250 g |
| Cable entry | M20 | |
| EU conformity | CE mark including EMC test |
Versions
| Article code | 12IRB-C7H8-12 | 12IR-C7H8-12 |
|---|---|---|
| Description | Gas Sensor ME 1250 C7H8 Toulene Bus communication | Gas Sensor ME 1250 C7H8 Toulene Analogue |
| Output signal | Bus communication with gas control panel | Analogue 4…20 mA Load max. 800 Ω at 24V input |
| Connection | 4-core cable U72M 1x4x0.6 mm Shielded | 3-core cable U72M 1x4x0.6 mm or CY 0.5 mm2 Shielded |
| Topology | Bus, tree or star topology | Star topology |
| Power | < 1.2 W | < 1.8 W |
Signal Processing
with Gas Control Panel
for PLC processing
without Gas Control Panel
Accessories
| Article Code | Description |
| 1250-REL | Relay module for single sensor ME 1250 |
| 1250-AIR-BOX | Ventilation duct add-on box for gas sensor ME 1250 |
| 1250-AIR-FLOW | Fitting hose connection for gas sensor ME 1250 |
| 1250-SUP | Mounting plate round pillars for gas sensor ME 1250 |
| 1250-SCHUTZ | Sun and weather protection for gas sensor ME 1250 |
Consumables
No wearing parts.
12IR-C7H8-12
