Several Honeywell MIDAS® cartridges can be configured to read a number of different gases based on a common chemical family. Actual details for the sensor detection range are included in the sensor cartridge specification sheet and the MIDAS® technical manual. MIDAS® sensor cartridges can be ordered as part of a Kit with the universal MIDAS® transmitter, or as a replacement part. The detectable range is listed. With the exception of O2 (where ambient concentration is typically 20.9%), the sensors will display zero when no gas is present. All Cartridges with the format MIDAS-E-XXX are supplied with a 2 year (24 month) warranty.
| Gas Measured | Measured Arsine (AsH3) |
| Cartridge Part Number | MIDAS-E-ASH | 2 year extended warranty |
| Sensor Technology | 3 electrode electrochemical cell |
| Measuring Range (ppm) | AsH3 | 0 – 0.2 ppm |
| Minimum Alarm 1 Set Point | 0.025 ppm |
| Repeatability | < ± 2% of measured value |
| Linearity | < ± 10% of measured value |
| Response Time t62.5 | < 15 seconds |
| Sensor Cartridge Life Expectancy | ≥ 24 months under typical application conditions |
| Operating Temperature | 0°C to +40°C (32°F to 104°F) |
| Effect of Temperature | Zero | < ± 0.004 ppm / °C (0° to 40°C) |
| Sensitivity | < ± 0.9% of measured value / °C |
| Operating Humidity (continuous) | 10 – 95% rH non-condensing |
| Effect of Humidity | Zero | Initial short term drift at abrupt rH change (< 0.001 ppm / % rH) |
| Sensitivity | < ± 0.2% of measured value / % rH |
| Operating Pressure | 90 – 110kPa |
| Effect of Position | No effect in typical application |
| Long Term Drift | Zero | < 0.05 ppm / year |
| Sensitivity | < 5% of measured value / 6 months |
| Calibration Gas | Arsine (AsH3) |
| Challenge Gas (Bump Test) | Phosphine (PH3) |
| Warm Up Time | < 20 minutes |
| Storage Temperature | +5°C to +25°C (+41°F to +77°F) |
| Calibration |
| AsH3 | Range | LAL |
| 0-0.2 ppm | 0.025 ppm |
| GeH4 | 0-0.8 ppm | 0.095 ppm |
Cross Sensitivities
Each Midas sensor is potentially cross sensitive to other gases and this may cause a gas reading when exposed to other gases than those originally designated. The table below presents typical readings that will be observed when a new sensor cartridge is exposed to the cross sensitive gas (or a mixture of gases containing the cross sensitive species).
| Gas / Vapor | Chemical Formula | Concentration applied (ppm) | Reading (ppm AsH3) |
| Ammonia | NH3 | 108 | <0.1 |
| Carbon Dioxide | CO2 | 5,000 | 0 |
| Carbon Monoxide | CO | 85 | 0 |
| Chlorine | CI2 | TBD | <-0.05 |
| Diborane | B2H6 | 0.1 | 0.05 |
| Disilane | Si2H6 | 0.27 | 0.12 |
| Germane | GeH4 | 0.27 | 0.05 |
| Hydrogen | H2 | 3100 | <-0.05 |
| Hydrogen Chloride | HCI | 7.9 | 0 |
| Hydrogen Cyanide | HCN | 3.6 | 0.2 |
| Hydrogen Fluoride | HF | 7.2 | 0 |
| Hydrogen Selenide | H2Se | 0.8 | 0.24 |
| Hydrogen Sulfide | H2S | 18.2 | 0 |
| Iso Propanol | C3H2OH | 20,000 | 0 |
| Methane | CH4 | 18,000 | 0 |
| Nitrogen Dioxide | NO2 | 10 | -2.2 |
| Phosphine | PH3 | 0.1 | 0.12 |
| Silane | SIH4 | 0.3 | 0.05 |
| Sulfur Dioxide | SO2 | 17.8 | 0 |
RKI GX-3R / GX-3R Pro 81-GX3RCO Calibration Kit, 103L cyl CO 50 ppm / CH4 50% LEL / O2 12% in N2
1 × $388.50 