Gas Detection (CO, CO2 & H2S)
Carbon Monoxide (CO) General Description
The ALTA® Wireless Carbon Monoxide Sensor measures the amount of Carbon Monoxide (CO) in the air.
Key Features
Measurement Range: 0 to 1000 ppm
Resolution: 1 ppm
Accuracy: ± (5% of reading + 10 ppm)
Response Time: 200 s (63% of actual)
Configurable thresholds for critical condition monitoring
Principles of Operation
Carbon monoxide (CO) is a dangerous odorless gas that is produced when petroleum based fuels are burned. The ALTA Wireless Carbon Monoxide Sensor uses an ultra-low power electrochemical transducer to measure CO. The sensor measures the CO level in ambient air every five seconds and reports the most recent reading, along with temperature and the time-weighted average (TWA) of CO, on every user-configurable Heartbeat or when a threshold is breached.
The temperature measurement is used to compensate for temperature effects on the CO element. The sensor refreshes the TWA calculation every 15 minutes and if the sensor has been running for less than 7.5 hours, TWA will be calculated based on the total time running. For temperature measurements, the sensor momentarily energizes a thermistor in series with a precision resistor. This produces a voltage proportional to temperature that the sensor converts into a digital temperature value. This measurement is then sent to the gateway, making the data available in iMonnit or another approved data service.
Carbon Dioxide (CO2) General Description
The ALTA Wireless Carbon Dioxide Sensor uses a low-power high-performance carbon dioxide (CO2) sensing element to measure the amount of CO2 in ambient air and report instantaneous and time-weighted average (TWA) readings.
Key Features
Measurement Range: 0 to 10,000 ppm CO2
Resolution: 1 ppm
Accuracy: +/- 45 ppm + 3% of reading
Data:
- Instantaneous CO2
- 8-hour time-weighted average (TWA) of CO2
- Configurable thresholds for critical condition monitoring
- Configurable auto-calibration
Principles of Operation
The ALTA Wireless Carbon Dioxide Sensor measures the CO2 level in the air using a non-dispersive infrared (NDIR) sensing element. The sensor reports data from the most recent measurement every user-configurable Heartbeat (report interval). This measurement is then sent to the gateway, making the data available in iMonnit or other approved data services.
The sensor also produces 8-hour TWA data by accumulating eight hours of instantaneous CO2 readings and averaging them together.
Hydrogen Sulfide (H2S) General Description
The ALTA® Wireless Hydrogen Sulfide Sensor measures Hydrogen Sulfide (H2S) before it becomes a more serious hazard.
Key Features
Measures both instantaneous and time-weighted average (TWA) of H2S gas levels, temperature compensated
Measurement Range: 0 to 50 ppm
Resolution: 0.1 ppm
Accuracy: ± (5% of reading + 2 ppm)
Response Time: 200 s (63% of actual)
Configurable thresholds for critical condition monitoring
Principles of Operation
Hydrogen Sulfide (H2S) is a dangerous, pungent gas that is often present in petroleum drilling operations or related to sewage (swamp gas). The ALTA Wireless H2S Sensor utilizes an ultralow power, electrochemical transducer to measure H2S. The sensor measures the H2S level in ambient air every five seconds and reports the most recent reading, along with temperature and TWA of H2S, on every user-configurable Heartbeat or when a threshold is breached. The temperature measurement is used to compensate for temperature effects on the H2S element.
The sensor refreshes the TWA calculation every 15 minutes. If the sensor has been running for less than 7.5 hours, TWA will be calculated based on total time running. For temperature measurements, the sensor momentarily energizes a thermistor in series with a precision resistor. This produces a voltage proportional to the temperature that the sensor converts into a digital temperature value. This measurement is then sent to the gateway, making the data available in iMonnit or another approved data service.
Features of Monnit ALTA Sensors
Wireless range of 2,000+ feet through 18+ walls1
Frequency-Hopping Spread Spectrum (FHSS)
Best-in-class interference immunity
Best-in-class power management for longer battery life2
Encrypt-RF® Security (Diffie-Hellman Key Exchange + Advanced Encryption Standard (AES)-128 Cipher Block Chaining (CBC) for sensor data messages)
Sensor logs 2000 to 4000 readings if the gateway connection is lost (non-volatile flash, persists through power cycling):
10-minute Heartbeats = ~ 22 days
2-hour Heartbeats = ~ 266 days
Automatic over-the-air updates to sensor firmware (future-proof)
Free iMonnit Basic Online Wireless Sensor Monitoring and Notification System to configure sensors, view data, and send alerts via SMS text, email, and voice call
1 Actual range may vary depending on the environment and gateway.
2 Battery life is determined by the sensor reporting frequency and other variables. Other power options are also available
