

Extech SD800 CO₂, Humidity and Temperature Data Logger
The SD800 is a versatile indoor air quality datalogger that simultaneously measures carbon dioxide (CO₂), relative humidity, and temperature. It logs the data to an SD card in Excel format with date and time stamps, and supports selectable sampling intervals, making it ideal for long-term monitoring of air quality in buildings, schools, offices, and laboratories.
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Description
The SD800 is designed for robust, continuous monitoring of indoor environmental conditions. Its integrated dual-wavelength NDIR CO₂ sensor is maintenance-free and capable of tracking CO₂ levels from 0 to 4,000 ppm. In parallel, it monitors ambient temperature and relative humidity, giving a full picture of indoor air health.
A triple-line LCD lets you view CO₂, humidity, and temperature all at once. The unit supports programmable logging intervals—from as fast as every 5 seconds to as slow as every 600 seconds (10 minutes), plus an automatic mode. Logged data are saved on an SD card in Excel-compatible format with timestamps for easy transfer and analysis.
The SD800 comes with its own probe (via cable) for CO₂ measurement, as well as internal sensors for humidity and temperature. It is powered either by a universal AC adaptor or by six AAA batteries (for clock backup and portable use). The housing supports mounting, and the unit features an RS-232 interface for streaming data to a PC if needed.
In typical operation, the CO₂ sensor responds within about 2 minutes to 63% of the change. The measurement ranges are: CO₂ (0–4,000 ppm), temperature (0 to 50 °C), and humidity (10% to 90% RH). The SD800 is compact and portable, weighing around 282 g, and fits dimensions of roughly 132 × 80 × 32 mm.
Features
- Triple-Parameter Monitoring — Measures CO₂, temperature, and humidity simultaneously.
- Maintenance-Free CO₂ Sensor — Dual-wavelength NDIR design requiring minimal upkeep.
- Data Logging to SD Card — Records timestamped data in Excel format for PC export.
- Selectable Sampling Rates — Options from 5, 10, 30, 60, 120, 300, 600 seconds, or Auto.
- Wide Measurement Ranges — CO₂: 0–4,000 ppm; Temp: 0–50 °C; Humidity: 10–90% RH.
- Responsive CO₂ Sensor — Typical response under 2 minutes to 63% step change.
- Power Flexibility — Operates via AC adaptor or six AAA batteries (for clock backup).
- RS-232 Interface — Allows live data streaming to a PC or data acquisition system.
- Compact & Portable — Lightweight design with mounting options.
- Triple LCD Display — Shows all three measured parameters at once for convenient monitoring.
Includes
- Six AAA batteries
- 2G SD memory card
- Universal AC adaptor
- Mounting bracket





