The GMD/W20 series of carbon dioxide transmitters requires calibration only every five years. These devices feature the silicon-based CARBOCAP sensor, which provides stability, accuracy, and temperature dependence over a broad temperature range. They measure carbon dioxide from 0 to 2000 ppm, though they can be calibrated for other ranges. At 20°C, including nonlinearity and calibration uncertainty, accuracy is less than ±20 ppm + 1.5% of the reading. Their long-term stability is less than ±100 ppm every five years. Response time is less than 60 seconds, from a 10% to a 90% response. The series includes the standard 0- to 20-mA, 4- to 20-mA, and 0- to 10-V outputs, along with two other options—a LonWorks interface and a relay output. Contact the manufacturer for pricing and availability information.
Vaisala Inc., 100 Commerce Way, Woburn, MA 01801; (781) 933-4500; fax (781) 933-8029.