Carbon-dioxide transmitters are self calibrating and have long life
GE Sensing’s Telaire carbon-dioxide transmitters are aimed at indoor-air-quality and energy-conservation applications. Duct-mounted Ventostat T8031/T8041 units and the wall-mounted Airestat T5000 Series are described as offering accuracy and versatility at an affordable price. They are easy to install, simple to use and retain accuracy over their expected life using Telaire’s patented automatic calibration technology. The Ventostat T8031 duct-mounted carbon-dioxide transmitter is said to be one of the smallest such carbon-dioxide sensors on the market. Its modest form factor accommodates 15 cm-diameter return-air ducts and uses the T8041 duct-mounted probe to measure carbon-dioxide in larger air ducts. Both products produce an analogue 0 to 10 V output and come with mounting hardware and simple mounting instructions. The Airestat T5000 wall-mounted carbon-dioxide transmitter has user-definable thresholds and three colours of LED to indicate carbon-dioxide concentration. The technology is based on the absorption of light in a gold-plated reflective light pipe or waveguide diffusion gas chamber. A gas-permeable Teflon filter prevents particles and water contaminating the sensor. Light is absorbed in proportion to carbon-dioxide concentration, and the remaining light is measured and converted into an analogue signal. The automatic calibration ensures self correction of drift to better than ±20 ppm per year. The system requires virtually no maintenance and typically has a life of more than 10 years.
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