Greisinger carbon monoxide transmitter gt1 co greisinger gt1 co p the greisinger gt1 co is a high quality and t 220 v certified co transmitter incl measuring cell for detection of carbon monoxide in underground and parking garages boiler plants heating systems garages as well as in ambient air p p the 4 20ma output is intended to be connected to suitable displays or apparatus the gas is measured at the sensor inlet sideways blue assembly position inlet pointing downwards the