NAP-78SU is a gas sensor for monitoring incomplete combustion. NAP-78SU can be installed in a flue duct for direct monitoring on stoking equipment. Usually this type of sensor has individual temperature dependency to require an individual compensation circuit, but this has been the cause of the high cost of such sensors to eventually impede the popularization, however, NAP-78SU’s temperature dependency can be compensated by a simple circuit and does not need an individual circuit.


NAP-78SU's Structure

Gas sensitivity characteristics

Gas & Concentration Output voltage
Output in clean air +30±3 mV
CO 1,000 ppm + H2 500 ppm 5 - 7mV (Normal Temp.), 4 - 5mV (200°C)
Temperature dependency at Zero point Zero point variation ±1.0mV or less between normal temperature and 200°C
Gas sensitivity characteristics Recommended measuring circuit


Items Ratings
Supply voltage DC 2.0±0.1V
AC 2.0±0.1V(r.m.s. 50-60Hz)
Heat cleaning voltage DC 2.75±0.1V
AC 2.75±0.1V(r.m.s. 50-60Hz)
Heat cleaning cycles 30-60sec. only upon switch-on
O2 concentration 1 - 21 %
CO/H2 1/1 - 1/4
Current (2.0V supplied) DC 140 - 160mA
AC 140 - 160mA(r.m.s. 50-60Hz)
Ambient Temperature In operation 0 - +200°C
In storage -10 - +50°C
Ambient humidity In operation 95%RH or less
In storage 99%RH or less(without dew condensation)