[PSUBS-MAILIST] O2 & CO2 sensors

["Cliff Redus" <dr_redus@devtex.net>]

Alec, follow-up on CO2 sensor.   See
http://www.enmet.com/manuals/CO2AirSenseManual.pdf  for a CO2
sensor/transmitter.  This unit comes in two flavors, 0-2000 ppm and 0-5000
ppm.  Both $695 (J. S. Systems, Houston TX 713-690-1300).  Units have LED
display of CO2 partial pressure in ppm and also either a 4-20mA or 0-10VDC
output signal that is proportional to CO2 partial pressure.  Normal air CO2
level at one atm. is 0.0314% ( Burgess Jennings, "Environmental Engineering,
Analysis and Practice", pg 85 ) or 314 ppm.  ABS rules say CO2 level must
not exceed 0.5% or 5000 ppm.  I am leaning towards the 0-2000 ppm sensor
because of accuracy (0- 2000 ppm unit accuracy is +/- 75ppm, while the
0-5000 ppm unit is +/- 250 ppm.).

Still looking for a lower cost CO2 sensor but this is a starting point.

Cliff