EASE OF SAMPLING
Sample flows into the analyzer through the front panel fitting, and vents out through an exhaust port on the back panel. The exhaust port can also be equipped with a connectible luer fit connection, should you wish to keep your system closed. The recommended flow rate is 50 cc/min, although the analyzer can accept 10 to 1000 cc/min without adversely affecting the response time or readings.
The sensor operates at atmospheric pressure, and a flow bypass in the internal plumbing arrangement allows for excess pressure to vent. This allows for higher acceptable flow rates, without affecting the accuracy of your measurements.
NO SOURCE OF FLOW OR POSITIVE PRESSURE? NO PROBLEM.
For systems where a source of sample flow (or positive pressure) is not available, the Model 902P can be equipped with an optional internal miniature diaphragm pump with an on-off switch on the front panel. This pump draws about 5 cc/second from your chamber, experiment, room, or system.
The pump is electronically controlled to operate only when sampling, and can be adjusted to run for 2-12 seconds per button press. Furthermore, if you equip the analyzer with the pump, you can still introduce sample directly into the inlet fitting without pressurizing the analyzer or affecting your readings.
The pump is electronically timed to draw in the amount of sample required for the analysis, and then turns itself off after the pre-set sampling time (2 to 12 seconds). Advanced optional pump controls include two mode pump switch (for continuous pump or timed operation), cycling pump (set to run for x seconds on, x seconds off), or concentration activated pump (pump turns on when O2 or CO2 goes above or below preset limit).
INTERNAL, USER-REPLACEABLE MOISTURE TRAP FILTER
While the sample introduced should be clean and dry (non-condensing), should moisture enter the analyzer, the Model 902P is equipped with an internal moisture trap filter. This provides a last barrier of protection, and is user-replaceable (we provide spares).
ABOUT THE CO2 SENSOR
The Model 902P uses a solid-state infrared CO2 sensor which has no moving parts, a compact optical cell, and microprocessor-based calibration factors using a 6th order polynomial equation to linearize the full range measurement up to 100%. Infrared CO2 measurements are inherently non-linear, especially over a high range of concentrations. The math algorithm used in the 902P yields more accurate results over a much wider range of concentrations than other methods. The expected life of the CO2 sensor is theoretically unlimited, as it contains no moving parts.
The Model 902P CO2 sensor combines cutting edge 32-bit digital signal processing with the solid reliability, compact size and state of the art microprocessor technology that makes this full-featured CO2 measurement system less complex and more robust than other instrumentation.
ABOUT THE O2 SENSOR
The Model 902P uses a long-life heavy duty electrochemical O2 sensor, with an expected lifetime of 5 years. Other electrochemical O2 sensors have an expected life of 1-2 years.
Both the CO2 and O2 sensors are unaffected by high levels of background gases such as nitrogen. The O2 sensor is unaffected by high levels of CO2, and vice versa.
ABOUT THE MICROPROCESSOR/ELECTRONICS
Micro-processor based electronics provide sensor signal processing, battery charging, pump timing and on/off control for high accuracy and reliability with minimal component use and reduced size and cost.
ABOUT THE OPTIONAL BATTERY
With its low power requirement, the Model 902P can be operated with an optional battery for those applications where AC power is not readily available, or for convenience if spot checking samples at different locations. A totally sealed, long-life internal 12 Vdc battery accepts a full or partial charging cycle and will operate the unit for up to 8 hours. The charger module plugs into a standard 110-240V outlet for charging or continuous operation. Alternatively, the unit can be powered from an external 12-24 Vdc source.
ABOUT THE WARRANTY
The Model 902P is backed it up with a two year warranty, twice the industry standard. The advanced design allows an output requiring less frequent calibration. It provides a stable, drift-free linearized voltage or current output that is much less susceptible to external electro-magnetic interference than conventional analog electronics.