Water-Vapor Analyzer

The Forest Products Laboratory (FPL) seeks a robust measurement systemwhich can capture the rapidly changing water vapor levels which accompanycombustion events. The system must provide a voltage output at 4 Hz or faster, which reflects the water vapor concentration (or vapor pressure) in a localized region experiencing the high temperatures and dust (soot) typical of combustion. We want this device to be placed in situ, not extract an air sample for analysis after removal and filtration such as typically occurs with FTIR systems. The primary requirement is speed of response to reflect rapidly changing water vapor levels. The secondary requirement for in situ placement
reflects a desire for minimal disruption of the natural air flows induced during combustion. For example, such a device could be placed near a leaf which is subjected to a high heat flux and eventually ignites causing a rapid rise in air temperature and water content near the fire, inducing an upward airflow past the leaf.

The system is expected to work in a laboratory environment, so only the probe needs to be able to endure placement near a fire. Beyond the leaf example above, another possible deployment of the system would be in the combustion exhaust stream of fire research instruments like the cone calorimeter. In that application the temperature rises up to 200 °C with dust levels (from soot) typically near 100 mg/m3 but with a high of 500. A variety of other gases, including combustion products, will also be in the air with the water vapor, including CO2 (up to 10%), CO (up to 2%), O2 (from 0 to 21%), with many trace gases (ppm), some of which could be corrosive and/or toxic.

The system must be able to run for a minimum of 6 hours before requiring cleaning or maintenance.

We are agnostic about the physical mechanisms used to measure water
vapor. The commercially available TDLAS systems we are familiar with are too slow, and the common capacitive RH sensors are both too slow and not robust to high temperature and soot.

Vendors that have an instrument that meets the Government's needs
identified above should respond to this Sources Sought Notice by emailing the Contracting Offier listed on this announcement. Please include specific information regarding the performance specs and requirements of the equipment available or a proposal for research and development to create a prototype instrument.