The Fire Atmospheric Sampling System (FASS) package samples smoke from the scene of a wild or prescribed fire and stores it in canisters for later analysis.

The FASS is deployed directly in the path of the fire to sample emissions. It includes a tower of adjustable height and two sample instrument packages- one for measuring real time continuous gas concentrations and another to collect canister samples.

PRINCIPLE INVESTIGATOR

Bryce Nordgren, Physical Scientist

FUNCTION AND OBJECTIVES

The tower includes a multi-section pole through which tubing is fed from a sampling head at the top. The head contains inlets for gas and canister sampling, anemometers to measure wind speed, teflon filters to measure fine particulate concentration, and a thermocouple for temperature. There are two sampling packages at the base of the tower, protected by fire shelters. The main package contains pumps that draw the smoke through tubing in the tower from the sample inlets. The smoke passes through CO and CO ₂ sensors that continually measure concentrations during flaming, intermediate, and smoldering phases of the fire. The other package contains a pump- flow control system and four canisters to collect smoke samples for laboratory analysis.

METHODS

Three or four FASS systems are set up on the site ahead of the wildfire or prior to a prescribed or experiment fire. The towers are arranged in a configuration that provides a good chance of sampling representative emissions of the fuels as they burn on the site.The height of the towers is based on the predicted flame height and fire intensity, with sufficient height as to not damage the sample head and effectively capture the smoke as it rises.The sample packages are programmed with a trigger level of CO₂ to initiate the sampling process.Then they are covered with fire shelters, ready to sample. The package first takes a background air sample, and begins monitoring the CO ₂ level. As the fire approaches, the CO ₂ concentration rises to the trigger level and the sampling program begins.