Validation of a Fine Water Mist Fire Extinguisher (T0010-P) (FWM PFE)

Developing and refining a portable fire extinguisher (PFE) for use in microgravity environments. This technology uses fine water mist (FWM) to effectively and efficiently extinguish fires that are representative of spacecraft hazards. 

In this experiment, droplet size distribution is determined using a Malvern Spraytec instrument located inside a sealed enclosure in a first experiment.  In a second experiment, droplet transport around obstructions is measured via infrared light scattering in a remote region of the same obstructed enclosure.

The three primary objectives of the proposed experiments are to: (1) demonstrate that the water atomization process taking place inside the PFE and the subsequently generated water mist plume are not measurably affected under reduced gravity conditions, (2) demonstrate that water mist droplets transport through a tortuous or greatly obstructed path is more efficient in weightlessness as droplets will not tend to settle, and finally (3) measure the light obscuration due to a water mist plume dispersing in an open enclosure as this was identified as a potential concern in a manned vehicle.

Two separate experiments using essentially the same setup are proposed. The two experiments would be performed on different days to allow for adjustment of the apparatus and refilling of the prototype extinguishers. In the first experiment, ADA’s PFE FWM will be discharged inside an enclosure across the path a laser beam of a Malvern Spraytec instrument in order to measure droplet size distribution (DSD) upon discharge. ADA has an extensive database of measurements made in the laboratory with the Malvern instrument to which the flight measurements will be compared. Light obscuration due to the mist dispersion in the back section of the enclosure will also be measured. In the second experiment baffles will be installed inside the enclosure, spanning most of its length to form a space representative of experiment racks used on the ISS. The prototype PFE will be discharged into this space, and the migration of mist throughout the obstructed volume will be characterized. In this experiment, we will as above discharge the PFE, then measure the obscuration due to water mist in two locations downstream of the obstructing baffles for the remaining near-zero-g time.