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Fire Hazards of Dry Versus Watered Christmas Trees

Research Overview

These experiments were designed to examine the difference in fire hazard between a dry Christmas tree and a watered Christmas tree for fire safety awareness. One dry tree (no water after harvesting) and one watered tree was tested with no replicates. The test specimens were approximately 2.1 m (7 ft.) tall Douglas fir trees cut fresh from a local Maryland tree farm approximately four weeks prior to testing. The watered tree was placed in a bucket of water within 3 hours of being harvested and a fresh cut was made approximately 50 mm (2 in.) from the base of the trunk prior to placement in the water. Both the dry tree and watered tree were stored indoors until the day of the test. For fire testing, each tree was placed in a mockup of a corner of a living room constructed to provide background for video recording and not to replicate a specific or typical living room. The ignition source was a book of matches with the match heads wrapped with a thin nickel-chromium wire that heats, igniting the matchbook, when electricity is applied. Three attempts were made to ignite the watered tree during which the ignition source and position of fuel adjacent to the ignition source were varied, however, no sustained ignition of the tree was achieved. For the dry tree, ignition of the tree was achieved on the first attempt and a peak heat release rate of 7362 kW was reached 31 s after ignition.

Experiment Name Plot of Heat Release Rate Ignition Photo Date/Time Sort descending Specimen Fuel Type Test Duration (min) Total Heat Released (MJ) Peak HRR (kW)
WateredTree3
Plot of Fire Heat Release Rate with event markers. Uncertainty bar shown at peak value.
Ignition
watered pine tree, upholstered chair and shelf in room corner Cellulose, Plastic
4.05
below detection limit
6.7
Dry_Pine_Tree
Plot of Fire Heat Release Rate with event markers. Uncertainty bar shown at peak value.
Ignition
dry pine tree, upholstered chair and shelf in room corner Cellulose, Plastic
16.55
938
7,362

Bryant, R. and Bundy, M. The NIST 20 MW Calorimetry Measurement System for Large-Fire Research, Technical Note (NIST TN) 2077, 2019
https://doi.org/10.6028/NIST.TN.2077

NIST Fire Calorimetry Database (FCD)
https://doi.org/10.18434/mds2-2314

Last Updated April 12, 2021