Prudent practices for the design and installation of heat‐producing devices near wood materials

Abstract

SUMMARYThe conditions required to cause ignition of solid wood materials under short-term heating are examined, and it is found that the appropriate ignition temperature applicable under these conditions is 2508C. It is then shown that ignition requirements are different if long-term heating is involved and that ignition can occur at exposure temperatures much lower than the ignition temperature pertinent to short-term heating. It is shown that hot surfaces of 778C or higher, if located for a long duration next to a wood member are liable to lead to its ignition in a self-heating mode. Recommendation is made that prudent practices for design or installation must also involve a suitable safety factor.

Study of Radiant Smoldering Ignition of Plywood Subjected to Prolonged Heating Using the Cone Calorimeter, TGA, and DSC

“…Using detailed in-depth temperature measurements they showed that at radiant fluxes near the critical heat flux for smoldering ignition (7.5 kW/m 2 ), ignition occurs at depth within the charred portion of the wood sample. This contrasts with the interpretations of Boonmee and Quintiere [7,8] of smoldering ignition as a surface phenomenon and contrasts with the views of Babrauskas et al [3] that self-heating is not involved in short term (minutes to hours) heating to ignition of wood.…”

“…In a recent paper Babrauskas, Gray and Janssens [3] reviewed the old literature and anecdotal fire incidents and concluded that prolonged heating can reduce the ignition temperature of wood. No laboratory work was included in investigation.…”

Ignition: A Century of Research and an Assessment of Our Current Status

“…In addition, the ignition of wood is complicated since, not only can it ignite in either flaming or glowing mode due to short-term, external heating, but it is also a material susceptible to self-heating. The latter mode of ignition [22] can be encountered when a device such as a hot pipe provides long-term, low-temperature 1 heating.…”

“…The chemistry of drying oils is quite complex and a treatment based on F-K theory and currently available laboratory data does not capture the trends, since such an exercise predicts that roughly a 300-mm cube of material would be needed in a room-temperature environment, whereas a 25 g quantity has been empirically shown to suffice [1]. Another category of practical fires are the ones originating in wood members that have been heated for months or years by a steam pipe or similar hot object [22]. The process involves selfheating of wood, but, again, the simplified theory does not apply.…”