Fires from Blankets Warmed in Microwave Ovens
Hazard [Health Devices Jun 1989;18(6):234-5]
A member hospital reported that a blanket warmed in a microwave oven burst
into flames when it was passed into a hyperbaric oxygen chamber. The hospital suspects
that the blanket was smoldering within its folds when it was placed in the chamber. Our
tests have confirmed that this is a likely scenario. We know of at least one other case
where a blanket ignited while being heated in a microwave oven.
A blanket inside the oven may warm because of absorption of microwaves by
the blanket material, but the effect is likely to vary, depending on, for example, the
material type and moisture content. However, microwave use may result in severe hot spots
in the blanket and ignition due, in part, to uneven heating patterns within the oven.
Unlike items heated within a conventional oven or warming cabinet, items heated in
microwave ovens do not equilibrate to a set chamber temperature. Rather, they continue to
heat as long as they are exposed to the microwave energy. Hot spots from microwave heating
can cause smoldering and burning of the blanket while it is in the oven. Once removed from
the oven, a blanket that is smoldering within its folds may burst into flames if exposed
to oxygen or if permitted to smolder long enough.
- Do not use microwave ovens for warming any blankets. Such use can result in fire, which
could cause injury or death.
- Use commercially available hospital blanket warming
cabinets. Such cabinets are warmed by either electric heaters or steam and
do not present a blanket ignition hazard, even if the warmed blanket is
subsequently exposed to an open oxygen source or placed in a hyperbaric
- Blankets [10-415]
- Cabinets, Warming [10-540]
- Warmers, Blanket [10-414]
Cause of Device-Related Incident
User errors: Abuse of device; Incorrect clinical use
Mechanism of Injury or Death