Friday, July 13, 2018

[qvhaepbp] Oven cooling fans and oven fires

Food in your oven has caught fire.  In the olden days, the right thing to do was to turn the oven off and wait: with the oven door shut, the fire will be deprived of oxygen and burn itself out.

Nowadays, modern ovens often have oven cooling fans to protect their electronics; these fans run even when the oven is switched off.  Such a fan continuously pumps oxygen into a fire in the oven and pumps smoke out of the oven into the living area.  Both of these seem very problematic: you've created a fireplace.

Ideally, the air pathway of the oven cooling fan cooling its electronics is isolated from the cooking chamber of the oven.  We have observed this to be false in practice: when the fan turned on, the flames of the food on fire grew and smoke poured out of the cooling fan vent.

Instructions on dealing with oven fires give contradictory instructions: do not open the oven door because of danger that the fire will flash and burn you due to the sudden influx of air, and use a fire extinguisher.  However, a fire extinguisher cannot be used on burning food inside the oven without opening the door.  I suspect the contradiction is supposed to be resolved as follows: if the fire minor, it will burn itself out with the oven switched off and the door kept closed.  If the fire is major, it is worth the risk of harm to oneself in opening the door and using a fire extinguisher on it.  This is a bad situation because a typical person who only rarely deals with oven fires cannot accurately judge minor versus major and cannot accurately judge the risk/benefit tradeoff of opening the door.  With an oven-cooling fan possibly feeding a self-sustaining fire inside the oven, this decision becomes even more difficult.

One could pull the circuit breaker, shutting off the oven cooling fan.  Again, this is a difficult decision: is the decreased airflow to the oven fire and consequent possible more rapid extinguishing through oxygen deprivation worth the increased chance of damage to the oven electronics, the latter likely requiring very expensive oven repair or replacement?

No comments :