I bet there is a temperature between 300F and 590F where the volatile components of the oil are becoming significantly vaporized as to be highly susceptible to ignition from another source, like say the flame of the fryer itself (in a restaurant) or, maybe even so far as, a spark from a pump?
I don't use elements anywhere anymore, my process is heated with a boiler that directly heats the circulating oil or bio, I can set the temp anywhere from 100F to 200F, never anywhere near the ignition point of anything, the problem with elements is that left dry they get red hot, probably 800-1000 degrees before they burn out, I'm dealing with 300 gallons of oil, 55 gallons of methanol, that is just not compatible with electric elements.
That's a good description of the "flash point" test. At some point the vapors will sustain combustion, if there's an ignition source. As fabricator points out, an electric heating element becomes just such an ignition source as soon as it is uncovered.
A highlimit of 220 to 250F should be plenty high enough for any processor including one incorporating demething.
I bet the standard water heater highlimit is around there anyways...
Good info guys!
Simple schematic for a pump and heater control with a high limit
Sensor for the biodiesel/glycerin layer
Below is a list of the flash point and Auto ignition temperature of some common vegetable oils
Oil.........Flash Point.....Auto ignition
Well, it's more like the greatest majority of flame fests on this forum were started by the possibility of igniting methanol fumes.
From my discussion with two different fire marshals, they think the biggest cause of fires in homebrew is spontaneous combustion. I'd agree, with overheating the oil being the second biggest.
Those are some good numbers on flash point and auto ignition.
That is interesting information. For two different fire marshals to have personal statistics about what they think is the biggest cause of fires in home-brewing that would mean they both have attended home fires caused by making biodiesel. You do not often hear about fire departments attending biodiesel fires. I wonder if a lot of biodiesel home fires go unreported.
It's not that they have personally responded to a lot of homebrew fires. They have a political need to be knowledgeable about them. I assume they were calling the investigators of fires in other areas. They both mostly discussed fires outside their areas.
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