[TheForge] oil temps (one more time)

[Steve Bloom]

At 08:53 PM 11/17/2010, Peter wrote:
>[snip]Inferring that when an oil begins to smoke, it has reached a designated
>temperature, depending on type. These temps are within the tempering range.
>A guy who worked custom auto springs said the old guys would harden,
>then reheat till the oil flashed, and repeat several times.

I'm in the early stages of building an oil tempering bath for 
Japanese sword work. A screw-in 110V water heater element screws into 
a 1" pipe fitting = so, combine that with an appropriate pipe, a 
variac and a candy thermometer, and the basic idea of an electrically 
heated, adjustable tempering bath looks feasible. As part of the 
process, I collected the data cited below-- a table of flash temp and 
costs for common oils. The problem is that there is a reason it's 
called "flash" temp, i.e., "Flash point is the lowest temperature at 
which a liquid can form an ignitable mixture" --so, get it that hot 
and things might get real interesting.  Peanut oil is selling here in 
Florida at $30/ 3 gallons, so that definitely looks like the sweet 
spot.  400F pulls 1065 from 62 Rockwell C to 57, so there is promise here.

steve

        Oil      Temp (F)        rank    Price   rank
Safflower       509       1     $50.80  11
Sunflower       475       2     $61.52  13
Soybean 466       3     $23.33     6
Canola  460       4     $22.42     4
Corn    457       5     $18.70     2
Peanut  448       6     $28.67  10
Synthetic Motor 446       7     $22.55     5
Hydraulic Oil   430       8     $25.00     8
Natural Motor   420       9     $13.16     1
Sesame  419     10      $79.78  14
Olive   374     11      $26.28     9
Lards   361     12      $19.75     3
Dexron ATF      356     13      $23.96     7
Brownell's Tough        354     14      $57.99  12
  Quench oil