[Amps] oil cooling..again

[Jim Thomson]

It was mentioned about getting oil too hot..and too close to its flash point etc.  If you look at Globar resistors, type SP, that are used in dummy loads,
you will see that when they are maxed out, they are running at 350 deg C !    That’s  a whopping 662 deg F !   The resistor inside the heath dummy load
is rated at 90w CCS..in air.   Its only .750 inch diam x 5 inchs  long.   So in air, with 90 watts applied CCS,   its surface temp is 662 deg F.    Now stuff it into
one us gallon of xfmr oil, and heath rates it at 200 W  CCS.    And more if duty cycle is way down.  How many of us have stuffed 1-2 kw into it for a few seconds,
or  even longer ?    Or pulse tuned into a heath dummy load. 

The oil in these oil cooled dummy loads can get extremely hot..... with violent boiling of the oil.    I used 4 x 200 ohm globars in parallel for a 50 ohm load.
Each resistor is 1 inch diam x 12 inchs  long.   Each is rated at 225 watts CCS in air.   So  1100 watts ccs in total..in air.   Each resistor is placed inside an AL tube.
All 4 x 2.875 OD x sched 40 al tubes welded together.  Then the entire mess goes into 7.5 us gallons of xfmr oil.... suspended from the lid.   Sorta like
a heath dummy load..on steroids.  

Point is, with the correct xfmr oil used,  the oil will not burst into flames.   With the correct flow rate into a GS35B,  oil temps should not be an issue,
provided that  a correct size rad is used, along with an expansion tank...aka  de-gas bottle, plus pump for the job, etc, etc. 

Jim  VE7RF