Just like method #23 but with better cooling system. 

So I've made 3D printed sleeve to better cool the flask arm. 

Let's see if we get better results with it.

As I've turned on the pump water started to leak.

Yeah, 3D printed not good for pressure but coating with thin layer of epoxy glue will solve the problem 

Added a thin epoxy layer and leakage stopped. This time temperature was right not too high. Cooling temperature was above dew point. Still got low concentration of nitric acid. I don't know maybe it was humidity that kills the acid. 

I've started to think about how can I prevent humidity. At this point I we realized that this went way too far. I mean, I got an enclosure and fan and windows too look at. Water cooling system, pump bucket of water. I got stove and electric relay to control with Arduino temperature sensor. And PC to monitor. 

THAT'S NOT SIMPLE AT ALL! 

The previous ideas was easy just bit of potassium nitrate and drop of Sulfuric acid. And heater that's all, unfortunately it breaks bond wires. 

I will not continue this method as it becomes too complicated and not safe.