[Amps] Liquid Cooling Systems

[Tony King - W4ZT]

Many of the coolants that have been discussed in this thread require a 
pressurized system to work properly (like automotive systems).

There is an ethylene glycol based coolant that is used in welding 
systems which do not run pressurized. Most commercial coolants contain 
additives to reduce surface tension and also to prevent interaction with 
metallic components.  The coolant used for welding systems must 
withstand voltages much higher than we normally see in high power 
amplifiers during High Frequency start/run. They are used to cool 
welding torches in plasma, MIG and TIG machines and operate at very high 
temperatures.

For those that aren't familiar with HF start, modern TIG (Tungsten Inert 
Gas which used to be Heliarc) welders provide a high frequency high 
voltage arc to initiate the ionization of the argon shielding gas. It is 
this ionized argon which subsequently maintains the low voltage arc used 
to weld with. In conventional AC TIG welding the HF is run continuously 
to maintain the arc through the zero crossing in the AC voltage (used 
primarily for aluminum).  For the DC process, the HF high voltage is 
applied for a short period only at the beginning of the process.  Modern 
day inverter type welding machines will provide HF during the start 
process only for both DC and AC because the AC process is accomplished 
with square waves instead of sine wave AC.

Welding coolant is usually available for around $20 per gallon at your 
local welding supply. It is also an effective antifreeze to about -60F.

I don't have any experience using this coolant for cooling vacuum tubes 
but it stands to reason that it is a likely candidate.

73, Tony W4ZT