Torch Coolants FAQs
Answers to the practical questions buyers ask about coolant for water-cooled welding torches, plasma torches and their coolers.
Why can't I just use tap water in a water-cooled torch?
Tap water conducts electricity, and when current passes through it in a torch circuit it drives a corrosion reaction. Metals such as brass can dissolve and the particles can clog the torch, pump and cooler. Tap water also has no frost protection, so it can burst parts if the equipment is stored or moved in the cold.
Use a coolant made for torch cooling systems, and follow the torch and cooler manuals for the type to use.
What does 'low conductivity' mean on a torch coolant?
Conductivity is how easily the liquid carries an electric current, usually quoted in microsiemens per centimetre. Dissolved salts raise it, which is why tap water is poor. Purpose-made torch coolants are formulated to stay very low, and the figure rises as the coolant ages and picks up metal and dirt.
This matters most on plasma torches, where the head carries high voltage. A coolant that is too conductive can cause hard starting and damage to the torch. The acceptable level depends on the maker and the process, so check your manual.
Can I top up with water or dilute a ready-mixed coolant?
Not normally. A ready-mixed coolant is balanced for its frost protection and corrosion inhibitors, and adding water weakens both, which risks freezing and damage in cold conditions. Some makers sell concentrate that you mix yourself, so check the label to see which type you have.
If you must top up in an emergency, distilled or de-ionised water is far better than tap water, but treat it as a short-term fix and put the correct mix back in as soon as you can. Do not mix concentrate by guesswork; follow the ratio on the product label.
How can I tell if my torch coolant has gone off?
Look at the coolant and the cooler. Brown or cloudy liquid, suspended particles or sediment, algae growth, a pump that struggles or runs hot, and falling flow are all signs it needs attention. A conductivity meter gives a clearer answer, because coolant can look clean while its conductivity has already risen.
When you change it, drain the system, flush out debris, check or replace any filter, and refill with the correct coolant. A yearly change is not always often enough on heavily used equipment.