[Stepan]

Hello. I visited a plant where they use 50/50 Glycol/water coolant to control temperature of the polymer extrusion lines. Temperature goes as high as 70 C and as low as -30C. They have intensive corrosion. The coolant is virtually red with heavy precipitate of rust in overflow tanks. I was asked to give my recommendations for to control the corrosion. They use some inhibitors, but overall control needs improvement.

The questions are: if they reduce contact of the coolant with air, would it slow down the corrosion?; is there any inhibitor which would work for steel at pH 6-7?

Thank you

[Enthalpy]

That wasn't your question, but...

A common hydraulic fluid is polyglycol+water+additives (for cylinders and so on). One commercial name is Hydrolub, various viscosities exist. It is not water+glycol, it is not a coolant.

But it stays liquid between -30°C and +70°C, and it has all additives to work in hydraulic circuitry without corrosion. Good lubricant of course. Extensive documentation, including thermal data. Probably already used by the polymer extrusion line for the hydraulic circuit.

Maybe you can misuse it as a coolant?

Or you could search for the anticorrosion additives used with polyglycol+water, though this one is an ether with few alcohol groups.

[Stepan]

That wasn't your question, but...

A common hydraulic fluid is polyglycol+water+additives (for cylinders and so on). One commercial name is Hydrolub, various viscosities exist. It is not water+glycol, it is not a coolant.

But it stays liquid between -30°C and +70°C, and it has all additives to work in hydraulic circuitry without corrosion. Good lubricant of course. Extensive documentation, including thermal data. Probably already used by the polymer extrusion line for the hydraulic circuit.

Maybe you can misuse it as a coolant?

Or you could search for the anticorrosion additives used with polyglycol+water, though this one is an ether with few alcohol groups.

Sounds good, but I need 4000 galons  , I do not think that it is safe to run a "trial" of this scale.