North Texas Homebrewers Association

Sadly, my Blichmann chiller went out while we were on vacation. I think it is the PTC relay/overload protector, but not sure until I can replace it. I ordered a new one and transferred the old glycol over. It has never been changed out since I got it a few years ago and I have only added a little water once presumable due to a little bit of evaporation. It got me to wondering about breakdown of glycol over time and concentration to gravity. The information I find on the web is very confusing about glycol concentration to gravity reading, so I'm wondering if anyone knows what 35% glycol to water dilution should render in specific gravity/brix? Also, I find very little about propylene glycol breakdown over time. Jimmy, I know you have some insights. Can you share what you know? Anyone else know anything about this? I don't want to even start my new chiller without knowing my fluid is within the recommended parameters.

I found this link in the past that gives SG to percentage by volume and weight: http://www.ppe.com/pdf/SpecificGravity.pdf

I was unaware of Propylene Glycol deterioration until Wayne said his glycol was pink with something growing in it. I now set my chiller to 50F when not in use instead of turning the unit off.

I needed to add a gallon of glycol to my chiller so I just did a 80/20 mix by volume. I have not tried to use SG to measure it. The chart above looks reasonable.

I do remember when I ordered my glycol there was an option for "inhibited" glycol but it seems to be for high temperature applications. I bought 5 gallons of the plain Propylene Glycol.

Here is the link at Duda Diesel: http://dudadiesel.com/search.php?query=propylene+glycol

A couple of thoughts:
1. The 80/20 percentage or whatever percentage you want to use is in mass not volume. I realize I did that wrong now. Not a big difference by the chart.
2. You could make a some mix of glycol water at the percentage you want and measure the gravity for future reference.

Thanks, Jimmy. This helps clarify. The manual only says: " add a mixture of 35% glycol and 65% distilled water." So, obviously that's a 35% glycol solution. I just measured the SG and it shows 1.046-1.048. Unfortunately, that does not correspond to a 35% solution. I have reached out to Blichmann for clarification as well. I did not have anything pink in the fluid, but there was some cloudy opaque stuff floating in it which I filtered out in the transfer. I also read something about bacteria or fungus essentially fermenting the glycol solution and reducing the percentage and acidifying the fluid. In a closed system, this could cause degradation of internal components. I do not know what truth there is to this.

Updates: The chart you provided Jimmy does correspond to a 35% by volume mix of glycol to water. I don't know how I got to 1.046, but will be adjusting by diluting with water in the new chiller.

Regarding the old chiller, as of this morning it is running again thanks to a rebuild of the start relay. This little device is part of the PTC start relay and overload protector on the side of the compressor. It contains some sort of metallic-ceramic disk(pic below) that can fail and break. This is exactly what happened. I could never find an exact replacement for the part(pic below), so I purchased a generic relay and pulled the disk out of that. All I had to do was make sure it was rated at 4.7 ohms. I also replaced the start capacitor even though the old one tests as good.

Lastly, I now have a working Blichmann glycol chiller for sale if anyone is interested. I sort of panicked since I'm hosting the brew day in September, plus they gave me a 20% discount on a new one for my troubles