when you have a job that has a spec. for a certain glycol mixture,say 30%,does that mean it is 30% pure glycol and 70% water or 30% pure glycol and 70% inhibitors? we normally buy our glycol pre mixed and give the supplier this spec.
glycol and 70%water. Ideally it should be de-mineralized water if you buy 100% glycol and blend it at the jobsite. You can purchase DE water or rent a filter to use at the jobsite to filter your source water. For large jobs requiring hundreds of gallons of blend water it might make sense to treat the water at the site, or buy drums of pre-mixed glycol.
If a manufacturer of glycol knows how you are going to blend it they will inhibit it accordingly. So with a 30% glycol mix they would add more inhibitors, as one of the inhibitors job is to compensate for the blend water.
Inhibitors buffer the ph, lock up hardness, film providers, O2 scavangers, color, etc.