Are you aware that glycols are used in many industrial plants? In food plants their main applications include secondary cooling and heating, deicing, defrosting, dehumidifying, and winterizing pipes. It can also be used in process heat exchange units and in enclosed cooling loop operations.
Differences between Propylene and Ethylene Glycol: There are two major types of glycols that are used in the industry for these applications, propylene glycol and ethylene glycol. There major differences between propylene and ethylene glycols are viscosity and toxicity. Ethylene glycols are less viscous and therefore generally provide superior heat transfer efficiency and better low temperature performance. However, in applications where toxicity is a concern such as food plants, propylene glycol fluids are used because of their low acute oral toxicity vs. the moderate acute oral toxicity of ethylene glycols. Examples include applications where contact with drinking water is possible, food processing applications where accidental contact with food or beverage products could occur, and where propylene glycol use are mandated by law.
Freeze and Burst Protection: During the winter times, maintenance and engineering departments are worried about the low temperatures and system integrity. Burst protection is sufficient if the system will remain dormant when the temperature is below the freezing point of the solution. Freeze protection is required in systems where fluid must be pumped at the lowest anticipated temperature. See the freeze point vs. glycol concentration chart below.
Inhibitors: Corrosion control can be a major concern when glycols are diluted to obtain maximum freeze protection. There are food grade corrosion inhibitors that are incorporated and blended with the propylene glycol to prevent metal corrosion. For this typically ASTM D4627-92 "Iron Chip Corrosion for Water-Dilutable Metalworking Fluids" is used. See the corrosion test particle results below.
Corrosion Protection at Varying Concentrations:
Freeze Point vs. Glycol Concentration
Reach out to the RITE team™ for more information on glycols for freeze protection and corrosion control.
The RITE Team™
By The RITE Team™
Hydrite’s RITE Team™ is a group of experienced professionals tasked to enhance the technical support in the field to introduce innovative solutions that help address critical issues in the food industry.