Types of Glycol for Heat Transfer: Propylene Glycol vs. Ethylene Glycol
Glycol-based heat transfer fluids are commonly used to manage system temperatures, provide freeze protection, and help protect components from corrosion. The type of glycol, corrosion inhibitor package, system materials, operating conditions, and application all play a role in selecting the appropriate fluid. Understanding the differences between propylene glycol, ethylene glycol, and specialized glycol formulations can help you determine which heat transfer fluid is best suited for your system.
Propylene Glycol vs. Ethylene Glycol
The two primary types used in heat transfer systems are propylene glycol (PG) and ethylene glycol (EG).
Propylene glycol is commonly selected when low toxicity is an important consideration. PG-based fluids are used across commercial HVAC, food and beverage, pharmaceutical, geothermal, data center, and industrial heating and cooling.
Ethylene glycol is also widely used for industrial heat transfer and freeze protection. It is generally selected for systems where elevated toxicity characteristics are not a concern, given ethylene glycol products are considered hazardous.
Dow offers heat transfer fluids based on both PG and EG, with different formulations designed for specific applications.
Food Grade vs. Industrial Propylene Glycol
One important distinction is that propylene glycol does not automatically mean food grade.
DOWFROST™ Heat Transfer Fluid contains 96% food-grade propylene glycol along with food-grade corrosion inhibitors. It is made entirely from food-grade raw materials conforming to FDA CFR 21 and NSF guidelines and is acceptable as a heat transfer fluid where incidental food contact is possible. This makes DOWFROST™ particularly well suited for applications such as:
- Food and beverage processing
- Refrigeration and freezing
- Geothermal systems
- Secondary heat transfer loops
DOWFROST™ HD Heat Transfer Fluid is also propylene glycol-based, but it contains a specially designed package of industrial corrosion inhibitors. DOWFROST™ HD also has a broader recommended upper operating temperature than standard DOWFROST™, making system temperature another consideration when choosing between the two.
It is intended for demanding closed-loop heating and cooling applications, where food grade is not required, such as:
- HVAC and industrial systems
- Process heating and cooling
- Fire water sprinkler systems
- Thermal Energy Storage (TES)
When to Choose DOWFROST™ vs. DOWFROST™ HD
Because DOWFROST™ and DOWFROST™ HD are both propylene glycol-based, the intended application and operating conditions are important considerations when selecting between the two. Choose DOWFROST™ when incidental food contact is a concern or when a food-grade heat transfer fluid is required. Choose DOWFROST™ HD for closed-loop HVAC, process heating and cooling, and other industrial systems where a heavy-duty industrial corrosion inhibitor package is preferred.
Other Glycol Heat Transfer Fluids
Beyond DOWFROST™ and DOWFROST™ HD, specialized formulations are available for more specific system requirements.
DOWCAL™ 200 Heat Transfer Fluid is propylene glycol-based and provides improved corrosion protection, particularly for aluminum alloys. It is used in applications including:
- Residential HVAC/hydronic systems
- Process heating and cooling
- Heat recovery systems
- Floor heating
- Solar heating
- Snow melting systems
- Wind turbines
DOWFROST™ LC 25 Heat Transfer Fluid is a specialized propylene glycol-based fluid developed specifically for data center liquid cooling. Its customized inhibitor package is designed for direct-to-chip cooling systems with high surface-area copper components Applications include:
- Direct-to-chip liquid cooling
- Datacom Equipment Cooling Systems (DECS)
- Coolant Distribution Units (CDUs)
- Glycol Cooled Computer Room AC Units (CRAC)
- Pumped refrigerant and glycol loop heat exchangers
For applications where the lower toxicity characteristics of propylene glycol are not required, DOWTHERM™ SR-1 Heat Transfer Fluid provides an ethylene glycol-based option for industrial heating and cooling systems. It is formulated with 95.5% ethylene glycol and a specially designed 4.5% package of industrial corrosion inhibitors. It is manufactured with 100% virgin ethylene glycol and uses a heavy-duty inhibitor package designed to help protect system metals from corrosion and extend fluid life. It is commonly used in applications such as:
- Ice skating rinks
- FSRU (Floating Storage Regasification Unit)
- Temperature-sensitive material processing
- Deicing and defrosting systems
- Dehumidifying systems
Choosing the Right Glycol Heat Transfer Fluid
Selecting the right heat transfer fluid involves more than choosing between propylene glycol and ethylene glycol. Consider the system’s operating temperature, materials of construction, freeze protection requirements, corrosion protection needs, and whether incidental food contact is possible.
Even two propylene glycol-based fluids can be designed for very different environments. Looking beyond the glycol type and considering the complete formulation can help support reliable heat transfer and long-term system performance.
Lentus is a Master Distributor for Dow glycol-based heat transfer fluids, offering DOWFROST™, DOWFROST™ HD, DOWCAL™ 200, DOWFROST™ LC 25, DOWTHER™ SR-1, and other heat transfer solutions in multiple concentrations and package sizes.
Need help selecting which glycol heat transfer solution is right for your application? Contact Lentus to discuss your system requirements and find the appropriate Dow heat transfer fluid for your operation.
Call us at 270-765-2212 or email Orders@LentusLLC.com.
