September 7, 2026 · VASTEC Chemical
Glycol Comparison Guide: Ethylene Glycol vs Propylene Glycol vs Diethylene Glycol
Glycols are among the most versatile chemical families in industrial applications. From antifreeze to polyester production, from gas dehydration to pharmaceutical formulations — the right glycol choice depends on your specific application requirements. This guide compares the four main glycols in VASTEC's portfolio to help you make an informed sourcing decision.
The Four Main Glycols at a Glance
| Property | MEG | DEG | TEG | PG |
|---|---|---|---|---|
| CAS Number | 107-21-1 | 111-46-6 | 112-49-2 | 57-55-6 |
| Molecular Formula | C₂H₆O₂ | C₄H₁₀O₃ | C₆H₁₄O₄ | C₃H₈O₂ |
| Molecular Weight | 62.07 | 106.12 | 150.17 | 76.09 |
| Boiling Point | 197°C | 245°C | 285°C | 188°C |
| Freezing Point | -12.9°C | -8.3°C | -7.2°C | -60°C |
| Viscosity (25°C) | 16.1 mPa·s | 35.7 mPa·s | 47.8 mPa·s | 42 mPa·s |
| Toxicity | High (toxic) | Moderate | Low | Low (GRAS) |
| UN Hazardous | No | No | No | No |
Mono Ethylene Glycol (MEG) — The Workhorse
CAS 107-21-1 · The world's highest-volume glycol with 30+ million tons annual production. MEG is the cost-effective choice for non-food applications where toxicity is not a concern.
Best Applications
- Antifreeze & coolant — Freeze protection to -37°C. The global standard for automotive cooling systems
- PET resin production — Reacts with PTA to produce PET chips for bottles, films, and packaging
- Polyester fiber — Staple fiber, filament yarn, and nonwoven production (99.9% fiber grade)
- Natural gas dehydration — Removing water from gas pipelines to prevent hydrate formation
- HVAC heat transfer — Chiller fluids and geothermal systems
Available grades: 99% industrial grade and 99.9% fiber/PET grade
Packaging: 230kg drums, 1000L IBC totes, flexitank (20,000 kg)
Diethylene Glycol (DEG) — The Intermediate
CAS 111-46-6 · A co-product of MEG production with a higher boiling point and different solvency characteristics. DEG serves as both a solvent and a chemical intermediate.
Best Applications
- Unsaturated polyester resins (UPR) — Reacts with maleic/fumaric acid and styrene to produce fiberglass-reinforced plastics
- Plasticizer production — Raw material for diethyl phthalate and other plasticizers
- Humectant — Moisture retention in tobacco, inks, and adhesives
- Natural gas dehydration — Higher boiling point than MEG makes DEG suitable for high-temperature gas streams
- Polyurethane coatings — Chain extender in two-component PU systems
Key difference from MEG: DEG has lower toxicity, higher boiling point, and better solvency for polar organic compounds
Triethylene Glycol (TEG) — The Specialist
CAS 112-49-2 · The highest-boiling glycol in common use. TEG's low vapor pressure and excellent hygroscopic properties make it ideal for gas processing and air treatment.
Best Applications
- Natural gas dehydration (primary) — The industry standard for deep dewpoint depression in gas processing plants
- Air sanitizing & disinfection — TEG-based systems sanitize air in hospitals, clean rooms, and food processing facilities
- Cellulose film plasticizer — Improves flexibility in regenerated cellulose films
- Specialty solvents — High-boiling solvent for dye manufacturing and chemical synthesis
Key difference: TEG has the lowest vapor pressure and highest boiling point — critical for gas dehydration where minimizing glycol losses is essential
Propylene Glycol (PG) — The Safe Choice
CAS 57-55-6 · The only glycol generally recognized as safe (GRAS) by the FDA. PG's low toxicity makes it the default choice for food, pharmaceutical, and cosmetic applications.
Best Applications
- Food & beverage — Humectant, solvent for flavorings, and antifreeze in food-grade applications
- Pharmaceutical formulations — Solvent and co-solvent in oral, topical, and injectable preparations (USP grade)
- Personal care — Moisturizer, solvent, and viscosity modifier in cosmetics
- Industrial antifreeze — Non-toxic alternative to MEG for food processing equipment and potable water systems
- Unsaturated polyester resins — Premium-grade UPR for marine and food-contact applications
Available grades: Industrial, USP, and pharmaceutical grade
Key difference: PG is the only glycol safe for food and pharmaceutical use. MEG is toxic — never substitute MEG where PG is specified
Decision Framework: Which Glycol Do You Need?
| Your Application | Recommended Glycol | Why |
|---|---|---|
| Automotive antifreeze | MEG | Cost-effective, proven performance, wide freeze protection |
| PET bottle resin | MEG (99.9%) | Fiber/PET grade purity required |
| Polyester fiber spinning | MEG (99.9%) | Low DEG and iron content critical |
| UPR / fiberglass | DEG | Excellent reactivity with unsaturated acids |
| Gas dehydration | TEG | Low vapor pressure, minimal losses, deep dewpoint |
| Air sanitizing | TEG | Low volatility, effective humidification |
| Food-grade antifreeze | PG | FDA GRAS status, non-toxic |
| Pharmaceutical solvent | PG (USP) | USP grade purity, safe for ingestion |
| HVAC heat transfer | MEG | Low cost, good thermal properties |
| Construction coatings | PG | Low odor, freeze protection, coalescent |
Sourcing from VASTEC
VASTEC supplies all four glycols from trusted Chinese manufacturers with consistent quality and competitive pricing:
- MEG — 99% industrial and 99.9% fiber/PET grade
- DEG — Industrial grade, ≥99%
- TEG — Technical grade, ≥99%
- PG — Industrial, USP, and pharmaceutical grade
All products shipped with Certificate of Analysis. SGS or Bureau Veritas inspection available. Flexible packaging: 230kg drums, 1000L IBC, or flexitank. Payment terms: LC, TT, CAD.