DOWFROST LC 25 Heat Transfer Liquid
Harmonization Code : 3824.90.90 | Prepared binders for foundry moulds or cores; chemical products and preparations of the chemical or allied industries
Main features
- Made with Dow PURAGUARD™ USP/EP grade PG (>99.8% purity)
- Freeze protection to –10°C (14°F)
- Formulated for high-efficiency heat transfer
Product Description
DOWFROST™ LC 25 is a ready-to-use, propylene glycol heat transfer fluid (HTF) formulated at a 25 vol% PG concentration (PG25). It contains a specialized corrosion-inhibitor package that slows oxidation commonly observed in glycol-based HTFs. The inhibitor package also stabilizes pH and reserves alkalinity, reducing corrosivity toward common system metals such as copper, brass, carbon steel, cast iron, and aluminum used in high-efficiency cooling systems.
DOWFROST™ LC 25 is made with Dow PURAGUARD™ USP/EP grade propylene glycol (>99.8% purity), which meets strict United States Pharmacopeia (USP) and European Pharmacopoeia (EP) standards. Compared with lower-grade glycols, the lower impurity content of PURAGUARD™ PG reduces the formation of degradation byproducts that lead to odor, discoloration, and shortened fluid service life, effects that corrosion inhibitors alone cannot prevent.
Key Features:
- 25% propylene glycol concentration (PG25)
- Made with Dow PURAGUARD™ USP/EP grade PG (>99.8% purity)
- Corrosion-inhibited glycol protects copper, brass, steel, cast iron, and aluminum
- Maintains pH stability and reserve alkalinity for longer fluid life
- Freeze protection to –10°C (14°F)
- Dyed fluorescent yellow-green for easy leak identification
- Formulated for high-efficiency heat transfer in industrial and data-center cooling loops
The combination of high-purity propylene glycol and optimized corrosion inhibitors makes DOWFROST™ LC 25 a chemically stable, low-impurity heat transfer fluid suitable for long-term operation in industrial and data center cooling systems.
Uses:
- Datacom and telecom equipment cooling loops
- Direct-to-chip liquid cooling for high-performance processors
- Data center thermal management and cooling systems
DS-LC25
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Technical Specifications
Thermal Properties
Physical Properties
Additional Information
Typical Properties and Applications of DOWFROST™ LC 25
Typical Properties
| Propylene Glycol Concentration | 25 vol% |
| Freezing Point | 14 °F (–10 °C) |
| Boiling Point @ 760 mmHg | 101.4 °C |
| Specific Gravity (25/25 °C) | 1.030–1.036 |
| pH | 8.0–10.5 |
| Reserve Alkalinity | >6.0 mL 0.1 N HCl |
| Thermal Conductivity @ 50 °C | 0.485 W/m·K |
| Specific Heat @ 50 °C | 4.13 kJ/kg·K |
| Viscosity | 2.72 mPa·s @ 20 °C 1.15 mPa·s @ 50 °C |
| Volume Expansion (–10 to 90 °C) | 5.1 % |
| Sulfate Content | <10 ppm |
| Chloride Content | <5 ppm |
| Total Hardness (as CaCO₃) | <20 ppm |
Typical values shown for reference only and should not be used as specifications.
Recommended for
- Datacom and telecom equipment cooling loops
- Direct-to-chip liquid cooling for high-performance processors and accelerators
- Data center thermal management and rack-level liquid cooling systems
- HVAC and process cooling systems requiring long-term fluid stability
- Systems where fluid cleanliness, material compatibility, and corrosion control are critical
Propylene Glycol Concentration vs. Refractive Index and Freezing Point
Quick takeaways
- Higher PG concentration → higher refractive index
- Higher PG concentration → lower freezing point
- Nominal concentration ≈ 25 vol%
- Freezing point ≈ –9.6 °C (14.7 °F)
How to use this table
- Measure refractive index at 20 °C or 25 °C
- Match value to the corresponding PG concentration.
- Determine the corresponding freezing point (freeze protection).
| PG Concentration (wt%) | PG Concentration (vol%) | Refractive Index (20 °C) | Refractive Index (25 °C) | Freezing Point (°F) | Freezing Point (°C) |
|---|---|---|---|---|---|
| 18 | 17.8 | 1.3542 | 1.3536 | 19.9 | –6.7 |
| 19 | 18.8 | 1.3555 | 1.3548 | 19.4 | –7.0 |
| 20 | 19.8 | 1.3568 | 1.3561 | 18.9 | –7.3 |
| 21 | 20.8 | 1.3581 | 1.3573 | 18.1 | –7.7 |
| 24 | 23.8 | 1.3618 | 1.3611 | 15.6 | –9.1 |
| 25 | 24.9 | 1.3630 | 1.3622 | 14.7 | –9.6 |
| 26 | 25.9 | 1.3643 | 1.3634 | 13.6 | –10.2 |
| 27 | 26.9 | 1.3655 | 1.3646 | 12.6 | –10.8 |
| 28 | 27.9 | 1.3667 | 1.3659 | 11.5 | –11.4 |
| 29 | 29.0 | 1.3679 | 1.3670 | 10.2 | –12.1 |
| 30 | 30.0 | 1.3691 | 1.3691 | 9.0 | –12.8 |
| 31 | 31.0 | 1.3702 | 1.3693 | 7.7 | –13.5 |
| 32 | 32.0 | 1.3714 | 1.3705 | 6.4 | –14.2 |
| 33 | 33.1 | 1.3725 | 1.3716 | 5.0 | –15.0 |
| 34 | 34.1 | 1.3737 | 1.3728 | – | –15.8 |
| 35 | 35.1 | 1.3748 | 1.3739 | 1.9 | –16.7 |
Refractive index values are reference data for concentration verification and should be measured using calibrated instruments at the specified temperatures.
Corrosion Performance of DOWFROST™ LC 25
Long-term reliability of direct-to-chip liquid cooling systems depends on strict control of corrosion across all wetted materials. Comparative corrosion testing demonstrates that DOWFROST™ LC 25 delivers excellent corrosion protection across all metals tested , achieving orders-of-magnitude lower corrosion rates than water and uninhibited propylene glycol.
Visual comparison of metal corrosion after exposure to water, uninhibited propylene glycol, and DOWFROST LC 25.
| Metal | Water (mpy) | Uninhibited PG (mpy) | DOWFROST™ LC 25 (mpy) |
|---|---|---|---|
| COPPER | 0.08 | 0.16 | 0.03 |
| SOLDER | 3.14 | 34.70 | 0.04 |
| BRASS | 0.23 | 0.20 | 0.07 |
| MILD STEEL | 9.69 | 9.80 | 0.02 |
| CAST IRON | 21.20 | 16.20 | 0.02 |
| ALUMINUM | 13.20 | 1.80 | 0.31 |
Corrosion performance evaluated using ASTM D1384 testing at 190 °F (88 °C) for two weeks with constant air bubbling. Glycol solutions were prepared at 30 vol%. Corrosion rates are reported as mils penetration per year (mpy). Corrosion rates above 0.5 mpy (2.5 mpy for aluminum) generally indicate insufficient corrosion protection.
Chemical Compatibility with Wetted Metals
DOWFROST™ LC heat transfer fluids are designed to be chemically compatible with common system metals and alloys at bulk fluid temperatures up to 90 °C (194 °F).
- Brass (<15% zinc, chrome plated, nickel plated)
- Carbon steel
- Copper and copper alloys (<15% zinc)
- Stainless steel (solution treated and passivated)
Chemical Compatibility with Elastomers and Plastics
DOWFROST™ LC 25 is formulated for long-term compatibility with common elastomers and plastics at bulk fluid temperatures up to 90 °C (194 °F). Always confirm with material suppliers for specific formulations.
| Elastomers and Plastics | Compatibility with DOWFROST™ LC 25 |
|---|---|
| Acrylonitrile butadiene rubber (NBR) | ★☆☆☆☆ Most compositions not recommended above 40 °C |
| Polyoxymethylene (POM) | ★☆☆☆☆ Not recommended above 30 °C |
| Ethylene Propylene Diene Monomer (EPDM) | ★★★★☆ Acceptable up to at least 75 °C |
| Fluoroelastomer (FKM) | ★★☆☆☆ Some compositions not recommended above 40 °C |
| Fluorinated Ethylene Propylene (FEP) | ★★★★★ Acceptable up to at least 90 °C |
| Polyamide (PA) | ★☆☆☆☆ Most compositions not recommended above 40 °C |
| Polychloroprene (CR) | ★★☆☆☆ Some compositions not recommended above 40 °C |
| Polyethylene (PE) | ★★★★☆ Acceptable up to at least 75 °C |
| Polyphenylene Sulfide (PPS) | ★★★☆☆ Acceptable up to at least 60 °C |
| Polytetrafluoroethylene (PTFE) | ★★★★★ Acceptable up to at least 90 °C |
| Polypropylene (PP) | ★★★★☆ Acceptable up to at least 75 °C |
| Polysulfone / Polyphenylsulfone (PSU, PPSU) | ★★★★☆ Acceptable up to at least 75 °C |
| Silicone | ★☆☆☆☆ Most compositions not recommended above 40 °C |
Compatibility ratings are qualitative and provided as general guidance. Actual compatibility may vary depending on the specific elastomer or plastic formulation used by the component manufacturer and operating conditions.
Frequently Asked Questions
▶ Is DOWFROST™ LC 25 compatible with elastomers and plastics used in liquid cooling systems?
DOWFROST™ LC 25 is formulated to maintain chemical compatibility with a wide range of elastomers and plastics commonly used in liquid cooling systems operating at bulk fluid temperatures up to 90 °C (194 °F).
Materials such as PTFE and FEP exhibit excellent compatibility at elevated temperatures, while EPDM, polyethylene (PE), polypropylene (PP), and polysulfone-based polymers (PSU, PPSU) are generally suitable for operation up to approximately 75 °C.
Some elastomers and plastics, including NBR, silicone, polyamide (PA), polyoxymethylene (POM), and certain fluoroelastomers (FKM), may have lower recommended temperature limits or reduced long-term stability when exposed to propylene glycol–based fluids.
▶ Can DOWFROST™ LC 25 heat transfer fluid be diluted?
DOWFROST™ LC 25 is a ready-to-use heat transfer fluid and should not be diluted. It is formulated with the correct concentration of corrosion inhibitors to protect datacom equipment cooling systems (DECS) and other liquid cooling loops.
If dilution is unavoidable, only purified water—distilled, deionized (DI), or reverse osmosis (RO)— should be used.
Minimum water quality limits for any unavoidable dilution:
| Total Chlorides (as Cl⁻) | < 25 mg/L |
| Total Sulfates (as SO₄²⁻) | < 25 mg/L |
| Total Hardness (as CaCO₃) | < 50 mg/L |
| Total Iron (as Fe) | < 1 mg/L |
| Electrical Conductivity | < 50 µmhos/cm |
| pH | 5 < pH < 9 |
▶ Why does DOWFROST™ LC 25 have higher electrical conductivity than purified water, and is it a concern?
DOWFROST™ LC 25 contains corrosion inhibitors, pH buffers, and stabilizing additives that are intentionally added to protect metals and maintain long-term fluid performance. These additives increase ionic content, resulting in electrical conductivity values typically above 2,000 µmhos/cm.
The higher conductivity is not a concern because DOWFROST™ LC 25 is used in closed-loop liquid cooling systems, where the fluid is fully contained and isolated from electronic circuits.
