Glycol Concentration Testing
In glycol concentration testing, glycol is used as it possesses exceptional heat transfer efficiency which makes it a standard fluid for heating and cooling applications such as heating, ventilations and air conditioning (HVAC).
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- Overview
- Scope, Applications, and Benefits
- Test Process
- Specifications
- Instrumentation
- Results and Deliverables
Glycol Concentration Testing - Overview
Glycol concentration testing quantifies the proportion of ethylene glycol (EG) or propylene glycol (PG) in coolant, antifreeze, and heat transfer fluid solutions. Accurate glycol concentration measurement is essential for ensuring that cooling systems provide adequate freeze protection, boiling point elevation, and corrosion inhibition performance across the intended service temperature range.
This service supports automotive and industrial coolant manufacturers, maintenance programs, and quality control laboratories in verifying coolant formulations, assessing in-service fluid condition, and confirming compliance with OEM and industry coolant specifications.
Scope, Applications, and Benefits
Scope
Glycol concentration testing is used to quantify and characterise the composition of coolant fluids, ensuring optimal thermal performance and system protection. It determines the levels of key glycol types and correlates concentration with critical operating properties.
- Measurement of ethylene glycol (EG) and propylene glycol (PG) in % v/v or % w/w
- Prediction of freeze and boiling points based on glycol concentration
- Analysis applicable to both fresh and in-service (used) coolant samples
- Identification and differentiation of EG and PG in mixed or unknown formulations
- Correlation with analytical techniques such as refractometry, density measurement, and titration
Applications
- Automotive and heavy-duty engine coolant QC
- Industrial chiller and HVAC heat transfer fluid monitoring
- Marine engine cooling system coolant testing
- Solar thermal system fluid characterisation
- Glycol in wastewater or de-icing fluid monitoring
Benefits
- Ensures correct freeze and boiling protection in cooling systems
- Prevents engine damage from incorrectly mixed coolants
- Supports preventive maintenance and fluid change intervals
- Identifies coolant dilution, contamination, or leakage
- Enables compliance with ASTM D3306, D6210, AS 2108 coolant specifications
Glycol Concentration Testing - Test Process
Sample Collection
Collect coolant in sealed containers; note condition.
1Refractometer Screening
Estimate glycol % using refractive index.
2Confirmatory Analysis
Validate type and concentration via GC or ASTM method.
3Reporting
Report glycol %, type, freeze/boiling point vs specs.
4Glycol Concentration Testing - Technical Specification
| Parameter | Details |
|---|---|
| Methods | Refractometry, GC, titration (ASTM D1123), density |
| Concentration Range | 0–70% v/v glycol in water |
| Freeze Point Range | 0 °C to -67 °C (EG–water) |
| Accuracy (refractometer) | ±1–2 %v/v |
| Accuracy (GC) | ±0.5 %v/v |
Instrumentation Used for Testing
- Temperature-compensated refractometer (EG/PG scales)
- Gas chromatograph (GC-FID) for glycol identification and quantification
- Density meter (oscillating U-tube)
- pH meter and conductivity meter (coolant condition assessment)
- Analytical balance and titration apparatus (ASTM D1123)
Results and Deliverables
- Glycol type (EG or PG) and concentration (%v/v, %w/w)
- Calculated freeze point and boiling point
- Comparison to OEM or specification freeze protection requirements
- pH, conductivity, and reserve alkalinity (if full coolant panel requested)
- Full glycol concentration test report with method traceability
Partnering with Infinita Lab for Optimal Results
Infinita Lab addresses the most frustrating pain points in the Glycol Concentration testing process: complexity, coordination, and confidentiality. Our platform is built for secure, simplified support, allowing engineering and R&D teams to focus on what matters most: innovation. From kickoff to final report, we orchestrate every detail—fast, seamlessly, and behind the scenes.
Looking for a trusted partner to achieve your research goals? Schedule a meeting with us, send us a request, or call us at (888) 878-3090 to learn more about our services and how we can support you. Request a Quote
Frequently Asked Questions
Ethylene glycol (EG) provides slightly better thermal performance and is used in most automotive and industrial applications. Propylene glycol (PG) is less toxic and is preferred in food processing and solar heating systems where incidental contact with humans or food is possible.
Above approximately 70% glycol concentration, the freeze point of the mixture begins to rise again (the eutectic point is near 67% EG), and heat transfer performance decreases significantly. Additionally, viscosity increases substantially, reducing coolant flow and heat transfer efficiency.
Refractometers measure refractive index, and EG and PG have different refractive index–concentration relationships. Dedicated EG or PG scales on hand-held refractometers are not interchangeable — using the wrong scale gives an incorrect concentration reading. GC analysis can definitively identify glycol type.
Most OEMs recommend coolant condition checks annually or every 25,000–50,000 km for automotive systems. Industrial systems should be checked at least annually or after any significant system maintenance, water makeup, or suspected contamination event.
Yes. GC analysis can identify the presence of unexpected glycol types, degradation by-products (glycolic acid, diethylene glycol), or other contaminants. Abnormal pH, conductivity, or inhibitor depletion indicated during a full coolant panel can also signal contamination or degradation.
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