Green: Preferred
The result is within the matrix’s preferred range. Continue routine maintenance and trend the result against future quarterly samples.
Coolant Condemning Limits
C.U.R.E. Technical Reference
Coolant Condemning Limits
A coolant analysis becomes useful when laboratory results are translated into condition, risk, and action. This matrix provides a structured screening reference for evaluating coolant protection, chemistry, contamination, and cooling system distress.
Color-Coded Risk Levels Chemistry and Contamination C.U.R.E. Decision Support
System Condition
From Results to Decisions
What Is a Condemning Limit?
A condemning limit is a screening boundary used to identify results that have moved away from the preferred operating range. It helps maintenance teams prioritize investigation and corrective action.
A limit is not a diagnosis by itself. A laboratory value must be considered with coolant type, engine design, operating history, sample quality, maintenance records, visible condition, and trends from earlier samples.
The C.U.R.E. Protocol evaluates the combined report instead of making a recommendation from one number alone. It uses the findings to Collect the facts, Understand system condition, Recommend the proper response, and Execute the field procedure.
Condition Scale
How to Read the Four Levels
The color columns communicate increasing distance from the preferred range. They help organize urgency, but they do not replace technical interpretation.
Yellow: Monitor
The result has moved away from the preferred range. Review related indicators, operating history, and prior laboratory trends.
Orange: Correct
The result indicates a stronger condition concern. Technical review and a defined corrective maintenance plan should be prioritized.
Red: Critical
The result is substantially outside the preferred range. Prompt investigation, verification, and corrective action are required.
Published Reference
Coolant Condemning Limits Matrix
Use the chart for a quick visual review. The accessible table below presents the same published values in text.
Matrix values are screening references. Always interpret results with the laboratory report, coolant formulation, equipment requirements, operating history, and sample trend.
Accessible Limits Table
| Parameter | Green | Yellow | Orange | Red |
|---|---|---|---|---|
| Freezepoint (°F) | Approximately −34°F | −20°F to −34°F | −5°F to −20°F | Greater than −5°F |
| Antifreeze | 50% | 40–50% or 50–60% | Less than 40% or greater than 60% | Less than 30% or greater than 70% |
| Nitrites | 2,400–3,000 ppm | 1,500–2,400 ppm | 500–1,500 ppm | Less than 500 ppm |
| pH | 8.0–10.5 | 7.5–8.0 or 10.5–11.0 | 7.0–7.5 or 11.0–11.5 | Less than 7.0 or greater than 11.5 |
| Reserve Alkalinity | 6–10 mg KOH/g | 4–6 or 10–12 mg KOH/g | 2–4 or 12–14 mg KOH/g | Less than 2 or greater than 14 mg KOH/g |
| Color | Clear, correct color | Slight discoloration | Murky or particles | Dark or sludgy |
| Conductivity | 2,000–4,000 µS/cm | 1,500–2,000 or 4,000–5,000 µS/cm | 1,000–1,500 or 5,000–6,000 µS/cm | Less than 1,000 or greater than 6,000 µS/cm |
| Contaminants | None visible | Minor | Visible debris | Severe |
| Iron (Fe) | Less than 10 ppm | 10–20 ppm | 20–50 ppm | Greater than 50 ppm |
| Lead (Pb) | Less than 5 ppm | 5–15 ppm | 15–30 ppm | Greater than 30 ppm |
| Copper (Cu) | Less than 5 ppm | 5–15 ppm | 15–30 ppm | Greater than 30 ppm |
| Aluminum (Al) | Less than 5 ppm | 5–15 ppm | 15–30 ppm | Greater than 30 ppm |
| Silicon (Si) | Less than 10 ppm | 10–20 ppm | 20–50 ppm | Greater than 50 ppm |
| Potassium (K) | Less than 5 ppm | 5–15 ppm | 15–30 ppm | Greater than 30 ppm |
| Sodium (Na) | Less than 10 ppm | 10–20 ppm | 20–40 ppm | Greater than 40 ppm |
| Boron (B) | Less than 10 ppm | 10–20 ppm | 20–40 ppm | Greater than 40 ppm |
| Magnesium (Mg) | Less than 5 ppm | 5–15 ppm | 15–30 ppm | Greater than 30 ppm |
| Calcium (Ca) | Less than 10 ppm | 10–20 ppm | 20–40 ppm | Greater than 40 ppm |
| Phosphorus (P) | Less than 10 ppm | 10–20 ppm | 20–40 ppm | Greater than 40 ppm |
| Zinc (Zn) | Less than 10 ppm | 10–20 ppm | 20–40 ppm | Greater than 40 ppm |
| Molybdenum (Mo) | Less than 5 ppm | 5–15 ppm | 15–30 ppm | Greater than 30 ppm |
| TDS | Less than 2,000 µS/cm | 2,000–4,000 µS/cm | 4,000–6,000 µS/cm | Greater than 6,000 µS/cm |
Swipe left and right to view every condition level.
Understanding the Findings
What the Test Groups Can Reveal
No result exists in isolation. Related indicators should be reviewed together to distinguish coolant condition from contamination, corrosion, additive chemistry, and sampling effects.
Protection and Coolant Condition
Freezepoint, antifreeze percentage, nitrites, pH, reserve alkalinity, color, and conductivity help describe concentration, inhibitor protection, chemical stability, and the coolant’s ability to remain service ready.
Wear and Corrosion Indicators
Iron, lead, copper, and aluminum can identify distress involving ferrous components, solder or lead-containing materials, copper or brass components, and aluminum surfaces. Trends and equipment metallurgy matter.
Contamination and Chemistry
Silicon, potassium, sodium, boron, magnesium, calcium, phosphorus, zinc, molybdenum, visible contaminants, and dissolved solids can help identify outside material, water quality problems, additive chemistry, or incompatible coolant mixing.
Interpretation Context
Why One Number Is Not Enough
Open each section to see the supporting information needed before choosing a maintenance response.
Coolant type and original formulation
Different coolant formulations may use different inhibitor packages and starting chemistry. A result that is expected in one formulation may be abnormal in another. Identify the coolant type before interpreting additive elements.
Trend history and quarterly analysis
A single sample is a snapshot. Quarterly coolant analysis shows whether iron, conductivity, contamination, inhibitor protection, or other conditions are stable, improving, or deteriorating. Rate of change can be as important as the current value.
Maintenance and operating history
Coolant additions, overheating events, repairs, chemical treatments, water additions, leaks, and recent flushing can change laboratory results. These facts should accompany the report whenever possible.
Sampling quality and field verification
The sample must represent the circulating coolant. Contaminated containers, residue at the sampling point, settled material, or an unrepresentative location can distort results. Verify unexpected findings with inspection and repeat sampling when appropriate.
OEM requirements and laboratory guidance
This matrix supports condition screening. It does not replace the laboratory’s interpretation, equipment manufacturer requirements, mechanical inspection, or site-specific safety and maintenance procedures.
Put the Matrix Into Action
Use the C.U.R.E. Protocol
The matrix shows where results fall. C.U.R.E. goes further by reviewing the report as a system, identifying exceeded limits, organizing the findings, assigning condition guidance, recommending the appropriate treatment path, and providing an execution procedure.
Proactive Cooling System Management
Do Not Stop at the Laboratory Result
Upload the coolant analysis to C.U.R.E. and convert laboratory data into understandable findings, a specific recommendation, and an executable corrective action plan.