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Testing Water Used For Flushing Systems Can Prevent Premature Engine Failure
Even the best cooling system maintenance practices will fail if the source water you're using to flush the system doesn't meet engine manufacturer and ASTM specifications. Pre-mixed coolants take much of the guesswork out using a proper source water, but when mixing your own coolant formulations or flushing your systems with water from an on-site source, analysis is highly recommended to make sure the water meets specifications.
RECOMMENDED SCALING PROPERTY LEVELS
| Scaling Properties | Definition | Specification or Recommended Levels |
| Total Hardness | The sum of calcium and magnesium in a water - hardness forms scale | 170 ppm or less (ASTM) |
|---|---|---|
| Iron | Immediately forms scale providing food for iron bacteria - the biological end product of the iron bacteria food cycle being sulfur-type acids | 0.5 ppm or less |
| Silica | Combines with calcium to form silicate scale - scale formed will be hard and highly insulating | 30 ppm or less |
| Sulfate | Combines with calcium and magnesium to form scale or converts to sulfuric acid | 100 ppm or less (ASTM) |
DEPOSIT CHARACTERISTICS
Carbonate
A carbonate deposit is usually granular and can be very porous. The crystals
of calcium carbonate are large, but will usually be matted together with
finely divided particles of other materials so that the scale looks dense
and uniform. A carbonate deposit can be identified by dropping it into
an acid solution. Bubbles of carbon dioxide will effervesce from the scale.
Sulfate
A sulfate deposit is much harder and denser than a carbonate deposit because
the crystal structure is smaller. A sulfate deposit is brittle, does not
pulverize easily and will not effervesce when dropped into an acid solution.
Silica
A high silica deposit is very hard, highly insulating and resembles porcelain.
The crystals of silica are extremely small, forming a very dense, impenetrable
scale. This scale is very brittle, very difficult to pulverize and not
soluble in hydrochloric acid.
RECOMMENDED ACID PITTING PROPERTY LEVELS
| Acid Pitting Compound | Definition | Specification or Recommended Level |
| Chloride | Forms salt or hydrochloric acid to pit metal | 40 ppm or less (ASTM) |
|---|---|---|
| Sulfate | Under acidic conditions, can form sulfuric acid | 100 ppm or less |
| pH | Measures a water’s acidity or alkalinity | 5.5 - 9.0 (ASTM) |
| Total Dissolved Solids | Solids indicate the level of contaminants present in the water. Excessive dissolved solids can cause a coolant to foam. | 340 ppm or less (ASTM) |
ADDITIONAL WATER PROPERTIES TO CONSIDER
Free Carbon Dioxide - 60 ppm or less
Phenolphthalein Alkalinity - water’s natural alkalinity
Methyl Orange Alkalinity - water natural reserve or ability to neutralize acid - although other properties in the water may cause variance, less than 20-30 ppm is recommended
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Higher - water will release cavitating carbon dioxide gas and forms carbonic acid that will pit metal.
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Lower - at increased temperatures, water becomes acidic, causing pitting.
Specific Conductance - the natural resistance of the water against galvanic electrical current between the engine and cooling system; 500 micromohos or less is recommended
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