Frequently asked questions
- How to select the right sample analysis package?
The best-fit analysis package depends on the application, the frequency of sampling, the condition of the coolant, the condition of your engine/system, the reason for taking a sample, … Here below are some general guidelines.
- Select BRONZE if you perform already regular checks and are closely monitoring your coolant quality (f.e. via monthly sampling). It also serves as good alternative for less accurate in-field measurements. This will result in better insights on the current condition of your coolant properties
- Select SILVER if you wish to obtain an overall view on your cooling system via determination of corrosion, contaminants & other metal components. This package is also ideal to detect potential deterioration of your coolant by analysing degradation products and other anions.
- Select GOLD if you want to attain a complete chemical evaluation of the coolant, including a detailed corrosion inhibitor analysis. This package gives you a full picture on the composition of the coolant, its condition and a potential contamination or deteriorationt.
- Select the MICROPATCH as extra analysis in case of hazy samples or samples with clearly visible deposits. By separating the deposits via filtration, and a microscopic analysis of the deposits, interesting learnings will lead to better understanding of the nature of the deposit, the cause and eventually how to address the problem.
- What is pH?
pH is the negative decadic logarithm of the hydrogen ion concentration. It is a scale to specify how acidic or basic a water based solution is referring to the pH of pure water. Pure water displays a pH of 7 which is also designated as “neutral” or “neutral pH”. Water based media with pH values below 7 are called acidic, pH values above 7 designate the basic pH range. The maximum possible pH of water based systems is 14 (e.g. concentrated caustic soda) and the lowest is 0 (e.g. concentrated mineral acids).
As coolants (concentrates and ready mixes) are strictly speaking due to the presence of glycol no longer water based systems, the correct measurement of pH value in a coolant in operation necessitates a specific procedure that should be carried out on the basis of a sample in a specialized laboratory. Measurement of pH of coolants with commercially available pH strips will produce misleading results. The correctly measured pH in a coolant sample is a good indicator of the end of life of a coolant, in general terms a pH of 7 should lead to a closer inspection of the coolant and potentially to a renewal of the coolant.
The desired operating pH range of a coolant is pH 7.5 - 9 as many metals and metal alloys present in a cooling system are least prone to corrosion in that pH range and most additives and corrosion inhibitors are at their optimum activity in this pH range.
- What is density and how is it affected by base fluid concentration?
Density by definition is mass per unit volume.
Example: 1 liter of water weighs 1.0 kg at 4°C, so the density in this example is 1 kg/liter. At this temperature water has its maximum density or lowest volume since the water molecules are optimally arranged.
Obviously density of a substance varies with temperature and pressure. Pressure dependency is typically limited for solids and liquids, but is much higher for gases.
For binary systems - such as a water/glycol mixture - density varies also with the concentration ratio of both substances. Considering a mixture of water and MEG at a certain temperature, the density moves to higher values by adding more MEG to the mixture.
As a result, 90vol% Havoline® XLC has a higher density (1.107kg/L at 20°C) compared to 40vol% Havoline® XLC (1.056kg/L).
Mixtures of water and MPG however do not follow the same behaviour. At a given temperature the density of water/MPG will start to decrease once the concentration of MPG has reached about 80vol%. The reason for this is a steric hindrance of the methyl group of the MPG molecule for MPG concentrations above 80vol%, which is the result of a non-optimal arrangement of water and MPG on molecular level.
- What is RA?
RA stands for “Reserve Alkalinity” and is a measure for the capacity of a coolant to take up acid, also called “buffer capacity”. Reserve Alkalinity is measured in terms of milliliters of 0.1 normal Hydrochloric Acid (0.1N HCl). The more milliliters the coolant can take up, down to a pH of 5.5 as defined in ASTM D 1121, the higher the Reserve Alkalinity is.
A high Reserve Alkalinity is often considered as a quality and performance guarantee. However, the RA has always to be considered in connection with the coolant technology of the respective coolant, i.e. Traditional, Hybrid, Lobrid and OAT–Technology and with the intended application. The RA of Traditional and Hybrid Technology ranges typically from 4-8 whereas the RA of OAT Technology and Lobrid Technology are typically situated around 3 ml 0.1 N HCl (50 vol% Ready Mixes, for more info please refer to our Product Information Leaflets). For historical reasons, in many heavy duty application high RA is still preferred, whereas the low RA technologies seemed to be more appropriate for passenger car and light duty vehicles. With increasing heat and mechanical stress in both, heavy duty and passenger car applications, also the low RA coolant Technologies, OAT and Lobrid, find their way into heavy duty applications. The additives providing high reserve alkalinity tend to become unstable under high heat and mechanical stress.
- What is Electric Conductivity?
Electrical Conductivity (EC) or specific conductance represents the ability of a matter (solid, liquid, gas and plasma) to allow the transport of charged particles. A high EC indicates a material that readily allows electric current.
EC is commonly signified by the Greek letter σ (sigma), but also κ (kappa) and γ (gamma) are sometimes used. The SI unit (International System of Units) of EC is Siemens per meter (S/m), whereas for engine coolants and heat transfer fluids (HTFs) µS/cm is often used.
In electrolytes such as an engine coolant or HTF, electrical conduction happens by ions - which is the collection of anions and cations - traveling, each carrying an electrical charge. The conductivity of ionic solutions/electrolytes varies with concentration of ions and temperature. Think about distilled water as an almost insulator whereas salt water is a reasonable fair conductor.
As can be understood from the above, the quality of the dilution water itself (linked to the total ion content) plays an important role in the EC of the coolant. Secondly, the inhibitor technology is affecting the EC level as well. And in addition, when the coolant or HTF is circulating in the system it might pick up remnants from machining and other contaminants, all having an impact on the overall EC. It is therefore incorrect to deduct from the EC value the dilution ratio of an engine coolant or HTF.