WATER IN OIL SENSOR
A hand held instrument for taking readings of water content in all oils and fuel oils measuring % of water saturation. Readings can be taken as % of saturation with 100% being the maximum or readings can be taken in ppm by programming the unit with the known ppm value of saturation of any given oil.
The water sensor is supplied pre-programmed for ppm of transformer oils.
Oil composition
Modern lubrication oils are designed to hold a certain amount of water in suspension, when this level is exceeded the water becomes FREE and separates from the oil, typically new lubrication oils have a value of >500ppm.
Bio-degradable oils generally have a higher level of water retention capability.
Pure base oils have very limited solubility, which is related to the ratios of paraffin, naphthenic, and aromatic compounds. The saturation point at 20 °C varies from approximately 30 parts per million (ppm) of paraffin oils to over 200 ppm of fully aromatic liquids, but it is typically
between 40 to 80 ppm. Solubility may increase significantly with the use of additives.
Oxidation products also increase solvating efficiency. Mineral-based transformer oils typically have very little additives and therefore have low solubility like base oil, whereas lubrication oils with greater amounts of additives generally have much higher solubility.
Water Content DIESEL FUEL
Most diesel fuels will have a dissolved water content which is normal and harmless. Typically at room temperature this dissolved water content could be around 200 ppm (.02%). As water content increases it can no longer exist as dissolved water and becomes present as free water. The water content becomes critical at concentrations of .1% and above.
Moisture measurement.
Traditionally, water in oil has been measured by Karl Fisher titration (a method for determining the moisture content of a sample) and expressed in ppm, which is the total absolute water content, thus not giving any indication whether water is dissolved or free. However, due to differences in oil types and difficulty in predicting aging effects, ppm values are often not sufficient. Therefore, relative values like water activity (aw) are useful parameters for setting alarms in control systems and for monitoring water content.
Solubility of fresh and used engine lubrication oil.
Dealing with water in hydraulic fluid
Oil becomes cloudy when it is contaminated with water above its saturation level. The saturation level is the amount of water that can dissolve in the oil's molecular chemistry and is typically 200 - 300 ppm for every 1ml of oil at 68°F (20°C) for mineral oils. If hydraulic oil is cloudy it indicates that water is present. A guide to water contamination is 10,000 ppm is equivalent to 1% water in a hydraulic system.
Why is water in hydraulic fluid bad?
Water in hydraulic fluid:
- Depletes some additives and reacts with others to form corrosive by-products which attack some metals.
- Reduces lubricant film-strength, which leaves critical surfaces vulnerable to wear and corrosion.
- Reduces filterability and clogs filters.
- Increases air entrainment ability and causes bacterial growth.
- Increases the likelihood of cavitations occurring.
Dissolved Water
Dissolved water contamination is the least harmful of the three types of water. Dissolved water is a function of the environment- Relative humidity, temperature, and oil type will normally determine what dissolved water content will be. Dissolved water does not affect lubricity.
Emulsified Water
Emulsified water is water that has been mixed, homogenized and/or mechanically emulsified in the lube oil to form extremely strong emulsions. Strong in the sense that gravity or other devices will not work in separating the two phases. Emulsified water is capable of reducing lubricity.
Free Water
Free water is free to separate and settle to the base of the reservoir. Free water is the most damaging, because it can displace Lube oil and allow metal to metal contact of rotating equipment.The presence of free water needs to be monitored online effectively. Free water in oil can cause quick and costly breakdowns. It can happen so fast that in many cases, water in oil can be treated as a more serious contamination problem than metal particle contamination! Since water contamination can occur at any time. It is possible that serious damage can be caused on bearings and other lubricated component without the user knowing it is happening at the time.
How much water is too much?
A number of factors need to be considered when selecting water contamination targets, including the type of hydraulic system and reliability objectives for the equipment. It's always wise to control water contamination at the lowest levels that can reasonably be achieved, ideally below the oil's saturation point at operating temperature.
Click here to view to Water in Oil Sensor .pdf
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