Water is a chemical contaminant in oils and at 100% relative humidity will exist as bubbles in hydraulic systems. Where water is present in a system, the effects can be dangerous if not monitored and controlled properly.
When free water exists in an oil, the bubbles it forms can interfere with particle counts, and therefore effect the desired outputs. Typically excess water will give a dirtier reading than actual system cleanliness.
At MP Filtri we offer water sensor options with our products which can monitor levels of water in your hydraulic oil allowing you to keep your system in good condition. Poor water monitoring and control can lead to some or all of the following symptoms;
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✦Shorter component life.
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✦Wire erosion and vaporous cavitation.
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✦Hydrogen embrittlement.
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✦Oxidation.
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✦Component wear.
All of these can exist to varying degrees of severity depending on individual system designs, however the results can be catastrophic for both equipment and personnel. At MP Filtri, we recommend that you set a maximum alarm setting for water content in your oil, and where possible aim to operate well within this limit so that water never becomes a problem.
In the interests of system life extension, oil should always remain relatively translucent. Where high concentrations of water are present, oil may turn cloudy or opaque and consideration should be made as to whether the oil should be replaced with new.
To remove the risk of water induced failures, the following list can be used for consideration.
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✦Oil management and handling
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✦Use of breathers or tank headspace protection
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✦Washing down of systems and protection during this operation.
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✦IP rating of the equipment fitted to the system and its susceptibility to moisture ingress.
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✦Formation of condensate on the surrounding area.
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✦Secondary sealing for critical applications.
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✦Store oil drums indoors.
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✦Periodic draining of particularly susceptible systems.
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✦Operator training.
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Aeration of fluids can cause many problems in a hydraulic and lubrication oil system. When it comes to contamination monitoring, entrained bubbles in a fluid can cause instability in output readings as the tiny bubbles can be “seen” by the sensor within the product. Where systems have large amounts of aeration, this can lead to higher contamination reading than would normally be expected, and therefore confidence in system performance can be questionable.
There are many products on the market, like automatic air vents, which can alleviate the symptoms of aerated fluids, but these alone cannot completely remove the problem and as a result we recommend that preventative measures be taken when designing systems to not only improve the output from your particle counter, but to also improve overall system life and performance.
We recommend when measuring particulate contaminants that steps be taken to ensure that the product is not exposed to aerated fluid. The following shortlist should be considered for new and existing installations if aerated fluid is to be avoided.
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✦Significant or sudden pressure drop.
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✦Hydraulic shock as a result of sudden operation of valves and pumps.
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✦Inadequate operating conditions for various pump types.
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✦Inadequate diffusion of the fluid at the return tank.
In addition to effects on particle counts, aerated fluid can result in other problems of varying severity. These should be avoided where possible to keep personnel safe and maintenance costs low.
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✦Increased fluid temperature
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✦Reduced lubricity
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✦Cavitation and system component erosion.
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✦Noise
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✦Dampening and poor system control.
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The presence of solid contaminant particles in the liquid interferes with the ability of the hydraulic fluid to lubricate and causes wear to the components. The extent of contamination in the fluid has a direct bearing on the performance and reliability of the system and it is necessary to control solid contaminant particles to levels that are considered appropriate for the system concerned.
We have created a guide for you on classes of contamination, containing sampling procedures, reporting formats & code comparisons as well as other supporting information. Please click the image below for your free copy.
Condition Monitoring
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