hydraulic filter clog

Monitoring Filter Condition

Let’s change gears and discuss the benefits of monitoring the condition of your hydraulic filter elements.

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Warning of filter-bypass is typically afforded by visual or electric clogging-indicators. These devices indicate when pressure drop (delta P) across the element is approaching the opening pressure of the bypass valve (where fitted).
 
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In the case of a return filter for example, if the bypass opens at a delta P of 3 Bar, the clogging indicator will typically switch at 2 Bar.
 
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Replacing standard clogging-indicators with differential pressure gauges or transducers enables continuous monitoring of the filter element.
 
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Think of it in terms of the engine coolant temperature on your car or truck. Would you prefer to have a gauge on the dashboard that allows you to monitor coolant temperature continuously or a light which only glow when the engine has already overheated?
 
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Similarly, continuous monitoring of the filter elements in a hydraulic system can provide valuable clues to the performance of the filter and the condition of the system.
 
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This allows trending of fluid cleanliness against filter pressure-drop, which may be used to optimize oil sample and filter change intervals. For example, the optimal change for a return filter in a particular system could be higher or lower than switching pressure of the clogging indicator.
 
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Continuous monitoring may also provide early warning of component failures and element rupture. For example, if the delta P across a pressure filter suddenly increased from 1 to 3 Bar (all other things equal), this could be an indication of an imminent failure of a component upstream.
 
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Similarly, a sudden decrease in delta P could indicate a rupture in the element – something a clogging indicator will never alert you to.

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Craig Cook

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