Automatic backflush filters are intended to safeguard engines by maintaining clean fuel and lubricating oil, however, the recent claims indicate that when they malfunction, they can instead become a significant cause of engine damage.
Automatic backflush filters are widely used in fuel and lubricating oil systems to continuously remove contaminants using fine wire mesh candles. Unlike traditional filters, they clean themselves through a pressure-triggered backflush process that allows uninterrupted engine operation by switching between filter chambers.
However, failures have been reported where the fine mesh disintegrates during use, allowing metal fragments to enter the lubrication system and cause severe damage to engine bearings.
Differential pressure concerns
Pressure-triggered rinsing cycles are an inherent risk. If the filter candle mesh start disintegrating, the mesh becomes riddled with holes. With enough ruptures, the differential pressure drops, as the oil will follow the easiest route through the mesh. This will lead to a free flow through the housing, with oil potentially carrying wire mesh parts directly into the engine.
The damages
The small wires of the mesh break off and can travel through the entire lubrication system, causing severe damage. This damage will be primarily located on bearing surfaces on camshafts and crankshafts. This will in turn create severe surface deterioration and breakdown that can damage the engine even further and lead to dangerous situations. Replacement of main bearings and even the crankshaft itself can be very expensive and time consuming.
How to avoid serious incidents
Depending on the make and type of the filters, maintenance requirements will differ. In the matters seen by Gard, disintegration is either due to mechanical damages from rough handling by the crew or old candles having suffered excessive rinsing cycles and use beyond the expected lifetime.
The lifetime is determined by shelf-life storage conditions, rinsing cycles and handling, the Club highlights.
Gard recommendations:
To maintain backflush filters and prevent damage due to deterioration:
- Ensure the correct manual and procedures for the actual filter system installed are available onboard the vessel and that the crew have been adequately familiarised and trained.
- To ensure safe operation of the backflush filters, procedures on manual handling addeherent to makers recommendations should be in place, together with clear procedures on when filters are to be taken out of use due to damage and risk of failure.
- The engine crew should be trained to spot even minor damage to the candles. Training on how to handle the filters with care during cleaning is vital. We recommend having cleaning tools onboard like an ultrasonic cleaner unit or cleaning gun which blows horizontally onboard,
- If not already installed, a strainer or in-line filter should be installed after the backflush filter to ensure debris from candle disintegration is captured before it contaminates the oil system.
Use OEM parts. If in doubt, contact your filter manufacturer for advice