BOLLFILTER Automatic Type 6.21/6.22

Check differential pressure indicator reading against manufacturer-specified maximum allowable differential pressure (typically triggers at 0.5–1.0 bar); replace or clean filter elements if exceeded.

Inspect and test the automatic backflushing / changeover mechanism (motorised valve, turbine drive, or compressed-air solenoid) for correct actuation, timing, and completeness of backflush cycle.

Verify integrity and cleanliness of filter elements (wire-mesh candles, star-pleated elements, or basket strainers): inspect for holes, deformation, blinding, or corrosion; replace per manufacturer interval.

Check all seals, O-rings, and gaskets on filter heads, element seats, and drain valves for leaks, hardening, or extrusion; renew if any fuel oil weepage is detected.

Inspect and clean drain valve(s) and flush / drain lines; confirm that backflush discharge lines are clear and not blocked by residues or solidified heavy fuel oil.

Verify correct operation of the duplex changeover valve (plug, ball, or damper type): smooth actuation under pressure, no internal bypass leakage past valve seals to the stand-by chamber.

Check heating medium circuit (steam or thermal oil jacket) for correct temperature (HFO systems: 80–100 °C supply, 130–160 °C booster), circulation flow, and absence of leaks.

Confirm classification-society-required maintenance records (e.g., IACS, DNV, BV, LR) are up to date; verify that any pressure-vessel inspection certificates for the filter housing are valid and that safety relief valves on by-pass circuits are tested.