6.33 Automatic Backflush Filter

Check differential pressure across each filter element (working and standby) against the manufacturer's rated maximum; differential pressure exceeding alarm setpoint requires cleaning or element replacement

Inspect changeover valve (three-way cock) for smooth operation and absence of leaks; confirm the valve fully seals the standby chamber and allows no cross-contamination

Examine filter elements (candle or mesh type) for mechanical damage, deformation, corrosion or blockage; clean or replace at specified intervals or when pressure differential indicates fouling

Verify heating system integrity (steam or hot-oil heating coil/chamber): check for leaks, adequate heat supply, and correct temperature of the filtered heavy fuel oil

Test the automatic backflush or switching mechanism under load: confirm the automatic cycle initiates at the correct differential pressure setpoint and completes without interruption to the fuel supply

Inspect all seals, gaskets and O-rings on element housings, end caps, drain valves and changeover valves for deterioration, cracking or fuel oil leakage

Check drain/blow-off valves for correct operation: they must open during backflush/cleaning and close fully afterwards to prevent by-pass of unfiltered fuel

Review and test the differential pressure alarm and clogging indicator: confirm correct calibration, electrical/pneumatic signal transmission to the alarm panel, and response at rated setpoint