High Pressure Duplex Filter HPDF Series (HPDF-30 to HPDF-660)

Check differential pressure indicator/gauge reading at inlet and outlet — replace or clean filter element/basket when differential pressure reaches the manufacturer-specified threshold (typically 0.35–0.5 MPa for duplex units).

Inspect changeover (three-way diverter) valve for smooth, leak-free operation and verify standby chamber is fully pressurized and ready before switching over.

Examine filter element or strainer basket for mechanical damage, corrosion, or deformation; clean or replace per maintenance schedule or when differential pressure triggers the bypass valve.

Verify automatic backwash or self-cleaning cycle (where applicable): confirm controller triggers, backwash drain valve opens/closes correctly, and backwash water consumption remains below specified limit.

Check all seals, O-rings, and gaskets on filter bowls, vent plugs, and drain plugs for leakage, swelling, or embrittlement, especially after contact with fuel oil.

Inspect bypass valve function: confirm it does not open prematurely under normal operating pressure and does open at set pressure to protect downstream components.

Verify that vent/bleed plugs and drain plugs are correctly torqued and not leaking; check clean-side and dirty-side drain lines for blockages.

Confirm electrical connections, solenoid valves, and differential pressure switches (for automatic/motorized units) are properly wired, functional, and protected from fuel oil ingress.