NEW-ISO-HV-150 (ND150)

Verify that the valve's set pressure does not exceed the tank rating (standard range: 1400-2100 mmAq for pressure, -350 to -700 mmAq for vacuum). Use pressure testing equipment to gradually increase system pressure and record the exact pressure at which the valve begins to open. Similarly, test vacuum side by slowly decreasing pressure and recording vacuum opening point. Both measurements must be documented and compared against manufacturer specifications.

Visually inspect all gaskets, O-rings, and seals for signs of wear, corrosion, cracks, or degradation. Check for any visible oil, gas, or liquid seepage around the valve body, disc interface, and connection points. For TANKTECH rupture pin models, verify zero leakage in normal state. Perform leak rate testing if necessary - acceptable leakage should not exceed valve specifications (typically <1 mL/min for cargo tank applications).

Inspect the flame screen/fire-blocking mesh (particularly critical for NEW-ISO-HV series with integrated fire-blocking technology) for physical damage, holes, corrosion, or blockages. Verify that mesh openings are not clogged with salt deposits, scale, or organic growth. For TANKTECH valves compliant with IMO MSC/Circ.677/1009, ensure flame passage prevention is intact. Clean with appropriate solvents if contaminated.

Conduct visual and dimensional inspection of the valve body for cracks, erosion, corrosion pitting, or structural deformation. Check all connection points (flange bolts, threads) for proper torque, missing fasteners, or corrosion. For stainless steel variants (SUS316/SUS316L), verify no surface degradation. For cast iron variants (FCD450), check for stress fractures. Measure flange PCD if applicable (e.g., ND300: 390mm with M16 bolts) and verify bolt integrity.

Verify that the visible disc operating position indicator (if present in U-ISO-H/V/G series) shows correct state (pressure and vacuum discs should move freely when hand-activated for testing). Check for any signs of disc sticking, jamming, or restricted movement. For NEW-ISO-HV rapid breathing models, ensure response time is within specifications during dynamic testing. Document any hesitation or sluggish behavior requiring maintenance.