NSLH

Inspect mechanical shaft seal for visible leaks; check seal seat for flatness, cracks, and rubber parts for elasticity loss; measure clearance in seal chamber (typical max 0.4-0.5 mm radius)

Remove and visually inspect impeller for cavitation erosion, wear ring thickness, and dimensional changes; check exchangeable wear plates for scoring or material loss; verify impeller clearances meet specification

Monitor for cavitation noise during operation; inspect impeller inlet surfaces for pitting and erosion patterns; verify suction conditions meet NPSHreq at operating point; check inlet pressure exceeds NPSH requirement

Replace all sealing rubber rings during pump overhaul; inspect bearing clearances; verify bearing housing bolts for tightness; check for discoloration or hardening of rubber components indicating age/heat damage

For Modular S/SA/NSA: verify diffuser passages are clear and not clogged; check priming valve/check valve operation; inspect wear plate for cracks affecting diffuser principle function; test air-liquid mixture handling capability