When a caustic packed scrubber removes H₂S but total sulfur remains high, identify COS, CS₂, mercaptans, and CO₂ rather than assuming the bed lacks surface area. Different sulfur species have different absorption and reaction behavior, so packing height, absorbent chemistry, reaction kinetics, temperature, and the analytical acceptance basis should be evaluated separately.

When a chilled-solvent VOC absorber underperforms, evaluate solvent temperature rise through the packed bed, gas sensible heat, heat of absorption, solvent circulation, chiller duty, solvent regeneration, and possible intercooling. Designing the entire bed at the inlet solvent temperature can overestimate the available absorption driving force.

When a vacuum degasser misses the dissolved-oxygen target despite clean packing, inspect air ingress through manways, flanges, seals, drains, and vacuum equipment. Total pressure alone may not reveal the problem if the vacuum pump compensates for leakage. Oxygen partial pressure, vacuum-system load, liquid distribution, water temperature, and analyzer accuracy should be reviewed together.

When surfactants enter a wastewater air stripper, stable foam can increase liquid holdup, raise pressure drop, reduce operating range, overload the demister, and disturb mass transfer. Water chemistry, upstream source control, airflow, packing openness, anti-foam effects, and pretreatment should be reviewed before replacing packing or increasing blower capacity.

When a scrubber meets its gas-removal target but the downstream fan corrodes, investigate mist carryover, demister velocity, wall bypass, drainage, packing entrainment, downstream condensation, and deposit chemistry. Gas-phase removal efficiency and liquid-droplet control are separate performance requirements.