When one of two parallel scrubbers is offline, common fans and headers can drive reverse gas flow through the idle tower unless suitable isolation is provided. Check pressure balance, damper leakage, flow direction, drainage, maintenance isolation, and restart condition rather than assuming a stopped pump or fan means zero flow.

When scrubber removal deteriorates while the pump still runs, check strainer or filter differential pressure, actual circulation flow, pump suction condition, and distributor pressure. A loaded strainer can reduce irrigation without producing a high tower pressure-drop alarm, while bypassing it can shift solids into the distributor.

When plastic packing shows localized thermal deformation downstream of a quench, investigate blocked nozzles, spray coverage, gas-flow maldistribution, and temperature mapping. One hot gas stripe can damage a section of the bed even when the average measured outlet temperature remains within the polymer's normal operating range.

When chlorine breakthrough occurs despite normal hydraulic operation, verify caustic inventory, pH measurement, dosing response, liquid mixing, and possible chemical contamination before increasing packing. Chlorine scrubbing depends on maintaining the intended alkaline chemistry throughout the full design event.

Paint and resin overspray can coat packing with a sticky film that captures more dust and droplets, progressively increasing pressure drop and reducing wetting. Upstream overspray capture, coating chemistry, packing openness, cleaning access, and deposit behavior should be evaluated before selecting fine high-area packing.