TL;DR

Excessive overspray buildup in the dry scrubber reduces air flow and degrades paint quality. Follow the limestone powder charge schedule and replace the filter trays before build-up reduces booth airflow below specification.

What you might see

booth airflow below the specification on the manometer
paint film quality degrading with orange peel or contamination
filter tray pressure drop increasing above the replacement threshold
limestone powder usage rate below normal indicating blockage

Likely causes

Tap to mark as ruled out

Limestone powder charge rate set below specification for the paint throughput
Filter tray exchange interval exceeded allowing trays to saturate
High-humidity conditions reducing limestone powder effectiveness
Paint chemistry change increasing overspray adhesiveness to the dry scrubber media

Required tools

Replacement filter trays (Durr-specified)
Booth manometer or airflow meter
PPE for paint waste handling (gloves, respirator with organic vapor cartridge)
LOTO kit

Safety first

Lock out booth fans before accessing filter trays. Booth fan blades are close to the tray module access area.
Spent filter trays contain paint overspray waste that may be classified as hazardous. Wear gloves and respiratory protection and dispose per local hazardous waste regulations.
Paint spray environments may contain flammable solvents. Verify the booth is purged and solvent concentrations are below LEL before any hot work.

Procedure

6 steps · ~60 min

1
Check the current booth airflow measurement on the EcoDryScrubber control panel or booth manometer. Compare to the design airflow specification.[1]
2
Inspect the filter tray differential pressure indicator. Trays showing a pressure drop above the replacement threshold require exchange.[1]
3
Verify the limestone powder dose rate is set per the Durr specification for the current paint type and throughput.
4
Lock out the booth and recirculation fan before accessing the filter tray module.
Warning: Lock out booth ventilation fans before reaching into the filter tray module. Fan blades are exposed in some access configurations.
5
Remove and replace the saturated filter trays following the Durr tray exchange procedure. Dispose of spent trays per the paint waste disposal regulation.
6
After tray replacement, restore power, check airflow, and confirm it returns to the specification before resuming paint operations.

Sources

Dürr Dürr EcoDryScrubber / EcoBell3 Paint Spray Booth general technical documentation, Dürr
Durr EcoDryScrubber paint booth operator and maintenance documentation, dry scrubber media management (general)

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