Signs a scrubber needs attention

Most scrubbers decline slowly, so the symptoms are easy to live with until capture fails. The usual first sign is a rising pressure drop across the tower. Fouled or collapsed packing closes off the void space, the fan works harder against it, and the flow through the system falls away.

Rising pressure drop across the packed bed, or a fan that sounds like it is fighting the system
Liquor carry-over: droplets past the demister, wet ductwork downstream, or drip and staining at the stack
Falling capture at the hoods and slots, or operators reporting odour or mist at the bench
Visible corrosion, chalking, crazing or heat distortion on the shell, sump or supports
Sump fouling, sludge build-up, scale on the pump strainer, or a recirculation flow that has quietly dropped
Weeping joints, stressed nozzles, or movement at bracketry and plinth fixings

Where a thorough LEV examination has already identified defects in the scrubber, sump or associated extraction ductwork, we carry out the remedial fabrication that the report calls for. Beckox does the remedial fabrication work; we do not carry out statutory LEV examinations, so that side stays with whoever you use for testing.

What an inspection looks at

An inspection starts with the duty. Which process is being scrubbed, what the reagent is, what the liquor pH and make-up regime look like, and whether anything about the process has changed since the tower was installed. A scrubber sized for one chemistry rarely behaves well on another.

From there it is physical. Shell condition inside and out, weld lines and reinforcement, sump and internal supports, the state of the bed, the distributor, the mist eliminator, spray nozzles, pump and strainer, instrument tappings, and the transitions into ducting and stack. Free on-site consultations are part of how we work, and an honest look at the vessel usually settles the repair-or-replace question quickly.

Packing media replacement and repacking

Random packing does not last forever. Media degrades through chemical attack and UV exposure, fouls with particulate, salts and biological growth, and eventually deforms or collapses under its own weight and the pressure of the gas stream. Once that happens the bed channels: gas takes the path of least resistance, contact with the liquor drops, and removal efficiency falls even though the fan and pump appear to be running normally.

Repacking means draining and isolating the tower, removing the old media, cleaning the bed support and hold-down plates, checking the support grid for sag or damage, then charging fresh media of the correct type and size for the duty. It is worth confirming the media choice at the same time rather than replacing like for like out of habit — packing sizing follows the gas velocity and the tower diameter, not the previous order.

Spray distribution and liquor distributor cleaning

A packed bed only performs if the liquor arrives evenly across it. Blocked nozzles, part-blocked distributor holes, scale, and a distributor sitting out of level all produce dry patches in the bed. Those dry areas do no scrubbing at all, and the wet areas carry the whole load.

Distributor work covers strip-down and cleaning, clearing or renewing nozzles, checking the header for scale and internal debris, re-levelling, and confirming the recirculation flow and pump duty. Where the distributor or its pipework and controls have degraded past cleaning, we fabricate replacements in PP or PVC to suit the existing vessel.

Mist eliminator replacement

The demister is the last stage before the stack and the first thing to show when it is failing — carry-over, drips outside the building, and wet ductwork downstream. Eliminator media blinds with salts and solids, and it can also be crushed or displaced by a surge in flow. Cleaning is sometimes enough; often it is not, and replacement is the sensible call. See eliminators for how these are built and fitted.

Weld repairs and structural refurbishment

Thermoplastic vessels can be repaired properly. Cracked welds are gouged out and rewelded, damaged sections cut out and replaced, thin or attacked areas plated, and stiffening, legs, brackets and lifting points renewed where corrosion or vibration has taken them. Nozzles and flanges that have been over-stressed by badly supported pipework get re-made and, where needed, the pipe support arrangement gets corrected so the same crack does not come back.

The same techniques apply to sumps, catchpots and associated vessels — the approach is set out on our plastic tank repair page. Work is either carried out on site or the item is brought back to the Poole works, whichever suits the shutdown.

When refurbishment beats replacement, and when it does not

Refurbishment usually makes sense when the shell and sump are structurally sound and the problems are in the wear items: packing, demister, nozzles, distributor, pump, and localised weld damage. Those parts are consumable by nature, and renewing them can return a tower to proper duty without the disruption of new foundations, new duct routing and new connections, and we will set out the refurbishment and replacement costs side by side so you can compare them for your own vessel.

It stops making sense when the vessel itself has gone — widespread attack or embrittlement of the shell, heat distortion, repeated cracking in the same region, or a tower that was undersized or is now on a different chemistry from the one it was built for. In those cases we will say so and quote a replacement instead; there is nothing to gain from patching a vessel that is likely to fail again in the same way. New-build options are covered under fume scrubbers.

Planned shutdown work

Scrubber work is best done in a planned window. The tower has to come off line, be drained, flushed and isolated before anyone opens it, and the site permit system generally decides the sequence. Agreeing the scope in advance — what is being replaced, what is being inspected and decided on the day, and what materials need to be on the van — is what keeps the outage short.

Beckox has been fabricating and installing industrial thermoplastic equipment from its own Poole works since 1982, and refurbishment sits alongside new-build rather than apart from it: the same welders, the same materials, the same shop. To arrange a free site visit and an honest view on whether your scrubber is worth refurbishing, call 01202 736 725 or use the contact page.

PAGE REVIEWED — 30 July 2026

Fume Scrubber Refurbishment and Servicing