Tunnel Pasteuriser Troubleshooting: Causes & Fixes

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Problems on this page:

Pasteurisation units (PU) out of spec Zone temperature drift Spray, pump or conveyor fault Broken bottles or burst cans in the tunnel Scale or spots on the containers Slime or odour in the spray water High water or energy use Containers leaving wet or too warm

Pasteurisation units (PU) out of spec

Hits OEE: Quality

Symptoms: PU low or high, under or over-processing, quality/safety risk.

Zone temperatures off

Calibrate and set zone temperatures; verify PU calculation.

Line speed or dwell wrong

Match conveyor speed to the validated PU.

Spray distribution uneven

Clean nozzles; ensure even water coverage.

Prevention: Temperature calibration, validated dwell, spray maintenance.

Zone temperature drift

Hits OEE: Quality

Symptoms: Zones drift from setpoint, inconsistent PU across the belt.

Heat exchanger or steam control fault

Service the heat exchanger; check steam/control valves.

Recirculation pump issue

Check zone recirculation pumps and flow.

Sensor calibration

Calibrate the temperature sensors.

Prevention: Heat-exchanger upkeep, pump checks, sensor calibration.

Spray, pump or conveyor fault

Hits OEE: Availability

Symptoms: Dry areas, low flow, belt stops or jams, throughput loss.

Blocked nozzles or strainers

Clean nozzles and strainers; treat water.

Pump or level fault

Check zone pumps and water levels.

Conveyor drive or tracking

Service the belt drive; correct tracking.

Prevention: Nozzle/water management, pump checks, conveyor maintenance.

Broken bottles or burst cans in the tunnel

Hits OEE: Quality

Symptoms: Broken glass or burst cans in the tunnel, product loss, stops for clean-up.

Temperature steps between zones too large

Set zone temperatures so each step stays within the container maker's limits.

Overfilled or over-carbonated product

Check fill levels and carbonation upstream.

Damaged containers entering

Inspect containers at the infeed.

Back pressure on the belt at the discharge

Reduce back pressure from the downstream conveyors.

Prevention: Breakage counted per shift and traced to its zone.

Scale or spots on the containers

Hits OEE: Quality

Symptoms: White spots or a film on cans, bottles or labels after the tunnel.

Water treatment dosing low or off

Check the dosing pumps and chemical levels.

Hard make-up water

Treat or soften the make-up water.

Spray water concentrating through evaporation

Manage the blowdown so the water is refreshed.

Fouled spray nozzles

Clean the nozzles and strainers.

Prevention: Spray water tested on a schedule.

Slime or odour in the spray water

Hits OEE: Quality

Symptoms: Slime in the tanks, bad smell, blocked nozzles, dirty containers.

Biocide dosing low or off

Check the dosing and the chemical stock.

Warm zones left with little water turnover

Clean and refresh the zone tanks on a schedule.

Spilled product feeding growth

Remove broken containers and clean after any breakage.

Prevention: Tank cleaning on a schedule and dosing checked every shift.

High water or energy use

Hits OEE: Performance

Symptoms: Steam and water use rise for the same output.

Heat recovery between zones not working

Check the regenerative pumps and valves.

Tanks overflowing continuously

Check the level controls.

Failed steam traps

Test and replace failed traps.

Make-up water valve passing

Repair the valve.

Prevention: Water and steam per unit tracked daily.

Containers leaving wet or too warm

Hits OEE: Quality

Symptoms: Containers exit wet or warm and labelling or packing downstream fails.

Cooling zone running warm

Check the cooling zone temperature and its heat exchanger.

Air knives after the tunnel not working

Check the blowers and the knife positions.

Line speed above design

Check the dwell time against the design.

Prevention: Exit temperature checked on the shift round.

Guidance only. Always follow lockout/tagout and your site's safe-work procedures, and verify against OEM manuals before acting.

Related equipment guides: autoclave · induction furnace · heat exchanger · evaporator · retort · can filler

Stop the same fault coming back

Recurring tunnel pasteuriser stops usually trace to a cause you cannot see by hand. The partner we recommend is Fabrico: it tracks OEE and downtime live from PLCs, IoT sensors or AI cameras; where cameras are fitted, the video of a stop sits next to its machine data so the cause can be reviewed; and a technician opens the work order from the stop in the same system. Data is hosted in the AWS EU region, and Fabrico and the company behind it hold ISO/IEC 27001, ISO/IEC 20000-1 and ISO 9001.

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Methods that cut recurring stops: the six big losses · root cause analysis · preventive vs predictive maintenance · TPM · SMED & changeover