Ultrafiltration Unit Troubleshooting: Causes & Fixes

Not your exact symptom?

Describe it in the symptom finder and search the whole directory.

Problems on this page:

Permeate flux falling Retentate concentration off target Membrane integrity failure Cleaning not restoring performance High pressure drop across the modules Microbial counts rising in the product Circulation pump faults Diafiltration water use too high

Permeate flux falling

Hits OEE: Performance

Symptoms: The unit produces less permeate at the same pressure, and batches take longer.

Membranes fouled with protein, fat or minerals

Run the cleaning sequence the membrane supplier specifies, and check it reaches the right temperature and concentration.

Feed temperature lower than the design

Check the feed heat exchanger; colder feed is more viscous and lowers flux.

Cross-flow velocity too low

Check the circulation pump output and the pressure drop along the modules.

Membranes at the end of their life

Compare clean-water flux after cleaning with the value when the membranes were new.

Prevention: Clean-water flux recorded after every clean so membrane condition can be trended.

Retentate concentration off target

Hits OEE: Quality

Symptoms: The concentrate leaving the unit is too thin or too thick for the next step.

Concentration factor setting wrong

Check the volume concentration setting against the product specification.

Flow meter on permeate or retentate drifting

Check the flow meters against a timed volume.

Feed composition changed

Check the solids of the incoming feed.

Control valve on the retentate sticking

Service the valve and its positioner.

Prevention: Retentate solids checked by the lab each batch.

Membrane integrity failure

Hits OEE: Quality

Symptoms: Protein or other retained components show up in the permeate.

Membrane damaged by pressure or temperature

Check the operating limits were not exceeded and inspect the modules.

O-ring or seal leaking in a housing

Find the leaking module by sampling permeate from each housing, then replace its seals.

Chemical attack from cleaning outside limits

Check cleaning chemical concentration and temperature against the membrane limits.

Back pressure on the permeate side

Check the permeate line for closed valves during operation.

Prevention: Permeate quality tested each batch.

Cleaning not restoring performance

Hits OEE: Availability

Symptoms: Flux stays low after cleaning, and the unit needs repeat cleans.

Cleaning temperature or concentration too low

Measure the cleaning solution during the cycle, not only at make-up.

Cleaning time too short

Check each step runs for its full time.

Wrong cleaning sequence for the soil

Agree the alkali, acid and enzyme steps with the membrane supplier for your product.

Rinse water hardness too high

Check the quality of the water used to make up and rinse.

Prevention: Cleaning parameters logged for every clean.

High pressure drop across the modules

Hits OEE: Availability

Symptoms: Inlet pressure climbs and the unit alarms or slows.

Feed channels blocked by particles

Check the pre-filter or strainer ahead of the unit.

Product too concentrated for the module type

Check the concentration against the module design.

Fouling not removed by cleaning

Review the cleaning sequence with the supplier.

Pump speed set too high

Check the pump speed against the design.

Prevention: Pressure drop trended per stage.

Microbial counts rising in the product

Hits OEE: Quality

Symptoms: Lab results show higher counts in the retentate or permeate.

Process temperature in a growth range for too long

Check the batch time and the temperature control.

Cleaning and sanitising incomplete

Check the sanitising step and its contact time.

Dead legs in the pipework

Find dead legs where product sits and remove them.

Membranes stored without preservative

Store idle membranes in the solution the supplier specifies.

Prevention: Microbial results reviewed per batch.

Circulation pump faults

Hits OEE: Availability

Symptoms: The high-flow circulation pump trips, leaks or gets noisy.

Mechanical seal leaking

Replace the seal and check the flush to it.

Cavitation from low suction pressure

Check the feed tank level and the feed pump.

Bearing wear

Check bearing temperature and vibration.

Motor overload from high viscosity

Check the product concentration and temperature.

Prevention: Pump vibration and seal condition checked on a route.

Diafiltration water use too high

Hits OEE: Performance

Symptoms: The unit uses more water per batch than planned.

Diafiltration volume set too high

Check the setting against the product specification.

Flow meter error

Check the water flow meter.

Extra rinses added by habit

Compare the running sequence with the approved one.

Leaking valves passing water

Check the valves on the water line for leaks.

Prevention: Water use per batch recorded.

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

Related equipment guides: reverse osmosis system · centrifugal pump · CIP system · heat exchanger · homogeniser

Stop the same fault coming back

Recurring ultrafiltration unit 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.

Book a Fabrico demo

The directory stays free.

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