Fouling is the build-up of unwanted material on heat-transfer surfaces. In a plate heat exchanger, where the flow channels are narrow and the plates are thin, even a small amount has a noticeable effect.
Two effects at once
First, a layer of deposit acts as insulation, so less heat passes through the plate. Second, it narrows the channel, so more pressure is needed to maintain the same flow. The result is lower outlet temperatures and higher pumping energy — often long before anything leaks.
Common types of fouling
- Scale — mineral deposits from hard water, especially on hotter surfaces
- Biological growth — slime and marine growth in cooling and seawater
- Particulate — silt, rust and solids carried in the flow
- Product fouling — proteins, sugars and other residues in food processing
- Corrosion products — from pipework or the plates themselves
Monitoring fouling
The simplest indicator is pressure drop across each side of the unit. Logging it alongside inlet and outlet temperatures gives an early warning that performance is falling and lets you plan cleaning before it becomes urgent.
Managing it
- Keep velocities up — oversized units can foul faster at low flow
- Use strainers where solids are present
- Consider clean-in-place for predictable, light fouling
- Schedule workshop cleaning when CIP no longer restores performance
Seeing rising pressure drop? Request a quote or call (02) 9897 7371.