Wet Film Thickness Testing (WFTT)

Regular WFTT measurements, used alongside visual inspection and cleaning, support fire risk management, help establish cleaning frequencies, and demonstrate compliance with TR19® Grease standards. Insurance claims may not be settled if systems are found to be the cause of fire and have not been regularly maintained in accordance with TR19® Grease requirements.

What is WFTT?

WFTT measures the thickness of deposits at representative points within an extract system. This testing provides an objective, repeatable and quantifiable method of assessing grease and soft-deposit build-up – overcoming the limitations of visual inspection alone.

Recording WFTT measurements before and after cleaning provides quantifiable evidence of:

• Pre-clean system condition and deposit levels
• Cleaning effectiveness and deposit removal
• Post-clean compliance status

These measurements are recorded as part of the Post Clean Verification Report (PCVR) and support evidence-based decisions about future cleaning intervals and ongoing compliance with TR19® Grease standards.

When is WFTT useful?

WFTT can be used during initial surveys, before and after cleaning, and as part of an ongoing maintenance programme. Pre- and post-clean measurements are particularly valuable because they:

• Verify cleaning effectiveness – show quantifiable deposit removal
• Document compliance – provide evidence for PCVR and audit purposes
• Establish baseline data – help determine appropriate future cleaning intervals
• Support risk-based scheduling – allow intervals to be tailored to actual deposit accumulation rates

Results should be considered alongside system use, cooking activity, operational hours, cuisine type, access, visual condition and other relevant risk factors when setting future cleaning intervals. Many systems will require cleaning more frequently than the minimum annual basis, depending on these factors.