Detecting foam or ignoring foam: define the objective

Wet foam and dry foam are different states

Foam contains gas and liquid in changing proportions. Its response at a sensing tip can vary with drainage time, product concentration, bubble structure and contamination. A setting that separates one sample from liquid may not separate every foam condition.

State explicitly whether foam should count as covered. For overflow management, detecting foam can be useful; for a pump permissive, foam without a dependable liquid supply may be unsuitable.

A useful test matrix

Record clean air, process liquid, fresh foam, drained foam and residual film after emptying. Repeat the sequence at relevant temperatures and with the actual mounting arrangement. Where the device supports parameterization, retain the settings and evidence of separation between states.

Avoid an artificial pass

A test that wipes the tip clean before every empty reading may miss the real problem. Let the sensor drain naturally, using the expected cycle time. If the liquid and unwanted foam responses overlap too much, a different sensing location, process change or sensing method may be necessary.

What to confirm for your application

• Should foam be detected or ignored?
• Foam age and wetness
• Post-drain residue
• Temperature and formulation range
• Acceptable transition time