The vibration puck that only lies in the afternoon
A citrus packing house near the ridge asked us to look at a compressor that ‘vibrated more after lunch’. The morning trend from their local folder was a flat line. The afternoon trend looked like a truck driving over the skid.
The bearing housing was cool to a reference probe. The vibration puck, though, sat on a black painted plate in full sun after 13:00. Its plastic shell was soft. The adhesive pad had crept a few millimetres toward the edge of the housing, which is enough to turn a clean reading into a chatter of the puck’s own case.
We moved the puck to the shaded rib the manufacturer actually draws in the mounting note, waited through another afternoon, and the wild trace disappeared. Nobody changed a bearing. Nobody ‘optimised a workflow’. The lesson was smaller: outdoor vibration sensors need shade or a metal standoff, and a single morning snapshot is not a health record.
If you keep readings in a local tracking folder, tag the file with weather and sun angle for rooftop kit. Afternoon lies are common. They are also cheap to catch if someone is willing to stand on the roof at 15:00.