The flow sensors measurement quality highly depends of the capillary surface cleanliness. Therefore, deposits on the capillary wall can lead to a measurement deviation and/or an offset.

Cleaning flow sensors with DI water after use when using water based solutions ensures their longevity and measurement quality. 

But sometimes it is not enough and advanced cleaning using a cleaning solution can help. A cleaning protocol using Hellmanex solution is described in the MFS User Guide.