We are facing problem with the calibration of the displacer type level trol supplied by Fisher model: 249 side mounted in a cage with DVC controller. The service is crude oil and density around 0.8. We are using it in a separator for both oil level as well as another for interface level. Whenever we calibrate with water on either case it is not accepting the span and comes out of the calibration mode. Pls do help us with the right procedure.

 

If the level trol was originally designed/calibrated for oil having a density of 0.8, you cannot use water with a density of 1.0 to re-calibrate it. When you are using water, and trying to set the span value, you are effectively pushing the displacer well beyond its intended span position. The denser water will float the displacer with less 'sinking' (water displacement) than when using oil. Get hold of a 'can' of clean oil with a density of 0.8 and redo the calibration.