Try to use a DVC digital controller (I/P) from Fisher. You can then configure this controller to 'quick opening' which should make the response to become linear.
We currently have a 2-in level control valve installed on the test separator water outlet going to the Hydrocyclone unit. This valve currently can only flows about 8000 bwpd @ 1 bar dP. With another well coming on line and by lowering the separator pressure down to acceptable limit, we...