Flow monitoring conversion

[ldwilliams.uk]

Hi, I am looking to get the Alphacool ES flow and temperature indicator "HighFlow" with RPM-Signal         
https://shop.alphacool.com/en/shop/controllers-and-sensors/flow-sensor/17558-alphacool-es-flow-and-temperature-indicator-highflow-with-rpm-signal

 

It has a conversion table for RPM to litres per hour which should be simple enough I would have thought, but the conversion ratio looks to change for each rpm given?

How do I create an offset (think thats what is needed) and what would the offest be please anyone?

Thanks

[ldwilliams.uk]

I think that the ratio is 0.18 and the offset is -10 ?

[ldwilliams.uk]

 

This bring results of

Actual l/hr           Reported l/hr

40	48.86
50	56.42
60	62.72
70	70.82
80	78.74
90	81.8
100	90.8
110	105.2
120	116
130	122.66
140	130.94
150	143
160	162.8
170	176.12
180	181.52
190	189.8
200	204.56
210	211.04
220	219.5
230	227.96
240	241.64
250	247.4
260	255.86
270	270.8
280	279.44
290	285.2
300	293.3