how to explain that kinematic viscosity of air is greater than water

Your quoted kinematic viscosity number is in fact million times smaller as is indicated in the column of the table you used. According to the data in the table you are referring to, I see that the kinematic viscosity of air at atmospheric pressure is 16.97 x 10-6 cSt at 40 deg C, and 18.90 x 10-6 cSt at 60 deg C. At 50 deg. C, kinematic viscosity would be somewhere in between 40 and 60 deg C. I hope this helps put to rest your dilemma.

Dear Mr. John, thanks for your response.

in fact the value of Kinematic viscosity at 40 °C is 16.97 x 10-6 m2/S.

the conversion to centistokes is:

16.97 x 10-6 m2/s*(1000 mm/1m)^2 =16.97 mm^2/s= 16.97 cSt.


that is very confused to me.

regards!

Dear AngeLube, I stand corrected. Your calcs are correct. I overlooked the fact that the table shows data in m2/s units..

I am not sure there could, other than for a pure theoretical/scientific purposes, be possible to make any relation to practical tribology. However, I think that the molecular sizes, density, surface tention and wetting characteristics of each media would affect particle motion through them.