Saybolt Viscosity test

[singkt]

I recently tested MC - 70 (Medium curing cutback) using saybolt viscometer. I got a result of efflux time of 50 sec @ 50 oC temp.; while the Specification says 60-120 sec.

Using a conversion table of Furol to kinematic viscosity; the 50 sec is approximately equal to 105 Centistokes and for MC - 70, the required kinematic viscosity is between 70 to 140.

I am now in doubt to accept or reject the material. Any idea please?

 

[SMF1964]

A quick Google turned up a table of kinematic viscosity and equivalent Saybolt 122°F and 212°F numbers (

http://www.westerndynamics.com/Download/kinsayfurvisc.pdf)

and a Saybolt of 50 at 122°F (50°C) is a little bit above 100 cSt kinematic viscosity - I would assume that this kinematic viscosity is at 50°C.

Most of the lube oil product literature we receive uses data generated at 40°C and 100°C and for this reason, our viscosity baths are at 40 and 100 degrees. My question to you is whether the 70-140 range you have is based on 40°C or 50°C (122°F)? If you didn't adjust for the different temperatures, then you have only the Saybolt data to base your accept/reject call on and you might as well reject the oil.


Did you try running a kinematic viscosity directly?

 

[singkt]

SMF1964, Thank you,

SMF1964, actually I am doing a test on cutback bitumen (I think cutback bitumen is no more in use in USA and other countries). For cutback bitumen we test Saybolt viscosity at 50°C and Kinematic viscosity at 60°C (in our case) or at 135°C. The 70-140 cSt is for kinematic viscosity at 60°C.

Yes, I indeed run a kinematic viscosity test later, for making conclusion, as it is recommended by AASHTO that viscosity indexes be derived from kinematic viscometer than saybolt viscometer. At the time, I asked because I didn’t have the kinematic viscometer in the project site laboratory.

We also modified the MC-70 bitumen to get an efflux time between 60 – 120 sec of the Saybolt viscosity and we got also the right kinematic viscosity.