The Shell V50 equation is exactly as you say. It is intended for fuel oils with a reference temperature of 50[°]C but in practise there are often problems.
An alternative approach is to use the multi-curve method.
This is used in process viscosity measurement where only one viscometer, measuring at one temperature, is used.
There are some precautions necessary when using it.
For example, in the refinery and when the ISO 8217 reference temperature was 100[°]C, you could install a single viscometer in the line measuring at anywhere between 90[°]and 130[°]C and get very good results for the viscosity at 100[°]C
With the change to 50[°]C, the method is not safe because of thee differential between measurement temperature and reference temperature and because thee reference temperature is in a region where the viscosity temperature gradient is comparatively steep.
On the other hand, during bunkering, where the measurement temperature is usually between 40 and 60[°]C the method again works very well.
Note that the Shell V50 was intended for this type of application.
In several instances where I have seen it used during bunkering the results left a great deal to be desired, perhaps because the users entered thee wrong factors?
The multi-curve method depends on using a number of reference curves and in many applications even the CIMAC data from way back seems to work well.
However, it is recommended to collect more upto date reference curves from lab analyses whenever the opportunity presents. The more representative the curves, the more freedom in the measurement temperature.
Visit
for a spreadsheet for viscosity Vs Temperature. If you follow the contact link and send an email a spreadsheet for multi-curve is also available from RMI. These sheets use the ASTM D341 expession for the temperature Vs Viscosity.
For your interest, there are two FAQs on process viscosity measurement which touch on this, you can get to both in the FAQ in this forum (click FAQ on the menu bar at the top of the page).
JMW
