What products are involved?
RPS Rheonics Process Systems: InkSight, SlurryTrack, PaintTrack
What is the purpose of this article?
To explain how engineering units behave in the RPS System Screen and when the Cup Seconds Conversion function is working


1. Which viscosity units are available on RPS System?

Rheonics RPS software can display 3 different units for viscosity: mPa.s, cP and Seconds (s). The first two units are equivalent and will show the direct viscosity measurement from Rheonics sensor. The Seconds Unit is used for a Rheonics to Viscosity Cup conversion feature. This is useful to compare the Rheonics sensor readings with Viscosity Cups e.g. Zahn cups.

Real-time viscosity measurements can be visualized from the Control tab (Tab name can change depending on RPS System). Measurement units are not displayed in this Tab, just the values. 

Figure 1. Color control tab Inksight software


2. Selecting the viscosity unit

Follow next steps to select the viscosity unit in the RPS System. This viscosity value will ultimately be saved in the measurement reports.

  1. Go to the Settings Tab.

  2. Select the required units of viscosity.


Figure 2. Viscosity unit selection.

3. If the selected value is cP or mPa.s then the viscosity value shown in Control Tab will be the direct output form the Rheonics sensor. Consider that cP and mPa.s are equivalent units (1 to 1 relation).

4. In case you switch the viscosity units to Seconds as shown in Figure 3, then the cup-seconds conversion coefficients A1 and A0 will be used to calculate a cup-seconds equivalent for the Rheonics sensor measurement.


How does viscosity readings of Rheonics sensors correlate to viscosity cups readings?

There is not a direct relation that will hold true for all fluids between Rheonics sensors and an specific Viscosity measuring cup. Consider that most real application fluids are Non-Newtonian, which means that the viscosity reading will be dependent on shear rate at which is measured. 
Clients can evaluate whether there is a suitable correlation between inline viscosity readings and manual cup measurements. This is usually done by registering both instrument measurements and compare them in a table. Coeffiecients A0 and A1 are obtained from this.
Read more on this topic here.


Figure 3. Cup-seconds conversion coefficients. 


Rheonics pre calculated coefficients

You can import from a list of pre-calculated coefficients for different units or calculate your own as indicated in this article Converting inline viscosity measurement to equivalent cup seconds  These values will not hold true for all fluids and it is recommended that clients verify the correctness of coefficients by testing with the fluid of interest.

5. You can input your custom values in the Settings. For example, if A1= 0.36 and A0=11, you can write the values directly in the coefficients box as shown next.

Figure 4. A1 coefficients for the cup-second conversion input on the software.

Figure 5. A0 coefficients for the cup-second conversion on the software.

And that's all. By writing these A0 and A1 values, and having the units selected as cup-seconds, the Control Tab will now show the cup-second equivalent for your cup.

Figure 6. Calculated values for cup-second conversion.


For further information review Rheonics RPS Manual or contact Support Team at [email protected]



References

1. https://rheonics.com/products/rps-inksight-rheonics-printing-solution/

2. https://rheonics.com/slurrytrack/