I am interested to hear from people's opinion from the oil industry, or any company who performs QC check with kinematic viscosity. We got a CANNON kinematic viscometer in lab. It seems to be a common practice here for everything with a control chart. But our kinematic viscosity measurement frequency is quite low. To generate a control chart with plenty data point to give upper/lower limits, it needs some additional runs with the CANNON standard. We end up doing 40 runs simply to get a control chart. But the actual test is 1 or 2 samples per season. We will need to start another control chart whenever the standard oil is running low (using new oil), or we did a tube calibration, or standard oil expired... I feel like a calibration check with standard oil would be enough to verify the machine in good shape. But I am wondering what is the common practice for oil industry who does viscosity more often to verify their process? Do you guys do control chart?
What do you mean by "40 runs simply to get a control chart"?
Did you vary the temperature or just doing a kind a statistical analysis?
If you vary T, a reduced number of runs is very likely enough.
Philippe, thanks a lot for your response. Actually, someone asked for 20 repeat runs at each temperature as we have two temperature level for our test. It is simply for the statistic, mainly control chart, which I believe is not valid as 20 repeat in a short time duration will not reflect long term behavior. So I am curious to know that others are doing for their QC check of kinematic test.
I better understand your question.
In fact, we do not do QC tests because we are an academic research lab, our fluids are stable at the scale of our studies, and we use rotary rheometers.
When it is critical, we repeat the µ=f(T) curves 3 times, but this remains quite unusual.
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