My oiler

[BobL]

I've done the experiment.
The bar oil is conventional bar oil with an extra shot of tackifier put in for me by my oil supplier.

I measured the flow (in g/min) at different pressures (head or height) of the oil column.

I used a length of PVC pipe with an end cap and small irrigation fitting tap glued into the middle.
The flow rate is low, about 1/2 to 1/3rd of a normal aux oiler flow rate but I did that deliberately to really see if an effect was present.

If the oil was newtonian and the flow rate at the start was 6.8g/min the flow rate should follow the red line i.e. drop in direct proportion to the head but instead it follows the blue triangles.
This means this bar oil is newtonian.

Its a bit counter intuitive because it seems like oil flow is not falling as fast as it should, but what it really means is that the flow rates at higher head or pressures are less than they would be because the viscosity has been affected by the higher pressure.

What does it mean - it means the aux oil flow rate does change with head or height but not in direct proportion but about 30% less than it would if it was a newtonian fluid.

So thats a good thing.



When I get time I'll do the test again with another oil.

 

[PhilB]

Flow to head isn't a linear function but flow increases as the square root of the head. i.e, the flow would double if the head was increased four times. Using Bob's experiment: as the head is halved from 30 to 15 cm head, one / the square root of two (0.707) times 6.8 gpm equals 4.8 gpm. Close to Bob's 5 gpm at 15 cm of head.

 

[BobL]

Thanks Phil, I forgot about Torricelli's Law.
Here's the comparison between the Bar oil flow (Blue triangles) and theory (Red squares).
If there is any non-newtonian effect it is too small to determine.





Either way its good for oilers not to lose too much flow with the loss oil level height,.

 

[kjudd]

thanks for doing the experiment BobL That would explain why I did notice much change in flow with my 6ish inch (15cm) of drop. It looks like it changes roughly 2 g/min over that distance.

 

[Pauls_Workshop]

Thanks Phil, I forgot about Torricelli's Law.
Here's the comparison between the Bar oil flow (Blue triangles) and theory (Red squares).
If there is any non-newtonian effect it is too small to determine.

View attachment 509746



Either way its good for oilers not to lose too much flow with the loss oil level height,.

Thanks for all this effort Bob. Great experiment! It turned out very close to what I was saying and expecting earlier. The tackifyer/additives has a very very small effect related to pressure or head. - Paul