REFLECTOR: Franklin Oil temp and flow data

[John Dibble]

On 11/14/2013 1:29 PM, Laurence Coen wrote:
> Brian,
> There are two valves in the "bypass plate" and they perform 
> independent functions.  The pressure regulator valve sets the oil pump 
> pressure at 80PSI.  That is the maximum pressure that can exists 
> anywhere in the system and is also the maximum pressure that the oil 
> cooler can see.
Well, with the 80 psig spring in the cooler bypass location, at start up 
on  cold days I would see 99 psig at the cooler outlet (99 is the max 
reading for my RMI monitor, so it could have been higher).  Seems like 
the pressure going to the cooler would have been higher yet.

John

>   Please note that this has nothing to do with the external loop 
> bypass valve.  Your data would indicate that your statement that no 
> oil flowed for nine minutes is incorrect.  I don't how you are 
> measuring oil flow or where but the fact that there is a differential 
> pressure at the output of the oil cooler and the galley is only 
> possible if there is flow through the cooler.  In a hydrostatic system 
> (no flow) where two points are connected the pressure will be the 
> same.  Your graph shows a differential pressure at opposite ends of a 
> tube connecting the oil cooler and the oil galley.  This indicates oil 
> flow through the cooler from start up to shut down.
> Functionally, the Franklin set up works the same as the pressure 
> regulator/"Vernatherm" in a Lycoming.  In a Lycoming, when the oil is 
> cold, The Vernatherm opens a bypass on the oil cooler loop.  When the 
> oil gets hot the Vernatherm closes the bypass forcing the oil to flow 
> through the oil cooler.  On the Franklin the fact that cold oil is 
> thick when cold causes a large drop in pressure through the external 
> loop. This in turn opens the bypass just like the Vernatherm on the 
> Lycoming.  When the oil is hot, the pressure drop in the external loop 
> decreases allowing the bypass to close, just like the Vernatherm did 
> in the Lycoming.  In both cases the pressure regulator simply sets the 
> output pressure of the oil pump.
>

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