REFLECTOR: Oil Coolers

[Jim Sower]

<...(ignoring the pressure relief bypass in the  engine) ...>
But you can't rationally ignore it.



Al Gietzen wrote:

>I don't understand the difference in pressure that one oil cooler would see 
>versus two oil coolers in series???
>
>Ronnie
>
>I may not understand the question; but oil pumps are basically positive
>displacement, so will pump a certain flow for a given rpm, regardless of the
>pressure it's pushing against (ignoring the pressure relief bypass in the
>engine).  So if one cooler has a 20 psi drop across it, then two in series
>will have 40 psi drop (plus some fitting losses), so the first cooler in
>series now sees 20 psi higher pressure.  With cold oil the pressure drops
>could be high.
>
>However; I think every engine, certainly the aircraft engines, has an
>internal bypass relief valve downstream from the pump which will bypass the
>coolers if the back pressure is too high.  Whether the cooler is subject to
>damage depends on the design pressure of the cooler, and the adjustment of
>the bypass pressure.
>
>Al
>
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