I believe it makes pressure regulation easier. Pressure regulation works
by returning not needed flow (that is most of the forward flow) to the tank.
With pumps in parallel the second pump doubles the flow which requires
quick action from the regulator; also, the maximum pressure drop in the
return line (0.25 bar?) is easily exceeded . With pumps in series the
second pump does almost nothing (except double the maximum attainable
pressure at no flow condition - not relevant - and making it doubly
certain that the required flow is there).
Jan de Jong
On 11/6/2013 9:49 PM, William Daniell wrote:
>
> My manual from 2003 (J)shows the fuel pumps for a 914 in parallel.
> Does anyone know why the latest manual has pumps in series?
>
> Thanks
>
> Will
>
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