Trying to determine the inlet pressure to a throttle valve.  The information I have is:
Is there any way that can calculate the upstream pressure or the pressure drop across the valve from this information?  I have sent all this to the valve manufacturer for them to run through their program but was wondering if a manual calculation is do-able.
Remeber that with a control valve you have one degree of freedom and you must either select your CV (degree of opening) or your downstream pressure.
It would be most common to have you pressure chosen and then calculate the Cv.
If you size the valve - calculate Cv for you normal flow case, up pressure and down pressure (this may require some brain activity since what is "normal/worst normal etc case"). Choose a mid range position for the valve say 70% and say that this should match your valve cv.

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