I have a question as the followings, and seek for your advice. Thanks!
There is a fan with discharge pressure about 700 mmH2O(G).
I am trying to design an orifice meter plate with 0~100 mmH2O range
corresponding to 0~1500 NM3/H air. It is in 8" sch 10 pipe.
(There is about 500 mmH2O(G) back pressure downstream the orifice)
After sizing the orifice, the result is
beta ratio=0.63
permanent pressure loss= 60 mmH2O
max differential pressure is 2100 mmH2O ( in Vena contracta ).
My question is it means at some point downstream the orifice plate,
the pressure will become vacuum, then recover some pressure to 700-60=640 mmH2O(G)
Is there any problem for the flow thru this orifice?
i.e. Is flowing possible through this orifice, as it will create vacuum somewhere?
Thanks!