Example 7-2 Flow through Sharp Edged Vent Orifice

Example 7-2 Flow through Sharp Edged Vent Orifice (adapted after Ref. [29]) 

A small hole has been deliberately placed in a vessel near the top to provide a controlled vent for a nitrogen purge/blanket. The hole is 0.2-inch diameter with the vessel operating at 150 psig at 100°F. Determine the flow through this vent hole. Assume it acts as a sharp edged orifice. 

At critical conditions, the maximum flow through the nozzle or orifice is [29] 

Discharge coef. C0 = assumed = 1.0 (Note, could calculate Re to verify.) 

0 = discharge coefficient for sharp-edged orifice = 0.61 for Reynolds Number 30,000 and not sonic 

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