Written by Jerry Ratzlaff on . Posted in Flow Instrument

## Orifice center of head formula

 $$\large{ h = \frac{ \left ( \frac{ Q }{ C_d \; A_o } \right) ^2 }{ 2 \; G } }$$

### Where:

 Units English Metric $$\large{ h }$$ = orifice center of head $$\large{ in }$$ $$\large{ mm }$$ $$\large{ A_o }$$ = orifice area $$\large{ in^2 }$$ $$\large{ mm^2 }$$ $$\large{ C_d }$$ = orifice discharge coefficient $$\large{ dimensionless }$$ $$\large{ Q }$$ = orifice flow rate $$\large{\frac{ft^3}{sec}}$$ $$\large{\frac{m^3}{s}}$$ $$\large{ G }$$ = orifice gravitational constant $$\large{\frac{lbf-ft^2}{lbm^2}}$$ $$\large{\frac{N - m^2}{kg^2}}$$