Linear Flow Orifice Meter Equations

Total Flow Rate Through Weir

 $$ Q = C_o [h + {2 \over 3} s] $$

The constant of proportionality, Co :

 $$ C_o = C_d W \sqrt{2 g s} = {Q_{max} \over H_{dmax}}$$

Flow Through Rectangular Base of Weir

 $$ q_w = {2 \over 3} W C_d \sqrt{2g} [{{(h + s)}^{3 \over 2}} - {h^{2 \over 3}}] $$

Rectangular Base Width

 $$ W = Q_max \over {C_d {H_dmax^{3 \over 2}} \sqrt{3 g Pi_Sutro}} $$

Rectangular Base Height

 $$ s = {3 \over 2} \Pi_{sutro}H_{dmax} $$ 
 $$ Pi_{sutro} = {Q_min \over Q_max} =  {{2 \over 3}s} \over {H_dmax} $$

Profile of Curved Portion

 $$ y = {W \over 2} [1 - {s \over \Pi} tan^{-1} \sqrt{x \over s} ]$$