A: Area
C: Discharge coefficient (non-dimensional)
d: density ( water density = 1000kg/m³)
D: Diameter
g: Gravity 9.8 m/s²
K: Flow coefficient (dimensional) (Kv)(Cv)
Q: Flow rate
SG: Specific gravity (1 for water)
v: Velocity
Δh: Head Drop (high of fluid)
ΔP: Pressure Drop

K		=	Q	/ sqrt(	ΔP	/	SG	)
cfs cfh cfm cm³/s gpm (US) in³/s l/h l/min l/s m³/h m³/min m³/s yd³/h yd³/min yd³/s	atm bar inH2O inHg kp/cm² kPa in/ft2 lbf/ft2 MPa mbar mH2O mmH2O mmHg mmWC mWC Pa PSI torr		cfs cfh cfm cm³/s gpm (US) in³/s l/h l/min l/s m³/h m³/min m³/s yd³/h yd³/min yd³/s		atm bar inH2O inHg kp/cm² kPa in/ft2 lbf/ft2 MPa mbar mH2O mmH2O mmHg mmWC mWC Pa PSI torr

K = Cv, when K is referenced in [gpm] [psi] units.
K = Kv, when K is referenced in [m³/h] [bar] units.

K		=	C	· sqrt( 2 /	d	) · (	D	)	² · π/4
cfs cfh cfm cm³/s gpm (US) in³/s l/h l/min l/s m³/h m³/min m³/s yd³/h yd³/min yd³/s	atm bar inH2O inHg kp/cm² kPa in/ft2 lbf/ft2 MPa mbar mH2O mmH2O mmHg mmWC mWC Pa PSI torr				g/cm³ g/mm³ kg/m³ lb/ft³		cm ft in m mi mm nmi yd

K = Cv, when K is referenced in [gpm] [psi] units.
K = Kv, when K is referenced in [m³/h] [bar] units.

K		=	C	· sqrt(2/(1000·	SG	)) · (	D	)	² · π/4
cfs cfh cfm cm³/s gpm (US) in³/s l/h l/min l/s m³/h m³/min m³/s yd³/h yd³/min yd³/s	atm bar inH2O inHg kp/cm² kPa in/ft2 lbf/ft2 MPa mbar mH2O mmH2O mmHg mmWC mWC Pa PSI torr						cm ft in m mi mm nmi yd

K = Cv, when K is referenced in [gpm] [psi] units.
K = Kv, when K is referenced in [m³/h] [bar] units.

K1		<=======>	K2
cfs cfh cfm cm³/s gpm (US) in³/s l/h l/min l/s m³/h m³/min m³/s yd³/h yd³/min yd³/s	atm bar inH2O inHg kp/cm² kPa in/ft2 lbf/ft2 MPa mbar mH2O mmH2O mmHg mmWC mWC Pa PSI torr		cfs cfh cfm cm³/s gpm (US) in³/s l/h l/min l/s m³/h m³/min m³/s yd³/h yd³/min yd³/s	atm bar inH2O inHg kp/cm² kPa in/ft2 lbf/ft2 MPa mbar mH2O mmH2O mmHg mmWC mWC Pa PSI torr

K = Cv, when K is referenced in [gpm] [psi] units.
K = Kv, when K is referenced in [m³/h] [bar] units.

Kv		<=======>	Cv
[m³/h] [bar]			[gpm] [psi]

Cv		<=======>	Kv
[gpm] [psi]			[m³/h] [bar]