The performance of flowmeters can be affected by a dimensionless unit called the Reynolds Number. It is defined as the ratio of the liquid's inertial forces to its drag forces.

Laminar and turbulent flow are most common in flow regimes or in liquid flow measurement operations but there is also transitional flow.

If we want to calculate the Reynolds number , we can use the following equation

R = 3160 x Q x Gt D x µ

where:
R = Reynolds number
Q = liquid's flow rate, gpm
Gt = liquid's specific gravity
D = inside pipe diameter, in.
µ = liquid's viscosity, cp