Lamina Flow Elemene의 차압측정을 통해 Volume을 측정하고, 내장된 온도 센서, 절대압 센서를 이용해 Mass를 구하는 방식이다.

Equation 1
Q = (P1 – P2)πr4/8ηL

Where
Q = Volumetric Flow Rate
P₁ = Static Pressure at Inlet
P₂ = Static Pressure at Outlet
r² = Hydraulic Radius of Restriction
η = (eta) Absolute Viscosity of Fluid
L = Length of Restriction

Equation 2
Q = K(∆P/η)

Where
K = constant dependent upon
the geometry of the LFE.



Equation 3
M = Q(Ts/ Ta )( Pa/ Ps)(Zs / Za)

Where
M = Mass Flow
Q = Volumetric Flow (From Equation 2)
Ts = Absolute Temperature @ Standard Condition in Kelvin
Ta = Absolute Temperature @ Flow Condition in Kelvin
Pa = Flow Absolute Pressure
Ps = Absolute Pressure @ Standard Condition
Za = Compressibility at Measured Conditions
Zs = Compressibility at Standard Conditions