Orifice Meter Calculator

Pipe Inner Diameter

Orifice Diameter

Pressure Tap Type

Differential Pressure

in H₂O

Typical: 10-200 in H₂O for optimal accuracy

Static Pressure

psig

Flowing Temperature

°F

Gas Gravity (Air=1.0)

Natural gas: 0.55-0.70, Methane: 0.554

Molecular Weight

lb/lbmol

MW = SG × 28.97 (calculated from gravity)

Compressibility Factor (Z)

Typical: 0.90-1.00 for natural gas

q_m = (C / √(1-β⁴)) × ε × (π/4) × d² × √(2 × Δp × ρ₁)

C = Discharge coefficient (Reader-Harris/Gallagher)

β = Beta ratio (d/D)

ε = Expansibility factor

Δp = Differential pressure

Flow Measurement