Small-Bore Liquid Orifice Flow Meter Calculator for Excel

This Excel spreadsheet calculates the liquid flowrate from a small-bore orifice meter using the equations defined in ASME MFC-14M-2001. The calculation is iterative, but the spreadsheet is conveniently set up to use Excel's Goal Seek functionality by simply clicking a button.

The equations implemented in the spreadsheet are sourced from ASME MFC-14M-2001 and are given below.

The notation is given below.

• C is the discharge coefficient. D₁ must be supplied in m.  The equation differs for flange taps and corner taps, but a menu in the spreadsheet allows you to pick between the two.
• D₁ and D₂ are the diameter of the pipe and orifice respectively (m)
• A₁ and A₂ are the cross sectional areas of the pipe and orifice (m²)
• ΔP is the pressure drop across the orifice (Pa)
• ρ is the density of the liquid (kg m^-3)
• V₁ is the liquid velocity in the pipe(m s^-1)
• Re₁ is the Reynolds Number in the pipe
• β is the diameter ratio
• μ is the liquid viscosity (Pa s)
• Q is the volumetric flowrate (m³s^-1)

The correlations for the Flange Taps and Corner Taps discharge coefficient are only valid for the following configurations.

The equations are only valid under the following conditions

• Corner Taps: 0.1 < β < 0.8
• Flange Taps: 0.15 < β < 0.7
• 25 mm < D₁ < 50 mm
• 6 mm < D₂ 
• Re > 1000

A β of between 0.3 and 0.7 is practical; below this, the pressure drop is too large for economical operation, and above this, the pressure drop is not large enough for an accurate reading.

The Excel spreadsheet will also calculate the static pressure loss and the head loss from a distance D₁ upstream and 6 D₁ downstream of the orifice.

The spreadsheet is free, and none of the cells are hidden, locked or password protected. Please visit this website regularly for more exclusive, professionally prepared Excel spreadsheets for engineering.

Download Excel Spreadsheet to Calculate Liquid Flow from a Small Bore Orifice Meter