Constants for virtually every model of Orifice Plate, Nozzle, Venturi,  Multi-Port Averaging Pitot, V-Cone,  Solve for Liquid, Gas, Vapor fluid states, Exclusive engineering features, continual checks for Cavitation, Flashing Flows, Critical Flowrate computations, Choked Flow-Rate Computations, Restrictive Orifice Computations, Energy, Overall Pressure Loss, Unique solutions derived by R.W. Miller for computations outside standard limits.
R.W. Miller & Associates







The Flow Consultant Software


The only software endorsed by Richard W. Miller covering all differential producers

and exact equations of state presented in

 The Flow Measurement Engineering Handbook

The Flow Consultant includes Restrictive Orifice, Turbine meters, Vortex meters, Fluidic meters, Swirl meters, All frequency/digital output meters, Fixed Geometry and V-Cone Flowmeters.  Constants for the following Flowmeters: Annubar, Elbow, Foxboro Integral Flow Orifice (IFO), Preso, Multiport Averaging (MPA), Taylor Wedge, Veris Verabar and the ability to enter the flow coefficient.  Users interested in other devices may contact us for consideration.

Order Version 9 

Version 9 is now available for purchase or upgrade.

Tap into a Wealth of Knowledge

The FLOW CONSULTANT ™continuously monitors input throughout the computational process.  Warnings are issued and default data displayed for entries outside the manufacturer's recommendations or published standards. 

Constants are built in for virtually every model of Orifice Plate, Nozzle or Venturi are included.  Solve for Liquid, Gas and Vapor fluid states.

Exclusive engineering features include continual checks for Cavitation or Flashing Flows, Critical (Choked) Flow-Rate Computations,
Restrictive Orifice Computations, Energy and Overall Pressure Loss.
Unique solutions derived by R.W. Miller for computations outside standard limits.

Meters Covered By The FLOW CONSULTANT ™

Orifice Plates
Concentric Orifice Segmental Eccentric

Conic Orifice
Flange Taps
Corner Taps
D and D/2 (Radius/Vena Contracta Taps)
Honed Orifice Run, Flange Taps
Honed Orifice Run, Corner Taps
IFOA with Square Edge (Foxboro)
IFOA with Quadrant Edge (Foxboro)

Flange Taps at Top (180 deg)
Vena Contracta Taps at Top (180 deg)

Flange Taps at Top (180 deg)
Flange Taps at Side (90 deg)
Vena Contracta Taps at Top (180 deg)
Vena Contracta Taps at Side (90 deg)

Pipe Taps (Restrictive Orifice)
Quadrant Orifice
Choked Flow Orifice, D & d taps

Compact Orifice 405P (Rosemount)
          Beta=0.4 or   Beta=0.65

Enter Discharge Coefficient

Machined In (machined)
7 deg Exit Cone
Machined In (machined)
15 deg Exit Cone

Rough Cast In (cast)
7 deg Exit Cone
Rough Welded Sheet Iron In (fabricated)
7 deg Exit Cone

Rough Cast In (cast)
15 deg Exit Cone
Rough Welded Sheet Iron In (fabricated)
15 deg Exit Cone

Enter Discharge Coefficient
Flow Nozzles

ASME long radius
ASME long radius w/diffuser

ASME throat tap
ASME throat tap w/diffuser
ISO (ISA 1934 Nozzle)
Venturi Nozzle (ISA in-diffuser exit)
Enter Discharge Coefficient




Fixed Geometry
Elbow Meters Foxboro Integral Flow Orifice (IFO) Wedge Meters Compact Orifice 405P (Rosemount)

Elbow Short 45deg
Elbow Long 45deg

Elbow Short 22.5deg
Elbow Short 22.5deg
Enter Flow Coefficient for Elbow Meter

IFO .02
IFO .034
IFO .0595
IFO .0995
IFO .159
IFO .25
Enter Flow Coefficient for IFO

Taylor Wedge Meter h/D=0.2
Taylor Wedge Meter h/D=0.3
Taylor Wedge Meter h/D=0.4
Taylor Wedge Meter h/D=0.5
Enter Flow Coefficient for Wedge Meter


Multiport Averaging

Annubar 10
Annubar 15/16
Annubar 25/26
Annubar 35/36
Annubar 45/46

Preso 22
Preso 31.73
Preso 57.15

Veris Verabar 05
Veris Verabar 10
Veris Verabar 15
Veris Accelabar 05
Veris Accelabar 10

Enter Flow Coefficient for MPA
Linear Meters


Turbine Swirl Fluidic

All named meters are registered trade marks TM of their manufacturer.


The Flow Consultant is a modular design.  Each segment of our program is compartmentalized for total design flexibility.  Users can change any design element  without any down time to re-compute. 

For example, modify the Beta Ratio or Pipe Size to immediately update the Flow-Rate or vary the Flow-Rate for immediate change to the Beta Ratio.

Print Screens Shots directly to your printer from The FLOW CONSULTANT ™  without going into a separate application.

Standards and Reference Texts

Detail Method, Gravity Method and Heating Value

Accepted US standard for the use of orifice meters used to meter natural gas and other fluids.

Accepted standard used by many industries for the metering of many fluid and in particular steam and water flow measurement.

For Throat Tap nozzles

ANSI 2530
The American National Standards Institute's (ANSI) standard that duplicates AGA 3

ANSI 2530/AGA3/ Buckingham/Spink
The original AGA/ANSI/ASME standard for the metering of fluid with the flange tap orifice Flowmeter. Once widely used by all US industries in designing flow measurement equipment, this standard has been superseded by the above reference documents. 

API Chapter 14
The ANSI standards for the metering of Natural gas.

ISO-5167 *  The International Standards Organization's (ISO) Standard, now in three parts, for the metering of all fluid using Orifices (all tapings), Nozzles, and Venturi Meters.

Miller (1983 to date)


S-GERG Equation of State for Natural Gas is widely used in Europe for custody transfer measurements.  S-GERG requires input of the heat content BTU (Joules), the relative density (Specific Gravity) and the mole fraction of carbon dioxide.

Spink (1935 to date)

Important Notice

Regarding  ISO 5167, ASME -3M, and AGA/API/ANSI 2530

From R.W. Miller

In April 2004 ASME approved separate standards for Orifice, Nozzle, and Venturi Flowmeters. There is a major change to the

  • Orifice Discharge coefficient computational equation for all tappings
  • The Gas Expansion factor equation for all tappings

ASME-3M and International standard ISO 5167 now use identical equations.

Other US standards (API/AGA/ANSI) no longer agree with International practice for either calculation.

Only The FLOW CONSULTANT software contains the new equation.

Fluid Properties

Only The FLOW CONSULTANT  software solves for fluid properties modules using the exact solution and not the generalized state equation used in most software. These solutions can be in error by several percent or more.

The Fluid Properties modules contain equation constants for computing the properties for hundreds of  fluids.  Fluid Properties constants The FLOW CONSULTANT ™  are maintained in accordance with all the current reference texts and standards.  

Enter only Pressure and Temperature to compute Base Compressibility, Base Specific Gravity, Base Density, Flowing Compressibility, Flowing Density, Flowing Specific Gravity, Liquid Compressibility, Viscosity or the Isentropic Exponent.   

Enter your own fluid properties through our custom fluid screen.

AGA-8 for Natural Gas Heating Value, Gravity Method and the Detail Method

AIChE Constants for over 250 fluids. Exact solution correcting for Liquid Compressibility, Temperature and Pressure. 

ASME - equations for Water, Saturated Steam and Superheated Steam

Modified Benedict Webb Rubin exact equations for Air, Ammonia, Argon, Butane, CO2 , Ethane, Heptane, Hexane, I-Butane, I-Pentane, Methane, Nitrogen, Octane, Oxygen, Pentane, Propane and Propylene. 

NX-19and S-GERG for Natural Gas

Fluid Property Reference  


US and SI units can be interchanged and modified at any time without the time consuming task of  recalculating. 
The Flow Consultant operates on SI units.  Converting existing data is automatic when units change.

Storage of user defined templates allows for infinite unit combinations with just one click of the mouse.

All units are verified to industry standards for the current design conditions. 

If you don't find your units in our software, contact us and we will add it.

Special Factor Corrections

Mercury Meters

Two-Phase Flow/Multi-Component Flow using either the James or Murdock flow rate computational solution

Drain and Vent Hole

Saturated Liquids

Accuracy / Uncertainty Calculations

The estimated uncertainty based on the measured and unmeasured variables used in the flow rate computation are combined in accordance with the selected standards procedures to give the overall uncertainty (Accuracy).

The estimated uncertainty of the discharge coefficient and gas expansion factor is computed using the appropriate standards. The user inputs the uncertainties of the other measured or unmeasured variables.

Flow Versus Differential Pressure

Unique to The FLOW CONSULTANT ™ is the exportable (and printable) tabulation shown below. The Standard graph is exported to Microsoft Excel via the Export Excel Function.

First you select the number of points to compute then the screen displays:

1.  Scaled flow rate as a function of the differential
2.  The exact flow rate corrected for the discharge coefficient and gas expansion factor for flow rate
3.  The directional Bias error between actual and scaled flow rate at the measured differential.

Engineering Results

Review the Stress data, deflecting and estimated bias error when printing your datasheets.

Data Storage

The Flow Consultant is backed by proprietary Microsoft Access TM.  Our software provides a utility to create and maintain multiple databases for easy to use, directory based storage.  Create a new data warehouse by simply picking a name and destination.

Create custom external data objects with The Data Exporter.  The Data Exporter creates user defined Microsoft Access TM tables export to spreadsheets, corporate databases or any other means of analysis.

Using the Data Exporter, share data with Microsoft Excel TM  spreadsheets.

ISA DataSheet for Microsoft Excel TM

Data is exported to an Excel worksheet in the ISA format.

This puts the full capabilities of Excel graphical and mathematical capabilities at your fingertips. Included on the standard printout is a data and graphical showing dp vs flow-rate.

Or Modify the ISA format data sheet to create a custom company specific worksheet.

Standardized ISA Datasheet ships with the application.
Requires MS ExcelTM licensing (not included).


Our simplified interface for entering mole fraction percentages solves the often cumbersome detail method solution.  

Use the Detail dropdown list box to select from previous calculations or the examples to quickly populate the percentages. 
The FLOW CONSULTANT ™ is preconfigured with examples from the AGA-8 Standard.

Select the fluid components you want, fix on certain values and normalized the unselected components.


AGA8 Fluid Inputs (Mole Fractions)

  Argon, CO, CO2, Ethane, H2, H2S, i-Butane, i-Pentane,  Methane, N2, n-Butane, n-Decane, Helium, n-Heptane, n-Hexane, n-Nonane, n-Octane,  n-Pentane, O2, Propane, Water.

Gas Mixtures

Developed by R.W. Miller, the Gas Mixtures interface expands the AGA-8 interface with additional fluids not included in the AGA-8 standard.


In addition to AGA8 Fluid Inputs:

Acetylene, Air, Ammonia, Butylene, Chlorine, cis-2-Butene, Ethene, IsoButene, Propene, trans-2-Butene.

Also includes:

S-GERG    Heating Value, Gravity and CO2
AGA8        Heating Value, Gravity and CO2
AGA8        Gravity, N2 and CO2


Pipe Sizes

Select from all standard pipe sizes or manually enter pipe size.

The thermal expansion factor is calculated by selecting from these pipe materials and primary element materials:

Carbon Steel
Chrome-Moly Steel
Stainless Steel (300, 304, 316, 321, 400)

Super Duplex

Hastelloy B
Hastelloy C
Inconel X, annealed

Inconel, 624
Haynes Stellite

Monel 400

Enter the Thermal Expansion Coefficient for pipe material and primary element material if your materials are not in the pick list.

Existing Flow Consultant users may note some older materials are no longer listed.  These can still be used by Entering the Thermal Expansion Coefficient.  Removed materials were Yellow Brass, Beryllium Copper, Cupronickel and Pyrex Glass.  If you are upgrading data from older versions of the Flow Consultant, these will default to entering the thermal expansion coefficient.

Noise Calculation

The ISA SP1, SP2, etc are ISA standards compatible or identical to the work on noise done by Hans Bauman, Masonelian for control valves. 

This work is considered the basis for the most practical solution for noise on restrictive devices available in the literature.  It is the source document for the solution used for the Flow Consultant noise calculation.

Restrictive Orifice 

An independent review of our competition's software shows the following:

  • Only the FLOW CONSULTANT computes the differential across the plate rather than assume the differential is the overall pressure loss.
  • Only the FLOW CONSULTANT uses the exact Roark equations for calculating stress and deflection.
  • Only the FLOW CONSULTANT uses the yield stress based on the flowing temperature.
  • Only the FLOW CONSULTANT checks for plate flatness to the standards specifications


Users can suppress or print any warnings or error messages generated during the computational process. 

Our detailed specification sheet can be completely customized by using the Data Exporter.

Includes a customizable ISA style datasheet.

Print Screens Shots directly from The FLOW CONSULTANT ™  without going into a separate application.

Print Preview window is now available.

Wide Range Metering

Wide Range Metering Accuracy can now easily be determined by

Step 1 select Flow Vs Dp to determine the +/- Bias, errors that occur by not including changes in discharge coefficient and gas expansion factor with Flow-Rate

Step 2 select Accuracy to determine the+/- error at the lowest acceptable flow rate.

 Combine the bias and precision error by summation and repeat for additional transmitters.

Technical Upgrades within Version 9 are free for the purchased term.

Version 9 licenses are subscription based

System Requirements

Windows 7/Windows 8/Windows 10
The Flow Consultant is always tested to the first release of a new MicrosoftTM operating system.

License Agreement

How to Order



Constants for virtually every model of Orifice Plate, Nozzle, Venturi,  Multi-Port Averaging Pitot, V-Cone,  Solve for Liquid, Gas, Vapor fluid states, Exclusive engineering features, continual checks for Cavitation, Flashing Flows, Critical Flowrate computations, Choked Flow-Rate Computations, Restrictive Orifice Computations, Energy, Overall Pressure Loss, Unique solutions derived by R.W. Miller for computations outside standard limits.

R.W. Miller & Associates   

Users Manual

53 Broad Street 5878
Providence, RI 02903       
United States

Support hours:
Monday to Thursday 9am to 9pm  
Friday 9am to 5pm. 

Limited support hours
Saturday, Sunday and US Holidays

Kindly account for international time differences.  Our Business Hours are Eastern Standard Time (UTC - 5)