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 TNflow - Flow  Measurement  Software
based on ISO 5167:2003

( Version 2.02, May,2006)

TNflow is a stand-alone software.
TNflow is addressing the needs of engineers dealing with fluid flow measurement by means of pressure differential devices. TNflow may be used to calculate:

1. primary device diameter (bore diameter) for declared full scale flowrate and related value of differential pressure, 
2. differential pressure for declared bore diameter and flowrate,
3. flowrate for declared bore diameter and differential pressure. 

 Any of the above calculations is supplemanted by: 

• diameters corrections for thermal expansion, 
• bounds of measurement range calculations, 
• upper limit of upstream pipe roughness calculations, 
• upper limit of sharp edge radius calculations, 
• required upstream and downstream straight lengths calculations, 
• uncertainty analysis of flowrate measurement at a single point and in the entire measurement range,
• bias "linear scale" error analysis. 

 The calculations may be performed for all orifice plates, nozzles, Venturi nozzles and Venturi tubes covered by ISO 5167: 

• orifice plate with corner tappings, 
• orifice plate with D and D/2 tappings, 
• orifice plate with flange tappings, 
• ISA 1932 nozzle, 
• long radius nozzle,
• Venturi nozzle,
• classical Venturi tube with an "as cast" convergent section,
• classical Venturi tube with a machined convergent section,
• classical Venturi tube with a rough-welded sheet-iron convergent section,
• quarter-circle orifice plate (ISO/TR 15377:1998+AC1:1999).

 TNflow calculates fluid properties for the most common fluids:

• water and steam (The 1967 IFC Formulation for Industrial Use, The IAPS Formulation 1985 for Viscosity)
• natural gas (ISO 12213-3, GOST 30319.1-96)
• coke-oven or town gas (Beate-Bridgeman state equation), 
• air (Redlich-Kwong state equation), 
• other gas if its composition is known (Redlich-Kwong state equation), 
• liquid ammonia (Raznievic). 

For other fluids the properties may be declared by user.

Standards used

For pipe diameter D > (or =) 50 mm:
ISO 5167:2003 Measurement of fluid flow by means of pressure differential devices inserted in circular cross-section conduits running full - 
Part 1: General principles and and requirements,
Part 2: Orifice plates,
Part 3: Nozzles and Venturi nozzles,
Part 4: Venturi tubes.

For pipe diameter D < 50 mm:
ASME MFC-14M-2003 Measurement of fluid flow using small bore precision orifice meters
ISO/TR 15377:1998+AC1:1999 Measurement of fluid flow by means of pressure differential devices - Guidelines for specification of nozzles and orifice plates beyond the scope of ISO 5167-1.

Graphs of uncertainty and bias "linear scale" error

TNflow displays the graphs of the uncertainty and of the "linear scale" error over the entire measurement range.
The bias "linear scale" error is a difference between values of flowrate calculated using accurate method:
(where C and E are functions of q),
and values of flowrate calculated using simplified method:
(where B is constant over the measurement range).

Click on an image to see the full size picture:

How to buy TNflow

Click Order TNflow and fill out our online purchase form. Immediately after placing your order, you will receive a pro forma invoice that you can print with your web browser. As soon as we receive your payment via bank transfer we will send TNflow.zip to you as email attachment.

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