ASME MFC 8M : 2001 : R2011

Foreword
Standards Committee Roster
Introduction
1. Scope
2. Field of Application
3. References
4. Pressure Taps
4.1 Location of Pressure Taps in Horizontal Pipes
4.2 Location of Pressure Taps in Vertical Pipes
4.3 Pressure Taps and Connections
4.4 Practical Requirements
5. Block Valves
5.1 General
5.2 Valve Passages
6. Condensation Chambers
7. Gas Collecting Chambers and Settling Chambers
7.1 Gas Collecting Chambers
7.2 Settling Chambers
8. Special Techniques Used as Protection Against Very
     Cold Ambient Conditions
9. Seal Pots and Purge Systems
9.1 Seal Pots
9.2 Purge Systems
9.3 Rodding Units
10. Lead Lines
11. Installation
11.1 Arrangement of Valves
11.2 Arrangement of Lead Lines
Figures
1. Typical Arrangements for Pressure Taps
2. Condensation Chamber Characteristics, Types A,B and
     C
3. Range of Application of Condensation Chambers
4. Arrangement of Wall Mounted Gas Collecting Chambers
     and Valves
5. Settling Chamber
6. Seal Pots - Metered Fluid Heavier Than Sealing
     Fluid
7. Seal Pots - Metered Fluid Lighter Than Sealing
     Fluid
8. Example of Purge System Installation
9. Example of Purge System Installation in the Case of
     Long Lead Lines
10. Horizontal Installation for Clean Liquids -
     Secondary Device Below Pipe Line
11. Horizontal Installation for Cold Clean Liquids -
     Secondary Device Above Pipe Line
12. Vertical Installation for Hot Clean Liquids
13. Horizontal Installation for Clean Noncondensable
     Gases - Secondary Device Above Pipe Line
14. Horizontal Installation for Clean Noncondensable
     Gases - Secondary Device Below Pipe Line
15. Vertical Installation for Clean Noncondensable
     Gases - Secondary Device Above Pressure Taps
16. Vertical Installation for Clean Noncondensable
     Gases - Secondary Device Below Pressure Taps
17. Horizontal Installation for Vapor (Steam),
     Condensable Gases, or Dirty Gases - Secondary
     Device Below Pipe Line
18. Alternative (Closed-Coupled) Horizontal
     Installation for Vapor (Steam) - Secondary Device
     Below Pipe Line
19. Horizontal Installation for Vapor (Steam),
     Condensable Gases, or Dirty Gases - Secondary
     Device Above Pipe Line
20. Vertical Installation for Vapor (Steam),
     Condensable Gases, or Dirty Gases - Secondary
     Device Below Pressure Taps
21. Horizontal Installation for Clean Wet Gases -
     Secondary Device Below Pipe Line
22. Alternative Horizontal Installation for Clean Wet
     Gases - Secondary Device Below Pipe Line
23. Horizontal Installation for Clean Wet Gases -
     Secondary Device Above Pipe Line
24. Vertical Installation for Clean Wet Gases -
     Secondary Device Below Pressure Taps
25. Vertical Installation for Clean Wet Gases -
     Secondary Device Above Pressure Taps
26. High-Pressure/Temperature Steam Installation for
     Vertical Pipe
27. High-Pressure/Temperature Steam Installation for
     Horizontal Pipe
Tables
1. Condensation Chambers
2. Properties of Sealing Liquids
3. Internal Diameter of Lead Lines
4. Applications
Appendices
A. Formulas for Differential Pressure Calculation
     When Seal Pots Are Used
B. Description of Typical Rodding Units
Figures
A1. Differential Secondary Device With a U-Tube Used
     With Seal Pots
A2. Differential Secondary Device With an Equalizing
     Vessel on One Branch, Used With Seal Pots
B1. Rodding Unit
B2. Arrangement of Rodding Unit and Settling Chamber

Explains the practices and means which allow the pressure at a head type primary device to be conveyed to the secondary device in a flow measurement system without introducing unnecessary measurement uncertainties. Concerned only with the transmission of the pressure difference developed by a head type primary flow element.