Gas pipe sizing - Bouyancy and Residual Pressures

 Product(s):Hevacomp Mechanical Designer
 Area:Netsys Gas


The Netsys Gas Pipe sizing program considers Buoyancy and Residual Pressures during the calculation process.


This document explains how the buoyancy effect is considered in the Residual pressure report in the Netsys Gas program. Consider this small Netsys Gas system:

 This system will produce the following sizing results:

  And the Residual Pressures report for the system:

 The columns in the above report are calculated with the following methods:

Available pressure = Source pressure - Pressure drop in section
Required pressure = Outlet pressure + Section pressure drop - Buoyancy effect
Residual pressure = Available pressure - Required pressure

Where the buoyancy effect is calculated using this formula:

The example system above uses Natural Gas with a buoyancy of 0.68

So for Section 3 in our example Gas layout:

 The residual pressures report shows figures rounded to whole numbers.
This is reflected in the calculation above.


The Netsys Gas program uses the following Gas densities:

Natural Gas0.68 Town Gas0.54 Butane2.48 Propane    1.85
Air1.22 Carbon Dioxide1.72 Methane0.67 Nitrogen1.16
Nitrous Oxide1.84 Oxygen1.33 Exhaust Gasses1.00