Figure 55  General  Gas 01 – Compressed Air Distribution

Compressed air is normally distributed around a ring main loop to maximize efficiency when some demands are not in use. When all in-flows and all out-flows have been defined by flow demands then the total flow in and total flow out must be equal (or the system cannot be solved since the system would not represent a valid condition). However by incorporating an air receiver into the model, the excess flow can be accommodated to allow the model to be solved.

To calculate pressure loss the General Fundamental Isothermal Flow Equation has been used. The pressure loss and flow velocities in this system are relatively small & the hence the use of an isothermal flow equation should provide good results.

View the Results Sheet to see tabulated results or use the mouse to hover over a pipe, a node, or a component, to display the calculated results in a pop-up pane. The exit velocity of the gas in each pipe can be seen on the pop-up pane when hovering over a pipe in Results Mode. In addition, the pipe color matches the magnitude of exit velocity accordingly to the color key for exit velocity (ft/sec). The exit velocity is also shown on the Result Sheet of tabulated data. The British Compressed Air Society suggests using velocities of less than 20 ft/sec, to prevent carriage of moisture and debris along the pipe lines, however in a short drop section an air velocity up to 50 ft/sec may be acceptable.