The accuracy to which a pipeline system is balanced can be changed. The balance options for a pipe system are configured on the Calculations tab of the Configuration Options dialog.


Most systems can be solved without any changes to the Calculation options, however these options are included for experimental use when a balanced solution cannot be found. Widening of these parameters may give results where the flow into the system and out of the system do not balance and/or the pressure results throughout the system will not agree with the sum of the pressure drops through the individual pipes.


A balanced solution may not always be found if the system contains components which ‘fight’ each other. If a pump is placed in a pipeline, the change in flow rate will be related to the head added by the pump and the extra pipeline friction losses. In some circumstances, when balancing a system that includes a number of pumps, the adjustment of the flow rate in one pipe/pump combination may generate a disproportionate change of flow rate in another pipe/pump combination, which itself may produce a counter acting effect to the previous flow rate adjustment. Thus the program would oscillate between two possible solutions, neither of which will give the normal expected degree of accuracy.


It is normally better to change the system design to overcome these sorts of problem rather than proceed with a design where it is difficult to predict an accurate result (since this likely indicates that there is a true design problem).


Note: We recommend that you do not change these values, unless it becomes necessary to solve a finally balanced system. 


A screenshot of a calculator??Description automatically generated

Figure 46  Calculation settings


The following adjustments can be made:


Feature

Description

Method of Solution

Non-Compressible or Compressible flow calculation engine

Method of Calculation

Equation used to calculate friction loss. 

Final Node Balance 

Balance pressure at all nodes to this accuracy

Calculation Parameters

A set of values that are used during convergence to determine a solution. The actual parameters vary depending on the Method of Solution selected and the Method of Calculation equation that is selected.

Reset All entries to the Default Values

Restore the standard settings for the calculation parameters.



For liquid systems the Method of Solution selected should always be ‘Non-Compressible Flow’ and the Method of Calculation equation should be ‘Darcy-Weisbach’. These give the most accurate results possible for liquid systems.


For gas systems the Method of Solution selected should normally be ‘Compressible Gas Flow’. The Method of Calculation equation should then be selected to meet any specific needs of the system. In most cases the General Fundamental Flow Equation should be selected since this is the most generally applicable, however the user can choose from additional equations, such as the AGA equation, the Weymouth equation, the Panhandle A equation, and others, in order to produce calculation results that are based on the equation that is normally used for their ‘type’ of gas system.