When you add or edit a Series Pipe Merging operation, the Series Pipe Merging Operation Editor dialog box opens. Operations have two sets of parameters, Settings and Conditions.

1. Click the Settings tab to edit settings.
   • Maximum Number of Removal Levels—Select the number of levels of pipes that get removed per iteration of the Series Pipe Merging operation. The maximum number of removal levels is 50. This is because in the absence of any other limiting factors (conditions, protected elements, non-removable nodes, etc.) one series pipe removal iteration will effectively halve the number of pipes. A second iteration will again halve the number of pipes, and so on. Therefore, 50 is the practical limit for removal levels.
   • Dominant Pipe Criteria—Select the criteria by which Skelebrator determines the dominant pipe. The dominant pipe is the pipe whose properties are retained as appropriate. For example, when merging a 6-in. pipe and an 8-in. pipe, if diameter is selected as the dominant pipe criteria then the larger diameter pipe (e.g., 8-in.) will provide the properties for the new pipe. That is, the 8-in. pipe's diameter, roughness, bulk reaction rate, etc. will be used for the new pipe.
   • Use Equivalent Pipes—Select Use Equivalent Pipe if you want Skelebrator to adjust the merged pipe properties as such to attain equivalent hydraulics as the two merged pipes.
   • Equivalent Pipe Method—Select whether you wish to modify the dominant pipe roughness or the dominant pipe diameter for the equivalent pipe calculations.
     • Modify Diameter - If modify diameter is selected, the new pipe's roughness is kept constant and the diameter adjusted such that the head loss through the pipe remains constant.
     • Modify Roughness - If modify roughness is selected the new pipe's diameter is kept constant and the roughness adjusted such that the head loss through the pipe remains constant.
       Note: When using Darcy-Weisbach for the friction method, Modify Diameter is the only available selection since calculated equivalent roughness can be invalid (negative) in some circumstances.
   • Load Distribution Strategy—Select how you want the load distributed from junctions that are removed.
     • Equally Distributed puts 50% of the load on the starting and ending junctions of the post-skeletonized pipe.
     • Proportional to Dominant Criteria assigns loads proportional to the attribute used to select the dominant pipe. For example, if diameter is the dominant attribute and one pipe is 6-in., while the other is 8-in. (14-in. total length), 8/14 of the load will go to the upstream node, while 6/14 will go to the downstream node.
       Note: For the length attribute, load assignment is inversely proportional, such that the closest junction gets the majority of the demand.
     • Proportional to Existing Load maintains the pre-skeletonization load proportions.
     • User-Defined Ratio allows you to specify the percentage of the load applied to the upstream node in the post-skeletonized pipe.
       Note: If either of the uncommon nodes of the two pipes being merged are not junction nodes, then the selected load distribution strategy is ignored and all load is moved to the junction node. If both uncommon nodes are not junctions, then skeletonization is only carried out if the common junction node has zero demand.
   • Upstream Node Demand Proportion—Set a user-defined load distribution percentage. Set the percentage of the node demand that you want applied to the upstream node adjacent to the removed sections. This parameter is only available if you select User Defined in the Load Distribution Strategy drop-down list. Upstream in this context relates to the physical topology of the pipe and its nodes and may not correspond to the direction of flow in either the pre-skeletonized or post-skeletonized pipe.
     Note: The resulting pipe from a Series Pipe Merging operation is routed in the same direction as the dominant pipe. Therefore, upstream and downstream nodes relate to the topological direction of the dominant pipe. If check valves are present, then the resulting pipe is routed in the direction of the pipe that contains the check valve. If check valves are present in both pipes and those pipes oppose each other then skeletonization is not performed.
   • Apply Minor Losses—Select Apply Minor Losses if you wish for Skelebrator to preserve any minor losses attached to the pipes in your network. For Series Pipe Merging the minor losses for the original pipes are summed and added to the resulting pipe. If this option is not selected then the minor loss of the resulting pipe will be set to zero.
     Note: To combine only pipes with the same hydraulic characteristics (i.e., diameter and roughness), create a Series Pipe Removal Operation and click the Conditions tab. Then, add a pipe tolerance condition of 0.0 and a roughness tolerance condition of 0.0. Also, make sure to deselect the Use Equivalent Pipes check box.
   • Allow Removal of TCVs—Activate this option by checking the box to allow Skelebrator to remove TCVs during the Series Pipe Merging operation.
2. Click Conditions to edit or create conditions.
   1. Click Add to add conditions. You can add pipe and/or junction conditions. You can add more than one condition.
   2. Or, select an existing condition and click Edit to modify a selected condition. You can add and edit Junction and Pipe Conditions.
      Note: In the case where not all nodes connected to the two pipes are junctions, tolerances are only evaluated based upon the junction type nodes. For example, if a tolerance of 5gpm was defined this would not invalidate the merging of two pipes that had one uncommon node that was a pump, for example. The tolerance condition would be evaluated based only upon the two junction type nodes.

The Pipe Condition Editor allows you to set select parameters that determine which pipes are included in the skeletonizing process. Tolerances can also be specified for both pipe and junction conditions.

In the context of series pipe merging, pipe tolerances are calculated between the specified attribute of the two pipes to be merged. For example, a tolerance on diameter of 2-in. means that only pipes within a range of 2-in. diameter of each other will be merged (i.e., a 6-in. and an 8-in. pipe would be merged, an 8-in. and a 12-in. pipe would not).

In the context of series pipe merging, junction tolerances are calculated on all present junctions. If all three nodes are junctions, then all three junctions will be used to evaluate the tolerance. For example, a tolerance of 10 ft. on elevation would mean that the two pipes would not be merged unless all of the three junctions had an elevation within 10 ft. of each other.