Selecting elements based on demand pattern can be accomplished in the Demand Control Center:

1. Open the Demand Control Center from the Components menu
2. Filter the pattern column to the desired pattern. 
3. Choose the "Create Selection Set" option to create a selection set of the elements using that demand pattern.  There might be several different types of node elements which contain the pattern (junctions/hydrants/etc). They each have different tabs in the Demand Center so you will have to filter each tab separately and add them to the selection set you created on the first node element type.
4. Click each tab, repeat the filter on pattern, then click “add to selection set”.  Choose to add this one to the one that was created for junctions, and repeat for any other tabs.
5. Close the Demand Control Center and double click the selection set from the selection set manager.