1. <?xml version=“1.0” encoding=“UTF-8”?>  
2.   
3. <Package xmlns=“http://soap.sforce.com/2006/04/metadata”>  
4.   
5.     <types>    
6.         <members>Process_Builder_API_Name-3</members>   
7.         <name>Flow</name>    
8.     </types>  
9.   
10.     <version>36.0</version>  
11.   
12. </Package>  

This will retrieve version 3 of the “Process_Builder_API_Name” process.