I have seen things like this when the grid is not symmetrical, ie two branch 
lines from one main reducing to a single line attaching to the other main.  
 

 
That is a little extreme though  
 
 
 
 
Todd Williams    

 
Fire Protection Design/Consulting
 
Stonington, CT
 
860-608-4559
 
 
 
 
 

 
 
>  
> On Apr 9, 2026 at 10:11 AM,  <Parsley Consulting 
> (mailto:[email protected])>  wrote:
>  
>  
>   Each time I believe I've  'seen it all' something comes across my desk 
> which rattles my brain in a big way.
>  
>  I'm looking at three calculations for a grid, one of the remote area, the 
> other two are shifted one sprinkler to the East, and one to the West.
>  
>  Top of riser values:
>          
>          RA       1663.44 gpm @ 106.107 psi
>          East    1653.71 gpm @ 106.113 psi
>          West 1609.12 gpm @       97.934 psi
>  
>  I don't believe I've ever seen a peak of a single sprinkler generate a 
> pressure difference of almost 9 psi (RA to West)
>  
>  I've checked all the obvious reasons - modified pipe sizes or lengths, 
> differing flows from sprinklers - and I don't see anything which would cause 
> the peaking results for the West shift
>  
>  I'm open to any suggestions.    Color me baffled.
>  
>  sincerely, 
> Ken Wagoner, SET
>   Parsley Consulting
>  3002 Younger Drive
>  Harrisonville, Missouri 64701-3909
>   Phone: (760) 745-6181
>    Visit the website 
> (https://linkprotect.cudasvc.com/url?a=http%3a%2f%2fwww.parsleyconsulting.com%2f&c=E,1,Y5zKJKPEh1mBEBqSR-VE9cUKl5y-eyP8BpvmE_5j9ZqW2eJbNphYzrCMBZ-2YuX6d-RRkHI4gQ1FV-cvOeCfRC58uZS9NiToZv2mx7909oCqLvCW_n5hDHeK&typo=1)
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