Obstructions that prevent sprinkler discharge from reaching the hazard

[Chris RAN]

A college laboratory room (approximately 2,000 sq. ft.) where research is done on lasers. There is no chemical storage. Overhead shelving were installed 21 inches below the ceiling and the installation creates an obstruction to the existing sprinkler heads. The solid shelving units, including the brackets are just over four feet wide. The shelving units are chained to the concrete deck above, but are also attached to the lower ceiling grid but they appear to be adjustable. Light fixtures and heavy duty laser safety curtains add to the difficulty of new sprinkler head locations.
I was looking for opinions on whether you think these units would be considered a “fixed” obstruction.

Thank you in advance.

 

[cdafd]

It looks like they can decrease the shelf width, with no problem and not lose anything.

Or put in open grate shelf

 

[UFT12]

Are these obstructions more than 18" below the deflectors? if so, it seems the large obstruction rule apply. I believe it is impractical to install sprinklers below them so like cdafd said, try to reduce their width.

Also, the heads will have to be placed away from the vertical supports and as symmetrical as possible around them.

 

[TravisMack]

Don't forget that the 2016 edition allows you to be as much as 3" to the side of an object. So, you don't have to be under them like in prior editions.

Travis Mack, SET, CWBSP, RME-G, CFPS
MFP Design, LLC

http://www.mfpdesign.com

 

[chicopee]

Replace the solid shelves with perforated shelves which would be a recommendation during property insurance surveys.