[Sprinklerforum] Re: [External]FM Global obstruction

Thu, 03 Apr 2025 10:39:46 -0700

Kyle,

take a look at FM Data Sheet 8-9, section 2.2.6 (inclusive).  They note a requirement for the deflector to have either a 3'-0" clearance between the top of the storage, or 5'-0" is the sprinkler is an extended coverage model.

Also, there's some pretty good information in data sheet 2-0 regarding obstructions, both in non-storage and storage applications.

sincerely,
Ken Wagoner, SET
Parsley Consulting
3002 Younger Drive
Harrisonville, Missouri 64701-2235
Phone: (760) 745-6181
Visit the website
Please note new street address


On 4/3/2025 10:21 AM, Kyle.Montgomery wrote:

I can’t believe it was FM’s intention to allow, say, a 47” duct to be located directly below the sprinkler and within only a few inches of the deflector. But I am having a hard time finding where something is written to refute that.

 

If it was NFPA 13, I think we’d be saying that it needs to be a minimum of 18” below the deflector before we apply that allowance to allow the pattern to develop.

 

Kyle Montgomery

 

Pre-Construction Manager

Aero Automatic Sprinkler Co.

21605 N. Central Ave.

Phoenix, AZ 85024

Direct: 623.580.7820

Cell: 602.763.4736

[email protected]

 

 

 

From: Ed van Riel <[email protected]>
Sent: Thursday, April 3, 2025 12:07 AM
To: [email protected]
Subject: [External][Sprinklerforum] FM Global obstruction

 

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Here below is a passage from FM 2.0 (2021-10) non-storage.

(2.5.2.5.4.1 Any object up to 4 ft (1.2 m) wide, as measured in the object’s least dimension and in a plane

that is parallel to the floor, does not qualify as an obstruction to the sprinkler’s discharge pattern.)

 

Is anything up to 4ft. wide no obstruction? no matter what the vertical distance from the deflector (or themal element) is?

Or do we have to respect the clearance of 3 ft (0.9 m)?

 


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