New Calculated Sprinkler Hanger Spacing Tool

11/27/2019

Occasionally I come across projects where the contractor (my client) is looking to use listed anchors or attachments that are listed, but have various strengths associated with them.

NFPA 13 lists the maximum spacing for hangers, but this maximum spacing doesn't always address these alternative hanging methods. NFPA 13 addresses these by requiring that any hanger assembly be able to support five times the weight of water filled pipe, plus 250 pounds.

Based on this, I've created a calculator that reverses this process and calculates the maximum spacing for hangers depending upon the pipe size, type, and strength of a hanging element. As this is the first week out I only have I-P units (sorry international friends, I'll continue to work on this), but give it a spin here and let me know what you think in the comments section below.

Don't see the tool below? Click here.

Thanks and for those in the US have a great Thanksgiving week!

2 Comments

Piers Johnson

11/27/2019 11:29:32 am

Shouldn't this table also include a Length of pipe to be supported, otherwise the weight of pipe calculated is only based on 1-ft of pipe. also why is weight of water indicated as kg/m shouldn't his be lbs/ft to be consistent

Joe Meyer

11/27/2019 12:25:40 pm

Piers - Thanks for the catch! The units label was off and is updated.

And yes - the length is incorporated below as the solved variable at the bottom of the calculator.

Most of the time we do the following:
(1) assume a hanger spacing
(2) calculate the weight of the water-filled pipe x pipe length + 250
(3) check that the calculated weight is less than the anchor/fastener capacity
(4) if it's more than the anchor/fastener capacity, then we assume a closer hanger spacing and repeat the process

Instead of iterating, this calculator solves directly for the maximum permissible spacing based on the weakest element in the hanger assembly. Instead of assuming a length (S) in the formula T = 5 x W + 250 where W (lbs) = S (ft) x Wt (lb/ft), we just solve directly for S since we know all the other variables.

New Calculated Sprinkler Hanger Spacing Tool

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