Example: 3” line with K17 upright
Whatever the hydraulics prove?
NFPA standards does no specify, but FM Global 2-0 data sheet implies pipes up to 4" OD in storage applications are allowed. You could check with the sprinkler manufacturers to see if they have a recommendation.
Thanks Emmanuel. I downloaded a copy of FM Global 2-0.
My reason for asking is: When does the branchline of a directly installed sprinkler become an obstruction to that sprinkler? An example might be 1 or more K5.6 standard spray upright sprinkler directly attached to an 8" pipe running through a tunnel. Hydraulically, it is sound, but is the pipe obstructing the sprinkler spray pattern.
Follow the obstruction rules
FM Global and NFPA have different rules for installation.
CMSA sprinklers have a maximum branch line pipe size of 4" and after that a 12" riser nipple must be used. In some instances the obstruction rules are more stringent for CMSA sprinklers over SSP/SSU, in other instances the rules for SSP/SSU are more stringent.
Answers like: "Read the code" aren't very helpful.
Depending on what you are designing to, is what obstruction rules to follow along with what the sprinkler manufacture also says
The answer is anything less than 3"
NFPA 13 - 2016 - 22.214.171.124.1.8 - The requirements of 126.96.36.199.1.3 shall not apply to sprinkler system piping less than 3 in. in diameter.
188.8.131.52.1.3 - Minimum Distance from Obstuctions (see section)
Thanks! That's exactly what I was looking for. That is a perfect example of the CMSA vs. SSP/SSU.
CMSA obstruction rules say:
184.108.40.206.2 Branch Lines. Upright sprinklers shall be positioned with respect to branch lines in accordance with one of the following:
Upright sprinklers shall be permitted to be attached directly to branch lines less than or equal to 4 in. (100 mm) nominal in diameter.
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