time limitation for dry pipe systems

[crb7]

Hi friends,

Please read this part of NFPA13:2016

A.7.2.3.1 The 60-second limit does not apply to dry systems with capacities of 500 gal (1900 L) or less, nor to dry systems with capacities of 750 gal (2850 L) or less if equipped with a quick-opening device.

This part allow us to omit the time limitation for mentioned systems. for example if I had a project which its pipe volume size is less than 500 gal then the time limitation is not important and if the time of water delivery becomes 120 seconds, there is no problem and its OK.
am I right?

 

[cdafd]

Do you have a quick opening device installed?

 

[cdafd]

I wish this had edit. Qiuck opening not needed for 500 or less


So that is what that button is for, thanks.


CRB7 are you asking a general question or do you have a system that takes two minutes to get to the inspector test??

 

[KoachCSR]

crb7,

I believe you are correct.

Further down in that section of NFPA 13 (2016), 7.2.3.3 states "A system size of not more than 500 gal (1900 L) shall be permitted without a quick-opening device and shall not be required to meet any specific water delivery requirement to the inspection test connection."

Additionally, 7.2.3.1 also states "The system capacity (volume) controlled by a dry pipe valve shall be determined by 7.2.3.2, 7.2.3.3, 7.2.3.4, 7.2.3.5, or 7.2.3.7." (emphasis added by me)

Based on the above, I believe you are correctly interpreting that you don't have a specific delivery requirement to meet. That said, I recommend you confirm with whatever local codes or ordinances may apply, as it is common for local counties or jurisdictions to supplement or substitute their own requirements at times.

cdafd,

There should be an "Edit" option in the bottom right hand corner of your post.

 

[UFT12]

I also agree that you are technically correct. Here it seems we have a paradox. Assuming a rather far fetched example, squeeze all pipes down to as low as, say, 1/4" to have a system way less than 500 gal. Would that take less than 1 min to deliver water through the farthest sprinkler? Most likely not. However the standard is satisfied. But the prudent designer will never size a system like that (given also that there are pipe limitations in the standard) and the committee of 13 rely on that.

 

[TravisMack]

You are correct to an extent. But, there are some over-rides I believe to that. If you have sprinklers in a dwelling unit, you are looking at 15 second delivery time, regardless.

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

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