Use Volume Only to Determine Dry Trip-Time?

12/17/2021

Is it possible to calculate the travel time for water, in a dry system, from the source to the furthest part of the dry system when I only have information concerning the system volume?

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6 Comments

MIke L

12/17/2021 07:13:38 am

To get an accurate water delivery time a few variables are needed. System volume is just one of them.

The article has a chart that gives water delivery time based on volume, but I would use this as pass-fail guestimate and not a definitive calculation

https://www.tyco-fire.com/TFP_common/DryPipeSystems_Rev.pdf

Anthony

12/17/2021 08:08:49 am

No, you should have complete system, hydraulic and air data.

Alex

12/17/2021 08:12:19 am

Need more than that! System size and layout is important.

Casey Milhorn

12/17/2021 08:56:16 am

No, you cannot. System layout, psi of maintenance air, system water pressure, elevations, volume, etc. all come into play. Pockets of air will get trapped by incoming water, which actually aids in water delivery time. A tree system with a low center fed main with elevated branch lines makes the most sense to be the quickest for water delivery time, but I've never had the opportunity to play around with Tyco's water delivery calculation program to test that theory out. It would be fun to setup several different layouts and see what happens.

Franck

12/17/2021 09:51:22 am

I concur with all that have been said. The answer is no.
Well, it could be yes only if you have a very large system and you know by design it will fail.
But you won't be able to determine if this will pass.

In the good old times, NFPA was giving maximum volume limitations for dry systems with or without accelerators. But the aim was still to be sure to have water at the most remote point in less than 1 minute and the figures were quite conservative.

As indicated by others, the pressure differential between the water side and the air side my delay the activation of the valve. And this activation time need to be added to the necessary time for water to go through yur entire system till the most remote sprinkler.

Best practice : test from ITC at least once every 3 years!

sean

12/31/2021 06:29:50 pm

technically with a stopwatch, joking aside a simple field survey could get you a pretty close estimate.

do you not have access to the original design or testing information?

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Use Volume Only to Determine Dry Trip-Time?

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