Sequence of Operations for Closed-Loop System?

5/6/2022

We are trying to complete system testing for a closed-loop system and a waterflow alarm is not reporting back to the fire alarm panel.

Is there a good sequence of operations for a closed-loop system?

More specifically, what order of events needs to happen when a sprinkler activates?

Thanks.

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4 Comments

Alex

5/6/2022 06:13:33 am

Hi,

These systems are tricky and should be phased out on all new construction. BUT, for your question:

1. Are you sure the water flow still works? I cant stop to think that if it was constantly causing false alarms that someone would tamper with it...

2. The sequence of operation remains the same as any other looped or branch system. When you install a combined system, the closed portion is downstream of your water flow. This means that the water is simply circulated and flowing throughout the distribution piping but not the riser/FCVA. Therefore, not tripping the water flow [NFPA 13 (2013) 7.7.1.7]

You also do not need to worry about any mechanical equipment during the fire. If designed properly, every sprinkler has a direct path to the water supply. Meaning, there cannot be a pump or piece of equipment between the head and riser. [NFPA (2013) 7.7.1.2]

I hope this helps.

Thanks,
Alex

Glenn Berger

5/6/2022 08:17:07 am

For closed-looped systems, I have provided a pressure switch. During the normal operation of the closed looped system, the pressure remains constant. On sprinkler activation the pressure switch can initiate the "water flow" alarm and then the follow-on notifications..

Jesse

5/6/2022 08:24:03 am

Agree with both Alex and Glenn. Not a fan of closed-loop systems though we have several within our service division.

1) check the flow switch. It may have failed or been disabled.
2) Consider a pressure switch

Brian Gerdwagen FPE

5/6/2022 09:26:57 am

I am not a fan of pressure switches in wet systems. But you can use a traditional vane-type flow switch with a check valve above the flow switch to protect it from the turbulence of the circulating system.

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Sequence of Operations for Closed-Loop System?

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