What's the purpose of Alarm check valve using in Sprinkler system? 2

[Sittipon99]

Hi , i'm just curious the reason to have alarm check valve in the system. I heard someone say " to reducing corrosion ,to avoid unwanted alarms " .
Dose anybody have other reason to install alarm check valve ?
Thank you for helping.

 

[MGXFP]

In the old days, the alarm check was used to activate the water motor gong. When the clapper opens upon water flow, it exposes a port or ports that allow water to flow through them and associated piping to rotate a water motor gong.

A check valve is still a good idea in modern systems. During work on other risers it allows them to remain in service without having to drain the other systems or turn them off via control valve. My two cents is alarm check valves are obsolete now that water flow switches are available. I suppose one could use the alarm port to activate a pressure switch instead of a flapper.

 

[UFT12]

Check valves on the riser are meant primarily for disallowing the system to drain in case there is need to empty the system upstream the check valve. That would prohibit fresh oxygen to enter the system and therefore corrosion rate within the pipe is reduced. An other consideration may be to save resources as for large systems the amount of water may be considerable, especially when talking for a system with many risers.

Nuisance alarms may be avoided but not directly through the use of the valve rather a retard chamber which is attached on the valve trim (optional). There may be false alarm through reverse flow on a flow switch in case there is no check but I am not sure whether such thing may occur in reverse.

In general, an alarm check valve is a multi-purpose vital component to a sprinkler system. It is equipped with trim (an assembly of valves, gauges, drain etc) that allow easy inspection and maintenance of the system. See the documentation of various manufacturers such as Tyco, Viking etc.

 

[Sittipon99]

Thank you for helping me.
You both help me a lot,sir.