Since the device says " call 911," are you in the US? Or the UK? The device selection is a bit different.
There are a couple of different ways to do this, including wiring something in line, but I will leave it to others to discuss that.
If you’re in the US, the Leeo acoustic sensor would be the simplest way to solve the use case.
This is a plug-in device which simply listens for specific acoustic patterns and then send you a push notification. It also has its own IFTTT channel, which can be used to integrate with SmartThings.
It can recognize The US mandated residential smoke alarm pattern, CO alarm pattern, and the continuous tone used by most water leak sensors. I don’t know if your sprinkler alarm will fit one of those patterns, but if it does, but Leeo is a fast and easy way to get integration. I use this at my own house for some older smoke alarms which are not otherwise that worked.
List price for the Leeo is $49, but it quite often goes on sale for $29 if you want to wait for a sale.
There are certainly other alternatives which involve wiring something in line if for whatever reason the Leeo does not appeal to you. But if you do want to give it a try, it’s a simple as plugging it in and setting up the app and you’re good to go.
Am I correct in thinking you want some kind of notification if the alarm sounds?
Am I also correct in thinking that the alarm/bell is 18vdc?
If the answer to both is ‘yes’ then I would just connect a relay powered by the same wire that powers the bell and use this to connect a z-wave water sensor’s two wires together.
I use the relay/water sensor method to connect all sorts of things to smartthings.
After connection it is easy to get the water sensor to send a notification.
You are thinking about it way to much. the redbox on the riser that says potter is a flowswitch. There is two sets of contacts in it either normally open or normally closed. Get one of the zwave door sensors with an extra normally Open contact on it or pick up a Wireless Z-Wave Multi-Input/Output Dry Contact Bridge. It will tie in very easily. If you want something battery operated this is the zwave door sensor that runs on battery and has an internal N/O switch you can use to trigger on the flow Schlage RS100HC V N N SL Home Door and Window Sensor with Nexia Home Intelligence (Z-Wave).
Where the flex conduit enters the flow switch there is another knockout behind it that you can knockout to run 18/2 to into the flow switch. there is 6 contacts 3 on each side. Use the side not wired already for the bell. if you are using the battery powered door switch connect one wire to the “COM” terminal and one wire to the “Normally Open” terminal. Then match on the door switch. When the riser flows it triggers the Normally open contact into closed state thus setting off the door trigger.
You will need a tamper resistant torx key set cost about 5$ from any hardware store. These are torx with a hole in the middle. After you connect the wires you can push the plunger down with your finger it will take around 45 seconds for the alarm to sound this is to code so water hammer does not trigger false alarms. If you dont want to wake your neighbors goto your breaker box and turn off the breaker labeled fire bell then you can test all day long until you know its working. Might be a good idea to turn the breaker off anyways as it will have 110v running through it for the bell
I made a a quick one in paint it shows how the bell is wired you are almost going to wiring the same way all depends if you get a normally open or normally closed door sensor. If you get the Schlage RS100HC the contacts are Normally Open so its wired how I show. If you get a Normally Closed contact you would just move the normally open wire to the center post which is normally Closed. If you need instructions on the door sensor youtube has a few but its pretty straight forward just a spot for two wires.
The oval circle in the middle is the plunger you can push with your finger to test.
You would name the door sensor something like Fire Sprinkler Flow Switch. And set it up like any window/door switch if it opens you want to know as it should always be in closed state.
You wont damage anything. Like I said you will need a set of tamper proof torx set to unscrew the two screws that hold the flow switch cover on these are normal torx but with a hole in the center. You will not be taking anything off the pipes its designed to open up. Unscrew them the covers pulled straight off. It does have a rubber gasket so a small tap will get it free. pull straight off and you might need to turn it to get it around the drain pipe coming down. But once its open you push out the knockout and run your wire inside. The terminals are Phillips screws put them on the correct terminals then put the cover back on and you are done. There is no water in this area so just take your time you wont damage anything. Again turn the fire bell breaker off just to be on the safe side while you work.
Sorry it took so long to get back to you. Being you have a fire sprinkler system in a residential home I assume you live in California. I might be able to help you out. What area are you located in. I work out of Corona CA but cover all areas of southern California at any point. So if I am in the area I can swing by and give you a hand and at least get the wires hooked into the flow switch for you and leave them hanging.