In this video I went into detail about how a wet alarm check valve works (utilizing an excess pressure pump to prevent false alarms). I removed the alarm valve faceplate to show what the inside of an alarm valve looks like, and explain in detail how the alarm valve trim is piped together. I'm unfortunately kind of clumsy when it comes to picking up my phone on the tripod and accidentally stopped the video multiple times and most of the time I didn't even notice and was just talking to myself for 10 minutes without recording. So if the cuts seem kinda weird... its because I was backtracking and trying to figure out where I left off when I was explaining something. I honestly don't have much a plan going into these video's, there's certainly more that I could talk about but I thought this video would be best for 1st or 2nd year apprentices who don't quite understand how an alarm valve works or how all the trim fits together. I apologize I sometimes go off on a tangent and start going off topic, but I do mean well. Where I live, my province still uses NFPA 13 (2013 edition) and NFPA 25 (2014 edition) so any code references I might refer to are specific to these two code books.

If you're interested in how to perform a 5 year, 2-hour 150psi hydrostatic test on a fire department connection, I made another video in the same building/system (which is why you see a test connection on the ball drip in this video). Click on the link below for how to properly perform the hydrostatic test:
   • 5-year 150psi 2-hour Hydrostatic Test...  

00:00- What is a check valve
01:28- Internal Inspection of a wet alarm check valve (all ports explained inside and out)
06:23- Water Supply port (what gets installed on the supply side of the Alarm check valve)
09:13- Strainer and excess pressure pump (what is a strainer, where does it go?)
10:40- Excess Pressure Pump Discharge check valve (why is it important?)
11:23- System side trim downstream of excess pressure pump discharge check valve
12:05- How to pump up a sprinkler system with a MANUAL excess pressure pump
13:50- What is a relief valve?
15:26- Why do we close the Excess Pressure Pump supply/discharge shut off valves after pumping up the system manually?
16:40- Backflow/failed check valves? How do I know my check valve doesn't hold pressure?
18:50- Difference between a MANUAL vs Automatic Excess Pressure Pump
21:04- Pro's/Con's to automatic excess pressure pump
22:13- PS120 low pressure supervisory switch (what is it, why is it there?)
24:00- Order of operations- What happens when a sprinkler head fuses and system drops?
25:50- PS120 low pressure supervisory switch (why is it important? what pressure do I set the signal to come in at?)
29:00- If I have an automatic excess pressure pump, where would I want to set the PS120 low pressure supervisory signal to come in at?
33:00- Draining the wet sprinkler system and activating a low pressure supervisory signal
34:40- PIV (post indicating valve)
35:36- CLOSE UP OF WHITEBOARD showing all trim on wet alarm check valve
35:43- Visual/close up walkthrough of wet alarm valve trim with drawing to follow along
37:10- Bleeder valve (what is it? where would I install it? Pro's/Cons for a bleeder valve)
38:53- Excess Pressure Pump Discharge Check & Discharge Shut-off valve (what order should I install them in and why?)
42:52- What happens during a waterflow condition (i.e. a sprinkler head fuses)? How do the pressures change on the wet alarm valve? Where does water flow in the trim piping when a sprinkler head fuses?
48:38- What is the "alarm test valve" (normally closed) used for?
51:50- Visual/close up walkthrough of wet alarm valve alarm line/intermediate chamber trim with drawing to follow along
54:20- Restricted Orifice on the alarm line (why is it important? Why this causes false flow alarms? How to fix it? Best practice for installation)
63:03- sorry my video cut out and I lost track of where I was and for some reason I thought it got cut off on the system side port so I picked myself back up from there.
64:50- I ended up explaining why there is both an alarm test valve and a 3-way test valve on the alarm line.


31:52 Sorry I made a mistake in my explanation- if you set the PS120 to come in at 150psi but you only pump up your system to 140, then the supervisory signal will just always stay on (I said in the video it will never come on, my mistake)
63:03 Again sorry my video cut out half way through explaining the 1/2" relief valve DOWNSTREAM of the excess pressure pump discharge check valve & downstream of the excess pressure pump discharge shut-off valve. If you are doing a new installation, please remember install this as it is actually a very advantageous relief valve to have installed on the system.