During the MCFP Virtual Conference series, expert Lee Kaiser, covers water flow testing of wet sprinkler systems. In the video below, watch as Lee dives in-depth on what is required for the testing of wet sprinkler systems.
Video Transcript:
Water flow devices in our sprinkler systems. We have two types. We have devices that send an audible signal out to warn people outside of our building that there's a water flow condition inside the building. This also notifies the fire department as they arrive so they hear these bells going off, and they'll know there's a water flow condition in the building. There are also water flow switches inside the system that send a signal for our fire alarm panel to let us know the water flow condition in there.
This device is on the outside and the water flow alarms need tested on a quarterly basis. Four times a year, because they're exposed to the outdoors and many things could go wrong out there, so they need to be tested four times a year. Things we look for could be a water motor gong, or an electric bell on the outside of the building.
Indoors, our pipes electric water flow switches need to be tested twice a year. To show you that, I've got a couple things on the slide. I've got a picture of a vein-type water flow switch, which is what we're using most frequently in new installations. And then here I've got a show-and-tell item. This commercial riser assembly. This is something that's getting commonly used and it shows a number of these components that we do during semiannual testing.
This would get installed to establish a wet sprinkler zone inside of a building. We have a valve with water coming into this side and go past this device. This is the vein-type water flow switch and you can see the paddle. When you'd open it here, that's the paddle that would operate. Water flows past it and it would move to engage the switch inside of here where we'd have fire alarm wiring wired. When you see that switch move, we know we have water flow in our building, to set off the fire alarm system, and set off the water flow alarm device on the outside of the building. Water would go on past this gauge so we could see the static pressure and the flow pressure, and it would go out the pipes into the sprinklers there.
Off to the bottom here, we have this pipe cap to this valve. This is officially out of code language, this is an inspector's test connection valve from the manufacturer that calls for this test and drain valve. It can be put in either the off position, where this ball valve is or it can be put in the test position for the semiannual testing, where it's open. It's an open valve but it's open to this orifice position. So once a year, we need to test for this water flow switch. It needs to alarm for the flow of a single sprinkler. This this orifice size in here corresponds to the smallest sprinkler in my zone. So these are probably 5.6 K factor sprinklers. Probably a half an inch orifice, so this is what we have here. It has a half an inch orifice. So we're testing whether or not this flows or opens up, engages for just the flow of one single sprinkler. The last position is the drain position and we put it into drain to get a full port ball valve and we can drain down that riser.
The last thing to highlight here is this sight glass that's built into the test and drain valve. That's how the tester could visually see is there water flowing because they'd be looking for the air bubbles going past that little window when we're doing that testing. We're going to pass this around. It's a little heavy. Don't drop it on your toe.
To do that testing, the tester is going to look at the gauge on that riser and record the pressure at static conditions where there's no water flowing and at flow conditions after water flow has started. They'll record what that pressure drops down to. Open the inspector's test connection valve, check for water at the test flow outlet or the sight glass and then record how long does it take for the fire alarm panel to receive the signal from that water flow switch and generate and alarm. That sequence has to happen within 90 seconds. So that's what we're measuring for. And again, we measure that on a semiannual basis.
We have our testers reinforce it, and it may take more than one person to do this. We have one person at the wet riser so they can monitor the gauges. Another person at the inspector's test connection valve to open the valve when told to over the radio and they either observe the flow at the sight glass or outside the building. And then another person at the fire alarm panel to verify receipt of that signal and run the time clock that they get it within 90 seconds. Depending on your arrangement, you may not need three people to do this test but it's just one place where you may need more than one person.
Another test that flows water in a system is a main drain test. This is an annual test which flows water through a big discharge valve in a system called a main drain. It's used to verify the adequacy of the water supply to the building. The steps for that test is to locate the drain valve, record the static pressure when the valve is closed when no water is flowing and then record the flow pressure when we've open up that valve and there is water flowing. If we see more than a 10 percent reduction in the flow pressure from our originally recorded value, we record that flow pressure. Then we know that we've probably got a problem with the water supply to our building. It may not be inside our building. It may be out in the street in the city water main. So we need to maybe work with the water company to figure out why we have that reduction in the flow pressure when we do that test. Again, this is an alarm check valve here with a tap for the main drain valve. This is either an inch and a half or a 2-inch valve that goes outside the building and on the outside, this is where that water discharge is.
This brings me to some design recommendations for tests that discharge water. Understand that if you're a designer, the systems that you're specifying are going to be tested. And every year there's going to be flowing water. So we need to plan for that water discharge as part of the design.
Where do we locate that inspector's test connection, the main drain, even fire pump flow testing? Where's that water going to go? Best practice is to discharge all the water outdoors while being careful we don't damage any landscaping that's part of the facility or avoiding water freezing on the walkways in wintertime. Maybe, our only option to avoid that is to do testing in non-freezing times.
If we have to do indoor discharges, this is my personal recommendations for arranging for that. I suggest that you connect to at least a 4‑inch diameter storm or sewer connection depending on your plumbing codes and what they allow you to do. It can't be a direct connection. If it needs to have an air gap, then I suggest not just to a floor drain, I suggest having your 4-inch pipe come to a P trap and extend off of that a standpipe with at least 48 inches of pipe so that when you discharge into that, you've a chance to attach the water flow to the pipe wall and it will move through the trap easier without backing up and flowing out. So don't just go to a floor drain, have a standpipe to your drain connection.
For locating the inspector's test connection, the code says, NFPA 13 in this case, says that the location must be accessible. You need to be able to get to it and discharge to a location that can accept it. That's the specifics they are looking for in the discharge location. It just has to be able to accept it. I'll show you this picture in my past life in building sprinkler renovations as we've been trying to add sprinklers to buildings that don't have them. One of my only options a couple times was to a janitor's mop sink. Expect the flow of that sprinkler system test to be about 30 gallons a minute. And many times we were unsuccessful doing that and we had to redo the drain locations. It's hard to guess whether or not that's going to work. I'm just going to tell you to avoid it as a point of personal experience.
The other thing about inspector test connections, the code says that it can be attached to any point downstream of the water flow alarm. That riser assembly that we just passed around, if you look at where the water flow switch is to where the tap for the drain is, it's only about 6 inches apart.
Now that's allowed by code but a recommendation that we like to make for you designers is show your inspector's test connections as far away from that water flow switch as possible. There's two things that you're going to gain by doing that. One is as water flows through more piping in the system, you'll be able to reveal issues of corrosion inside of those pipes by flowing water through more pipe which may contain some of that rust and scale and corrosion-related debris. So you'll be able to see that in the discharge water. Two, we are aware of some buildings out there that have a lot of trapped air. As that air gets trapped up in the upper space of that piping network, as the water pressure comes into the system and fluctuates, it will start to compress that air and the system pressure will build up and at about 175 psi, maybe a little bit above that, that's all the greater pressure that these sprinklers are generally rated for and some buildings have had sprinkler systems burst.
One way to combat that buildup and pressure in the system is to have that inspector's test connection at the end of the system and then that will help lower that pressure every time you do testing. So now that's all wet systems. Right? Dry pipe systems, we're going to talk about pre-action system valves here in a little bit. Those inspector test connections must be installed at the end of the systems. So understand that there's a distinction there.
