During the MCFP Virtual Conference series, expert Lee Kaiser, covers how to run a test of a sequence of operations for suppression systems. In the video below, watch as Lee dives in-depth on what is required for inspection in both integrated and cross system detectors.
I'm going to explain the sequence of the suppression system release but also show you the opportunities that you have to do integrated systems testing. I'm going to explain the concept of counting zone or cross-zone release.
Who's heard of cross-zone detection? A couple of people. When we say cross-zone detection, what we're trying to say is we want confirming detection that there really is a fire and not just a false alarm before we release the suppression system into the protected space. Back in the day, we used to call it cross-zoning because all we had available to us from a technology perspective were zoned suppression system panels, or conventional, they're the same word. They use zone circuits, so we call them cross-zone. This means that we need to have both zones, meaning circuits activate, both detection circuits activated before we will release the systems. If one false alarm detector goes off, then we don't release the agent. It takes both of them before we will release the agent.
We can cross zone by zones or we can cross zones by detector type. We'll show you some examples of using different detector technologies where we sense the fire in two different ways before we release the system. On addressable panels, officially we use counting zone because with addressable panels, there is a discreet address for every device and we can count; one detector, two detectors, now we know to release, so we use all these terms sort of interchangeably. I wanted to give you a little explanation about that. For conventional cross zoning, just to show what that looks like, we have a conventional suppression control panel and we have two different initiating circuits. Circuit A, we have some detectors connected to it and some detectors connected to Circuit B, so it takes a detector on each circuit before we'll release the system.
Since I'm a fan of animated slides today, we have Freddie the Fire show up, detector on Circuit A comes in, another detector picks it up, stay at first alarm until we get a detector at Circuit B, and then we get second alarm, first alarm, second alarm, and then we can release the system.
It changes for counting zone with an addressable panel, we just count the detectors. Freddie Fire shows up, we get one detector, first alarm, get a second detector, second alarm. Now we can release. With that counting zone in mind, let's build the suppression system out and then we can watch the sequence.
We've got an addressable suppression control panel or releasing service fire alarm panel, both same thing. Here, we've got our signaling line circuit and at least two detectors. A suppression system for counting, we've got to have two detectors. We're going to have a number of circuits, but one is just the building fire alarm system. We add a couple of things to make it a suppression system. One thing is we'd add is a releasing circuit connected to our suppression device. In this case, it's a clean again tank, valve and a control device. When that control device opens the valve, the gas is going to flow out of the piping to the nozzle and then into the room.
Releasing circuit, any time we have a releasing circuit, an output circuit on a suppression system, we're going to have a disconnect switch. The code requires us to have a disconnect switch. It's like a circuit breaker for that switch. I can put a key in it and turn the key to physically disconnect that switch so we don't have an accidental activation of the system when we're doing testing or other activity in the space that could cause an accidental release to the system. Another thing we've added is a manual release station, so this is a pull station intended to dump the system. If I'm in the room and I see a fire happen, then I can go to a pull station and activate the system to discharge to extinguish the system, so I can have options to do this electronically like we're doing with a pull station or mechanically with another device. We're going to always defer to the electronic way of doing things.
When we have smoke at the first detector, we're not going to release the gas. That's not the point. We're going to wait for a confirming detection but like a normal fire alarm system when we have smoke at one detector, we're going to activate the building fire alarm system, so it's going to go off. Whether it's controlled by the releasing panel or we send a signal to the building fire alarm system, the fire alarm in the building is going to be going off. When we let the smoke build, then we get smoke at a second detector, a number of things are going to start to happen before we release the agent.
First off, we're going to start a timeclock and that timeclock's going to give us a 30-second pre‑discharge countdown before we release the gas. During that time, inside the space protected by the clean agent, we are in code required to have a pre-discharge warning signal, so this is a distinctive audible signal that's happening, warning people inside that space that the system is going to release. In this case, we're going to activate an electric bell inside the room and then another couple of things are going to happen.
We're going to use outputs, relay outputs from the panel, to start to power down the HVAC, close dampers, and maybe shut down the power to electronics through the emergency power off system using shunt-trip breakers. This is where I want to highlight our opportunity for integrated systems testing because the unit that's sitting there is not a life safety system but the shutdown of it through the suppression control panel, that's the life safety function. This is where we need to do a new installation of integrated systems testing, and we're going to repeat that over and over as we go through these different fire suppression sequences.
During a 30‑second countdown, is where we could use an abort switch if one was installed. If we have an abort switch installed near a door in our room as the system goes off, and we heard the pre-discharge warning while we're in there and don't see smoke, don't smell smoke, and don't see flames, maybe I'm going to go to that abort switch and I'm going to press the abort switch to stop the system from releasing to give myself more time to investigate why is the system going off. Maybe I did something that caused it, maybe it's a contractor in there, maybe the HVAC guy burped a little bit of refrigerant out of his reclaimed kit, and that refrigerant always looks a lot like smoke to a smoke detector. If he caused it, he's trained because he's working in a room that you've trained him to work in, he can go and use that abort switch and stop the system from dumping.
There's a lot of different ways that abort switches can work. When we have the system stopped through an abort switch that would be our opportunity to reset the panel, so we're usually going to phone a friend at that point, pick up our cell phone and have somebody else come into the room to reset that panel for us. They've got to know how that system works too so that panel gets reset. If it stays and doesn't reactivate, great, we've avoided a discharge. Why do we want to avoid discharges? It's costly. Fire-related discharges are one time but accidental discharges, we want to avoid those.
Let's say that the 30-second countdown expired, then what happens next in the sequence? The releasing circuit's going to activate, the valve is going to open, the gas is going to discharge into the space, and the last thing we're going to do is activate another circuit for a discharge alarm. This is a visual alarm on the doors outside of the protected space, which indicates anybody coming into the room that the system has discharged. Usually, those strobes will be labeled. If this device is flashing, FM200 system has discharged inside the room. If you're inside the room when it discharges, it's going to be pretty obvious that the system has discharged. You won't need an additional warning that it went off.
Okay, so now I talked about cross zoning, but I do want to break that theory on this and say that you can use a single air sampling smoke detector to do confirming detection. We typically talk about a Vesda detection when we're discussing this. Vesda in our technology spaces gives us very early warning fire detection so we can see smoke at really low levels well before we get to a life safety risk level of smoke, and we can then start to work in the space and deal with what's causing that smoke, and so that's a concept of very early warning fire detection. I also mentioned that it has a high immunity to false alarm, so very reliable detection tends not to false alarm and in some spaces, it can be cost effective depending on the size of the installation and the number of detectors needed for that space. We can install Vesda as cheaply as we can install spot smoke detectors, especially when we factor in the total cost of ownership of servicing spot detectors on the ceiling above valuable electronic equipment that we can't access, so that's one reason we might use Vesda detection.
If we're going to do cross zoning, we need to have two Vesda detectors, but I want to use this section to tell you that Vesda is so reliable, we don't have to use two detectors. We're just going to use the multiple levels of smoke warning notification that the Vesda system has before we release the system, so Vesda detectors give us four levels of notification of smoke; two pre-warning levels and two warning levels, so pre-warning levels are alert and action. When these signals come in from the detector, we don't activate the fire alarm system. We wait. We may get a supervisory signal at the panel. That's usually what we prefer to do is generate a supervisory signal at the panel so that you're warned that there is an off-normal condition in your building and then you can go to the Panel C, that's a Vesda detector, and go to whatever room my Vesda detector is in and start to investigate what's causing smoke in that space.
We won't go into a fire warning until we get the fire one and fire two. Fire one's the first level of fire warning notification. When we design Vesda detectors, we design to make that detection equivalent to what a spot smoke detector would first go off in the space, and so that's our first life safety warning of smoke build-up in the space, it's fire one. Fire two is another less sensitive to smoke setting and we'd wait for us to get to that fire two setting before we'd release the system, so that would be our confirming detection when we're using a single Vesda detector.
Let's show you what that looks like in the system sequence. We've got the same clean agent system depicted here is what we did the last time, except that we've replaced the spot smoke detectors with a single Vesda detector. When we have a little bit of smoke, we maybe come to that alert warning and we come in, we look at our panel face, and we'd have a light lit up for supervisory. That would be our indication there. Our building fire alarm system would not go off at this point. We'd just have a supervisory on our dialer for our panel would send a signal off site. They'd say "hey, this building's in supervisory."
You'd have a couple of different ways to know that you had a supervisory on your panel and it would give you time to do that early warning investigation. Sometimes, this alert, where we had this low level of smoke can be hours or even days long, as whatever is overheating continues to overheat and just makes that low level of smoke, so you may have a lot of time to investigate. One of the tools I really suggest for people that use air sampling in their buildings is if you want to know about those early indications of smoke, have a thermal imaging camera available, and there's some pretty economical ways for you to purchase those, and you can go out and look at your electrical equipment in those rooms and see what's overheating. That's probably the source of your smoke inside your space.
If smoke continues to build, then we get to the fire one level where that would be our normal fire alarm activation, the evacuation sequence; the horn strobes in the building would be going off. As fair continues, smoke builds, then we get to fire two, and then our system-releasing sequence would start from that point. The pre-discharge alarm would activate inside, signaling the pre-discharge warning time period. Our timeclock would be counting down for 30 seconds. Our relay outputs would all activate to prepare the room for discharge and at the end of that 30 seconds, then we'd have a system discharge and our discharge alarm would be going off. We'd use that single Vesda detector in the multiple levels of smoke warning to build that confirming detection that we need.