Accidents happen, it's just a fact. Accidental system discharges are no different, but there are specific ways to minimize your chances of experiencing one in your system. Resulting from your environment or human error, Fire Protection expert Lee Kaiser explains some common causes of accidental system discharges, and how to avoid them.
Lee: "Problem number five. Since we talked a little bit about suppression systems, we're gonna go back to that and now talk about accidental discharges. This qualifies for cleaning agent systems, carbon dioxide systems, dry chem, water mist and even pre-action or deluge sprinkler systems. Accidental discharges as it relates to the detection and control system for the building. Why don't we want a system to accidently discharge?"
Audience: "It creates a huge mess."
Lee: "You say they give the gas away for free? Is that what you said?"
Dirty Environment and Dust
Lee: "No, that's not right sir, I'm sorry. They can be very expensive. So those are reasons we don't want accidental discharges, we really want to avoid them. One of the reasons, dirty environment, we talked about that. Dust burns off on heat exchangers the first time and we suggest cleaning off your heat exchangers. If you have an air handling unit in a space that's protected by a suppression system, housekeeping is going to be very important. That's one place we need to clean; the heat exchangers. Another place: having dust come into the space from the operations in the space, raised floors. What do we put under raised floors?"
Audience: "Smoke detectors."
Lee: "Well more common than that we put cables under raised floors. Those cable bundles get very dusty over time. Let's say I want to rip a bunch out, well I better disable my suppression system while I'm doing that. I'm gonna kick up a bunch of dust and because of my under floor smoke detectors, I'm probably going to activate one or two of those and maybe dump the system."
Audience: "That happened last week, very same thing. Moved some junction boxes around and set off the alarm."
Lee: "Did you use the abort switch?"
Audience: "Yeah, quickly."
Transfer from External Areas
Lee: "Very good. Thank you for saying that, we'll bring that up too. Transfer from external areas. When I first started getting exposed to data centers in my career I was designing HVAC for John Deere data centers. What's John Deere make?
Green tractors, right, you can't say red tractors. Green tractors get made in factories, factories have tools, those tools are smart and they need a data center to help run them. We would put data centers in those factories, except factories are dirty sometimes and once in a while we'd get some dust. Or it could happen that we'd get dust in the data center. We paid a lot of attention to room ceilings so we didn't get dust in there and that wasn't a problem. That could be an issue if you're not paying attention to that. It'd be another way that you could get an accidental discharge as far as transfer from an external area.
Human issues. There are probably more accidental discharges caused by dumb things that humans do than anything else. Release of refrigerant gasses: an HVAC tech is in there recharging your refrigerant circuits and he burps a little Freon into the air. Refrigerants look a lot like smoke to smoke detectors and we've had false discharges because of that.
Pipe welding is another story. Pipe welding and pipe braising. We were made aware of a situation where there was a pipefitter who opened up the raised floor, got down in there and he was running new copper lines for refrigerant to a couple of new HVAC units in the data center. They happened to have a suppression system and he did not disable the system. He struck his torch and started to heat up the pipe and get the braising filler going. Smoke went immediately to the smoke detector under the subfloor that was about 2 feet away, and it also went up to the detector that was above his head. We had first detection, second detection, and boom the system dumped. He didn't know what to do and that's the unfortunate thing.
We're going to talk about training here, but training the agent disconnect switch, the abort switch, and all those things are really important for you to know when you're working in a suppression protected space. I have actually a little sample to pass around. This is a little mock-up that we made so you could see some of these things that we're talking about.
Agent Disconnect Switch and Abort Switch
The first thing here is an agent disconnect switch.This gets wired in line with the releasing circuit so that I can physically disconnect the circuit. I'm gonna have a couple pairs of wires to it, one's the releasing circuit and another sets the power. I can power up the red LED and the green LED, when the green light is lit we're good to go. When the red light is lit, this means that the system is impaired.
Now this other thing over here is the abort switch. The piece the pipe fitter didn't know about. If he recognized that it was him that caused the activation of the system before it went off, he could have went to the abort switch and held it down if he was trained to work in that space.
This abort switch is a momentary switch. You have to hold it down for it to engage. The other thing we have here is a manual pull station. We'll talk about dual action pull stations. For you to actually discharge a system here you have to push in and pull down. By the way, there are keys here so you can go in and reset these and fool around a little bit."
This video is part one of a two-part video chapter on accidental system discharges. In the next segment, Lee will discuss the NFPA code that governs accidental discharges and the training to implement to curb their occurrence. To receive an instant notification when the next video is released, click here to subscribe to our fire protection blog.
Problem 1: How to Operate Your Fire Panel
- How to Operate Your Fire Panel: Alarm Signals
- How to Operate Your Fire Panel: Trouble and Supervisory Signals
- How to Operate Your Fire Panel: Conventional and Addressable Panels
Problem 2: Causes and Cures for Trouble Signals
Problem 3: Failure to Detect a Fire
- Failure to Detect a Fire: Common Causes
- Failure to Detect a Fire: Minimum Requirements and Performance Design
Problem 4: Causes and Cures for False Fire AlarmsFalse Fire Alarms: Where to Place Detectors