Ventilation

Inside a burning building is a dangerous place to be, for a variety of reasons: 1) heat, 2) smoke, 3) dangerous gases, like carbon monoxide (CO). It's important, also for a variety of reasons, to get all three out of the building.

First situation: food in an oven. This produces lots of smoke, but is often easily contained and extinguished. Still, the air will be filled with smoke. To help the homeowner, we set up a fan in a doorway and push outside air in, to clear the air. That's called PPV, or positive pressure ventilation. You put a PPV fan outside the door, such that the cone of air covers the door, and open a window in the smoke-filled room. (If you put the fan inside the door, some/much of the air you were pulling in at ground level would come right back out the door above the fan.) Assuming that the smoke has gone throughout the house, you open a window in one room at a time until the air is clear throughout the house.

Second situation: building on fire. Heat builds up, making the interior much more dangerous. Heat from the fire (as well as the smoke it gives off) rises, and collects on the upper floors, endangering occupants. While some FFs (from the engine company, often) prepare hose lines to go in and extinguish the fire, other FFs (from a truck company, often) can go onto the roof and cut holes to allow the hot gases to escape. This clears the air inside, and makes it safer for both occupants still in the building as well as the engine co. FFs about to go in. (In other situations, a fire can be "self-ventilating", meaning it burns through either a roof or wall, or breaks a window, allowing the heat/smoke/gases to vent on their own.)

Third situation: building no longer on fire. Even though the fire's out, there's still heat, smoke and gases inside. FFs need to go through the building, remove smoldering materials, and ensure that all hot spots are gone (so they don't reignite in the near future). To do that work, they either continue to wear airpacks, or completely ventilate the building so that it's safe to breath ambient air while they work.

Fourth situation: gas leaks, CO alarms, etc. These situations also require ventilation, in addition to figuring out and dealing with the source of the dangerous gas. FFs have hand-held meters to assist in determining the source of gas and in knowing whether ventilation is successful. (As a side note, sometimes the source is obvious; our instructor told us about a CO call, fortunately not involving fatalities, where residents of a row home decided to roast a pig in their basement. Not good.)

So we ventilate, to make things safer for occupants and FFs, during and after a fire, and to assist occupants in putting things back to normal.

Air Packs

Last night's training involved donning air packs.

There are a few steps involved in putting an airpack on. Some of these can be done in different orders, but my sequence was:

1) Put on the pack. It's like a backpack, with the air cylinder fastened to the frame. It's got a waist strap, too, so that the 30-40lbs of weight rest on your hips, not your shoulders.

2) Put on the face piece. This has webbing that wraps around your head, and 4 straps that you tighten to secure it to your head, and create an air-tight seal.

3) Attach the regulator to the face piece. In our case (MSA), the regulator starts off attached to a clip on the waist belt, and you unclip it from that and clip it into an opening in front of your mouth, (on the outside of the face piece). At this point, you should check your seal by breathing in; since you haven't opened the air yet, you should get nothing coming into the face piece around the outside.

4) Now, (before you run out of breath), turn on the air cylinder by reaching around the bottom-right side of the backpack and opening the valve. If you're mask is tight enough, air flows into the face piece when you breathe in, but doesn't leak out the sides. (These masks are positive-pressure, meaning it provides just slightly more than 1 atmosphere of pressure, rather than requiring you to pull air in via lung effort; this makes it safer in the case of a mask leak, meaning smoke won't come in when you breathe in.)

5) Now that you're breathing air, pull your hood up over the face piece, and put on your helmet and gloves. Done.

Now, do all that in 60 seconds. Yeah, it's about as hard as it sounds. The point of doing it timed is to make sure you're comfortable doing it, and can be ready in an emergency situation. Like the 60 seconds to put on gear, in real life, you'll most likely have more time than that, but you need to be comfortable with what you're doing.

Now, the frustration. I'd never touched an airpack before. Apparently, I was one of two or three in the class in that situation, and it just didn't occur to the instructor to ask. So I figured most of the above out by myself. Several things tripped me up along the way, but I worked them out as I went; the pressure was that each attempt was timed, and I didn't get to work my way fully through the process before we were told (as a class) to start over.

On the positive side, each attempt got easier, and on the try where I forgot my hood, I got everything else on in the 60 seconds, with a bit of fumbling around. So I'm pretty confident that I'll get it worked out for next class. And we've got a night off next week to be able to practice at our station as well. Just one more thing to master.

Two Calls At Once, and a Fire

So after a couple of sparse weeks, Saturday we get not just one but two vehicle accidents at once. Page comes in, I get to station, get suited up, E2 is full so I'm first on Squad. As soon as I get on, call comes over the radio for an ambulance, our E1 and another company's engine to a 2nd accident.

At this point, we're short a driver, so I and Squad's driver head over to E1, while another driver arrives for Squad, and the rest of the FF's in station split up for the two calls. Everything got staffed, and both accidents turned out to be easily handled and fairly minor.

Then Saturday evening, we get called for a trash fire. Apparently, folks at a local church had a cookout, and the coals weren't cold enough when they emptied them into the dumpster. The trash line took care of it easily, and I got to pack the hose away when it was over. (So far, for the record, that was the closest I've come to actually seeing flame in my illustrious, 4-month firefighting career...)