By Jim Nagle
How much is 500 pounds of air pressure worth to you? A penny a pound? A buck a pound? A million? The answer depends on several factors.
Location will certainly impact the dollar amount. During your morning gear check when the SCBA is on the rig and you have a cup of coffee in one hand, maybe it’s worth a penny or two a pound. But at 0300 inside a smoky building, that pressure could easily be priceless!
Experience has a lot to do with how much you’d be willing to spend on those 500 little pounds. For example, take someone who’s been lost in an IDLH (immediately dangerous to life or health) environment and made it out with just a few breaths to spare. Most likely that person would tell you that there is no dollar amount that can be attached to 500 pounds of air. I’m sure that firefighter’s family and colleagues would agree.
I was once guilty of not changing my bottle if I found it depleted by “only” 500 pounds. In Everett we use 4,500-psi bottles, so anything above 4,000 psi was acceptable to me. Recently, however, a fellow officer took me and my crew through a drill that demonstrated just how vital 500 pounds of air can be in terms of time gained.
The drill is very simple. First, grab some spare SCBAs and drain their bottles down to 500 psi. Next, don full structural firefighting PPE and the low-bottle SCBA. Then give your crew some task to accomplish around the station while on air. Make it something that will require some effort. We made good use of our drill by making the daylight savings time change on the apparatus-bay clock. It’s high on the wall, so some ladder work was required.
In the end, we were able to complete the job with time to spare. By my watch, that 500 psi provided me with about seven minutes of air. Keep in mind, however, that respiratory minute volumes of working or emotionally stressed firefighters can easily exceed 100 liters a minute, reducing that air time to about three to four and a half minutes of air. Remember also that 500 psi in a 1,200-liter cylinder is not the same as 500 psi in an 1,800-liter or 2,400-liter cylinder. Air pressure isn’t the same as air volume, so your sense of how much air is still available will vary with your gear’s capacity.
After the drill, I pictured myself in trouble in an IDLH environment, lost in a building, and looking for my way out. I thought about how I would need to stay as calm as possible to make my air last as long as possible while I searched for the way out.
I then imagined my vibra-alert going silent (a sign that my air supply was nearly depleted) and then my mask sucking up against my face. It’s a situation I never want to be in. But if I ever am, and you’ve got 500 pounds of air to sell, you need only name your price.
Jim Nagle is a captain and haz-mat technician with the Everett (WA) Fire Department, with which he has served 13 years.
