ALUMINUM AND WIND SIGNATURE
I enjoyed “Steel vs. Aluminum Ladders” by Raul A. Angulo (Tool Tech, April 2012) very much. I found it to be well thought out and very fair to both sides. There is no “but” coming here; however, I would like to offer an “in addition.”
Regarding wind signature or wind load, aluminum requires much more material bulk to achieve the same strength. This creates a larger cross section to the elevating section and on any given day catches way more wind, which is added stress to the ladder, turntable, and all the pivot points and connectors.
I worked for 20 years in Whatcom County, Washington, rigging and hoisting loads with up to 500-foot cranes at various refineries. I always had my ESCO riggers handbook so I could check wind loads and the leverage factor, depending on how much stick we were flying. My personal concern is that aluminum ladders catch more wind, and that translates to less load.
The ESCO handbook (it used to be free at cable shops) shows “miles per hour (mph) equals pounds charts” and also leverage charts similar to those shown on the base of your ladders. It is a factor in crane safety and load limits. How big a factor it is needs to be determined by the firefighters involved. I do know that “pipe” fabricated lattice work booms were a lot nicer to work with on windy days.
I am a volunteer firefighter who has served on apparatus committees and am now retired from the refinery gig.
Steve Erickson
Training Officer
Lake Kacheese (WA) Fire Department
IT’S ABOUT REDUCING EMISSIONS
I read Chris Mc Loone’s July 2012 Editor’s Opinion. I do not agree with the tenor of the message. It seems as though he and many others in the fire service have forgotten the real reason that the diesel particulate filter (DPF) is on the diesel engine-to reduce exhaust emissions and, more specifically, to reduce firefighters’ exposure to diesel particulate emissions. Diesel particulate has some very nasty, toxic, and carcinogenic chemicals attached to it. It is not just elemental carbon soot. Furthermore, most diesel particulate is less than 10 microns in diameter, which means it goes deep into the human lung, essentially bypassing the lung’s natural filtration system.
I can speak with some expertise on the subject of DPFs. Early in my career, in my position as senior engineer with the Los Angeles (CA) Metro, I managed a project with the California Air Resources Board (CARB) where we installed the first of what was then called a “catalytic trap-oxidizer” on a bus operating in Los Angeles. That bus only ran for about two weeks before the “trap” became plugged; the engine shut down; and, yes, the naysayers were quite pleased; but that was 1983. Since that time, much development has occurred. Companies like 3M, Donaldson, Corning, Cummins, Detroit Diesel, Caterpillar, and Johnson-Matthey have invested millions of dollars in development.
Additionally, I can tell you that today I operate about 400 Cummins ISM powered transit buses with DPFs and have done so since we first began taking delivery of them in early 2008. I can assure you that stopping and starting 500 times each day is a tough duty cycle for a DPF. Although they have not been without a few problems during the past few years, we have learned how to maintain them like any other new technology, and their reliability is excellent.
I was very pleased to read “Aftertreatment Regeneration and the Fire Service” by Brian Chaput in the July 2012 issue, essentially saying that DPFs require some additional maintenance. But, nowhere did he make any reference that the engine’s reliability was adversely affected. In my conversations with engineers at the diesel engine manufacturers, it’s their opinion that fire departments tend to buy engines that are a lot bigger than they really need. Operating a truck that has an engine with more than 500 horsepower and weighs less than 50,000 pounds results in a situation where the engine “never breaks a sweat.” Thus, the average exhaust gas temperatures are low and do not promote the passive regeneration process.
Consider this question: What if the truck ran out of fuel while pumping? Who is responsible? Would it be the manufacturer because he did not install a larger fuel tank? I think not. It would be the responsibility of the truck’s operator to make sure the truck had enough fuel. The fire service problems with DPFs remind me of a story I once heard about the guy who took his new Model A Ford out for a drive. When it ran out of gas, he said: “This never happened to me when I had a buggy whip.”
At this point in time it is unclear what the United States Environmental Protection Agency (EPA) or the CARB will ask the engine manufacturers to do with DPF-powered fire apparatus. For the sake of the firefighters who are exposed to diesel exhaust, whether in the apparatus bay or on the fireground, I hope they say maintain the equipment like the manufacturer recommends and quit whining.
I get the message from some people I have spoken to in the fire service that since the EPA “forced” this on us we must therefore be against it. My response to that is: It’s not so bad being called a “tree hugger” and a firefighter in the same sentence.
Let’s remember who we are protecting here and why. I think Ulysses S. Grant understood the reason for his success when he said, “Feed the horses, feed the men, then feed yourself.”
Although the fire service has been my “other” job for the past 15 years, in my career I have prepared the technical specifications for many types of fire apparatus, transit buses, light rail trains, and diesel commuter rail locomotives. Also, I have more than 30 years testing and measuring the emissions from diesel engines.
Vince Pellegrin
Chief Operating Officer, Metro Transit
Minneapolis, Minnesota
