ASK ERNIE - ”The Apparatus Maintenance Expert”


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08/04/2013 -

What is regeneration? (Part one in the regeneration series)

First, you need to know what requires regeneration. Let’s start with the knowledge that EPA mandated a change in 2007 that set newer diesel exhaust emissions to a level MUCH lower than was current in 2006. To do that, a wall-through ceramic “filter” was placed in the exhaust pipe in place of the muffler. The diesel motor also underwent many engineered changes to lower the production of diesel smoke/particulate emissions. An important part of the lowering of soot production was the mandate to use much lower sulfur content engine oils (CJ-4 or CJ-4+) and fuels (ultra-low sulfur diesel fuel).

Note: the diesel did not magically cease the production of soot/smoke. The produced soot/smoke/particulates is now captured in the DPF (Diesel Particulate Filter) and is stored until the filter becomes impacted (filled) to a level that requires a burn off of the soot through a process of “Regeneration.” The regeneration process can be accomplished while driving down the highway under heavy load ( highway trucks ) or by the process of automatic or manually activated options dependent upon a myriad of conditions.

Regeneration is accomplished with the motor operating at an elevated RPM and having diesel fuel induced into the exhaust stream and burned resulting in the generation of extremely high temperatures, thus resulting in a burn-off of the stored soot in the filter. If a call comes in and you need to respond, simply tap the brake pedal or throttle and the motor will return to idle and you may respond as usual. Once back at the station, you should be able to restart the process and go to completion. What then remains in the DPF is a very fine ash residue. After many of these regeneration processes, the filter will become so filled with ash that the filter must be removed and cleaned through an expensive process. Once cleaned, the DPF is reinstalled and ready for another run. Once the process of regeneration is started, it may take up to an hour to complete.

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My 2010 engine has a regeneration system on it. Can you explain how it works? (Part two in the regeneration series.)

I sure can try. But, first we have to go back to the EPA 2007 mandated upgrade to the emissions systems on diesel engines. The new system engineered and incorporated into the new 2007 engine consisted of a Diesel Particulate Filter (DPF) and a burn-off system. The DPF replaced the muffler and consists of a multi-cell ceramic wall-through filter that traps all (98 percent plus) diesel particulate (soot). Once the DPF becomes plugged with soot, it sends a pressure transducer indication of DPF saturation by excessive back pressure indication. Heating the exhaust stream to extremely high temperatures burns off soot. As the soot is burned off, it creates ash, which is compacted in the exit end of the filter. As the filter becomes more compacted with ash, the regeneration process will be needed more and more often. The DPF system was designed for use by the Over-the-Road (OTR) trucks, which generate high exhaust temperatures as they simply drive down the road, hour after hour, day after day. The result is that the need for regeneration is rarely, if ever, needed. Because fire apparatus operate in vocational service, we do not operate the engine at a sufficient high exhaust temperature to continually burn of the soot. The result is that we require a “Parked” regeneration burn off on too regular of a basis.

Next, the EPA in 2010 mandated the use of a second unit (catalyst) that is added behind the DPF and induces UREA/SCR/DEF or which is technically synthetic pig urine into the exhaust stream to reduce remaining pollutants from the exhaust stream. That means your 2010 diesel apparatus of 10,000 GVWR or greater has this system added to the 2007 DPF. An additional computer to control the dosing of the exhaust stream, multiple additional sensors, a dosing injections system, a Urea tank with heater and mixer, and the added catalyst “muffler” looking device. The 2007/2010 emissions controls have become so problematic to efficient emergency responses that a change was recommended by FAMA (Fire Apparatus Manufacturer’s Association) for diesel powered fire apparatus and ambulances asking the Fed EPA and CARB to exempt fire service apparatus from the mandates of the DPF and Urea systems. While exemptions recommendations to engine (motor) manufacturers, full exemption from the emissions controls did not allow customer/manufacturer removal or altering of the DPF and Urea systems. (See part three.)

I understand that EPA has made changes and some exemptions available to the fire service. Is that true? (Part three in the regeneration series.)

The simple answer is “Yes.” That being said, all emissions systems components of any year of manufacture must remain in place and be maintained to the original manufacturer’s specifications. The 2007 DPF systems and the 2010 DPF/Urea systems get some help. FAMA and Mr. Lackore of Oshkosh Corp. testified and recommended to the EPA, several recommendations. The most promising recommendation is directed to the motor manufacturer to change the software to allow slightly higher generation of emissions that create less soot, extending DPF burn times. Secondly, motor manufacturers are asked to change software and install a switch that will allow for an “on-demand” activation of a regeneration burn, prior to any dash warning lights being activated. Apparatus will then be able to be placed on a ‘schedule’ to burn off soot buildup in the DPF on a regular basis so that there is no derate or shut-down of the motor during emergency responses. The full article/white paper can be found here: http://fama.org/pdf/engine_topics/FAMA%20DPF%20and%20SCR%20Guide%20130102.pdf.

My platform moves irregularly when the temperature changes, why is that?

Most common to changes in operating characteristics of the platform (or any aerial) with regard to temperature changes is the changes in viscosity of the hydraulic fluid. You may consider that the aerial will not operate as designed and intended until the fluid warms to normal operating temperatures. If the fluid can be brought to normal operating temperatures during cold temps, the operating characteristics should be the same. That being said, ALL circuits within the system must be brought to operating temperatures through use of ALL the circuit functions. If the fluid temperatures exceed the manufacturer’s recommended fluid temperatures, a fluid cooler may be in order. The manufacturer should know where the aerial will be used and build the aerial to function in all operating environs.

Aerials that have acquired many hours of service may have issue with the electrical/electronic systems whereby external/internal temperatures can change continuity or resistance in the electrical/electronic controls. The most common issue with this type of situation is “Grounds.” Diagnostics will determine what your issues are.

What, if any, type of exhaust recovery system do I need in my station?

Nothing has changed in regard to exhaust extraction equipment in the stations. While particulate matter (soot) is greatly diminished, all other pollutants remain (Benzene, carbon monoxide, carbon dioxide, and other noxious components). While the newer EPA compliant motors emit fewer pollutants, they still exist and must be removed from the structure.

Have A Question About An Issue On Your Truck? “Ask Ernie” The Expert - Call: 866.761.1292 ext. 106 or e-mail: [email protected]

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Issue 33.4 | Spring 2019

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