Emergency Vehicle Emissions System FAMA

Emergency Vehicle Emissions System Fama-Free PDF

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Contents ,Introduction 3 ,Fire Apparatus Emissions Regulations History 3 . 2002 3 , 2004 4 , 2007 4 , 2010 6 , DPF Emissions Problems Unique to Fire Apparatus 6 . Manual Regeneration Process 6 , Regeneration Guidelines 7 . Apparatus without Split Shaft Driven Pumps 9 , Navistar and Mid Range Cummins Engines 10 . Caterpillar Engine ARD 10 ,EPA Regulation Changes Related to DPFs 10 .
SCR Emissions Problems Unique to Fire Apparatus 11 . EPA Regulation Changes Related to SCR 12 ,General Service Suggestions 13 . Appendix A Abbreviations 14 ,Appendix B Training Checklist 15 . Appendix C Manufacturer Contacts 17 ,Appendix D Engine Reference Documents 18 . Caterpillar 18 , Cummins 19 , Detroit Diesel 20 , Navistar Maxxforce 21 . FAMA DPF and SCR Guide 130102 docx 2 1 3 2013, IInnttrroodduuccttiioonn.
This guide is intended to help fire service personnel understand the emissions. systems on fire apparatus and to provide specific guidance on how to address. emissions related concerns The issues addressed will cover CUSTOM. CHASSIS apparatus equipped with either Diesel Particulate Filters DPF or. Selective Catalytic Reduction SCR aftertreatment devices . FFiirree A, Appppaarraattuuss E, Em Reegguullaattiioonnss H. miissssiioonnss R Hiissttoorryy, Internal combustion engines have been getting cleaner for many years This. section provides a summary of the major changes that diesel engines have. undergone over the past ten years ,22000022, In response to the Clean Air Act the EPA mandated improvements in diesel. engine emissions beginning in 1990 The emissions limits were tightened in. 1994 1998 2004 and 2007 with the final goal being reached in 2010 Some. engine manufacturers implemented the 2004 standards two years early in 2002 . while Caterpillar implemented as originally scheduled in 2004 . Exhaust Gas Recirculation EGR , Fire apparatus engine manufacturers other than Caterpillar introduced. cooled Exhaust Gas Recirculation EGR beginning in 2002 EGR. reduces NOx a major contributor to air pollution by lowering the. combustion temperature inside the cylinder The components that come. with EGR include a more robust turbocharger an exhaust gas cooler and. a system that controls the amount of exhaust that is redirected through the. cooler and into the engine , When EGR is added to an engine it increases the total amount of heat.
going into the coolant This extra heat has to be removed by the radiator . FAMA approached the EPA and was able to get some relief for fire. apparatus so that radiators did not have to grow quite as much as they. otherwise would have The EPA allowed the engine manufacturers to use. special engine control software features to limit the amount of exhaust gas. recirculation when the fire apparatus was in extremely hot environments. and or under very heavy load Such engine control features are termed. Auxiliary Emission Control Devices AECDs Both Detroit Diesel and. Cummins engines incorporated AECD strategies to some extent . FAMA DPF and SCR Guide 130102 docx 3 1 3 2013, 22000044. Caterpillar ACERT , Caterpillar did not adopt EGR in 2004 but introduced a strategy they. termed Advanced Combustion Emissions Reduction Technology. ACERT They added a second turbocharger and employed. electronically controlled fuel injection to meet the emissions criteria The. higher turbocharger pressures increased the heat of the charge air . requiring larger radiators and charge air coolers just as EGR did . 22000077, The 2007 regulations tightened the criteria for NOx emissions and instituted a. 90 reduction in particulate matter or soot , More EGR . To meet the more stringent NOx criteria Detroit Diesel Cummins and. most other U S on road engine manufacturers increased their reliance on. EGR This strategy also increased the amount of heat going into the. cooling system and required apparatus manufacturers to increase the size. of their radiators and charge air coolers To gain a comfortable margin . many chassis cabs increased in width from 96 to 102 inches allowing. them to maintain driver and officer space while providing room for a larger. radiator , Diesel Particulate Filters , To meet the particulate matter regulation the only method available was.
to add a Diesel Particulate Filter DPF The most common DPFs uses. what is call a wall flow substrate typically made of porous ceramic media. that capture exhaust gas and remove PM or soot particles A typical filter. consists of an array of small channels for exhaust gas to flow Adjacent. channels are plugged at opposite ends forcing the exhaust gas to flow. through the porous wall capturing the soot particles on the surface and. inside pores of the media As soot accumulates in the filter a regeneration. event will provide sufficient heat to oxidize the soot . DPF Regeneration , The heat required to burn off the soot in the DPF can be generated. naturally when the engine is under a significant load For over the road. truck applications the engine will oftentimes be sufficiently loaded as it is. driving down the road , For fire apparatus that only take short runs and idle for hours at a time the. engine may never create enough exhaust heat for a long enough time to. complete the soot oxidation For this reason engine manufacturers need. a method of adding heat to the exhaust All engine OEMs other than. FAMA DPF and SCR Guide 130102 docx 4 1 3 2013, Caterpillar chose to do this by adding a Diesel Oxidation Catalyst DOC . ahead of the DPF , The DOC oxidizes hydrocarbons the main constituent of diesel fuel and. in the process produces heat When the emissions system senses that. the DPF is sufficiently full of soot a charge of fuel is introduced into the. exhaust stream As it passes through the DOC the fuel is oxidized and. the exhaust is heated to a temperature that will burn off the soot in the. DPF This process is termed active regeneration , Active regeneration can either take place automatically under normal.
engine operation or it can be initiated manually at the direction of the. operator , DPF Ash Cleaning , Soot mostly carbon can be burned off in the DPF but there are also. particles that cannot be burned and remain trapped in the filter This. remaining ash must eventually be mechanically removed from the filter by. removing it and having it professionally cleaned by an authorized service. center This cleaning should not be required for several hundred. thousand miles of service so most fire apparatus will likely never need the. DPF cleaned over the life of the vehicle , Caterpillar Clean Gas Recirculation . To meet the 2007 particulate regulations Caterpillar added a DPF to their. emissions system To meet the NOx regulations they took a slightly. different approach calling it Clean Gas Recirculation CGR instead of. EGR , While CGR has the advantage of introducing cleaner exhaust back into. the cylinders it requires some additional accommodations Traditional. EGR systems use the engine coolant to remove heat from the exhaust . CGR draws the exhaust gas from downstream of the DPF after the. particulates have been removed from the exhaust While this gas has very. little soot remaining it does include moisture that can condense in the. charge air cooler where trace amounts of sulfur can create an acidic mix . For this reason 2007 emissions Caterpillar engines use stainless steel. charge air coolers that resist corrosion , Another unique feature of the Caterpillar engine is the method used for. active regeneration of the DPF The CAT DPF does not include a DOC . Instead the Caterpillar system uses a fuel injector and igniter located in. the exhaust just downstream of the turbocharger outlet This method. directly heats up the exhaust gas It is a very tricky process as the. exhaust is depleted of oxygen and flowing very rapidly The igniter must. keep the flame alive in this very chaotic environment For this reason it is. FAMA DPF and SCR Guide 130102 docx 5 1 3 2013, critical that the injector and igniter be maintained in peak condition for the.
regeneration process to work effectively ,22001100. The EPA s latest move to clean up diesel emissions came in 2010 Particulate. matter limits were unchanged but the NOx limit dropped another six fold from the. 2007 limits Caterpillar decided to drop out of the on road engine market leaving. only Cummins Detroit Diesel and Navistar as viable options for custom fire. apparatus , EGR DPF SCR , Detroit Diesel and Cummins both chose to adopt Selective Catalytic. Reduction SCR as their means to meet the new NOx limits SCR. systems add a catalyst canister in conjunction with a liquid called Diesel. Exhaust Fluid DEF also known as urea When injected into the exhaust. stream the DEF is transformed into ammonia which works with the SCR. catalyst to convert the NOx into nitrogen and water This process is very. effective at eliminating NOx from the exhaust An SCR equipped engine. can therefore be tuned to improve fuel economy and reduce soot while still. meeting stringent emissions criteria , Maxxforce Extreme EGR DPF . The only U S engine OEM that did not initially embrace SCR was. Navistar Their Maxxforce engines increased the use of EGR increased. injection pressure and otherwise modified the combustion chamber to. drive down NOx emissions This did not get them all the way so they used. emissions credits to make up the compliance deficit . Navistar has abandoned this strategy and beginning in 2013 will be using. Cummins SCR technology on their diesel engines ,D. DPPFF E, Emmiissssiioonnss P, Prroobblleem Unniiqquuee ttoo FFiirree A.
mss U Appppaarraattuuss,M,Maannuuaall R, Reeggeenneerraattiioonn P. Prroocceessss, Most over the road trucks will often times burn off the soot captured in the DPF. through the heat produced naturally from high engine loads over hours of regular. operation Unfortunately many fire apparatus make frequent short runs and may. not get the exhaust hot enough to keep the DPF burning off the soot efficiently . Build up of soot in the DPF is indicated by a series of warning lights on the dash . The typical sequence begins with the illumination of the DPF lamp When the. DPF lamp comes on it means that the filter has loaded up with soot to a point. that an intervention by the operator is necessary The apparatus needs to be. operated at higher load by driving or pumping or a manual regeneration needs. to be performed If action is not taken and soot continues to build up the DPF. lamp may begin to flash followed by a check engine lamp and eventually a stop . FAMA DPF and SCR Guide 130102 docx 6 1 3 2013, engine lamp Consult your operator manual for the exact sequence for your. particular apparatus and engine , Frequent need for regeneration has by far been the most common emissions. related complaint with fire apparatus While many departments report that they. have had little or no difficulty there was a sufficient level of frustration in the. industry to get the attention of leaders in the EPA EPA scientists interviewed fire. chiefs and made on site visits to assess the situation Based on their. investigation the EPA proposed and then instituted regulatory changes meant to. help reduce any negative consequences of emissions system operation . R,Reeggeenneerraattiioonn G, Guuiiddeelliinneess, Given the technology required to meet the EPA regulation and the typical fire.
apparatus duty cycle it is unlikely that departments operating 2007 and later. emissions systems will be able to entirely avoid the need to perform manual. regenerations FAMA has the following recommendations to minimize both the. number of manual regenerations and the impact on fire service operations . Keep the Apparatus In Service during Manual Regen . A common misconception is that the apparatus must be taken out of. service during a parked regeneration This is not the case If the DPF. lamp is illuminated park the apparatus outside on a level surface with the. parking brake applied and the transmission in neutral Engage the manual. regeneration switch The engine will begin the active regeneration. process once the exhaust temperature is hot enough and will continue. until the soot in the DPF has been burned off Expect this process to take. between 20 and 40 minutes , If a call comes in before the regeneration process is complete simply. operate the apparatus as you would in any normal call The regeneration. process will be interrupted by tapping the service brakes or by releasing. the parking brake If the DPF lamp is still illuminated when you return. from the call park the apparatus and engage the manual regen switch as. before The process will begin again from where it left off If the DPF. lamp has gone out it is probably because the duty cycle involved in the. call continued to regenerate the DPF and the remaining soot was burned. off naturally, Limit the Use of the Regen Inhibit Switch . Most apparatus are equipped with a regeneration inhibit switch The. regen inhibit switch is meant to be used sparingly only if the apparatus is. operating near a hazardous source of combusion Inhibiting the automatic. Emergency Vehicle Emissions System Guidance Document Custom Fire Apparatus Exhaust Gas Recirculation EGR Fire apparatus engine manufacturers other than Caterpillar introduced cooled Exhaust Gas Recirculation EGR beginning in 2002 EGR reduces NOx a major contributor to air pollution by lowering the combustion temperature inside the cylinder The components that come with EGR

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