Exhaust Aftertreatment Tips
The purpose of heavy equipment exhaust aftertreatment systems is to reduce the amount of harmful emissions and pollutants that machines release into the air. There are various different types of aftertreatment systems that modern equipment may have, but they all work towards the same goal of cleaning the diesel exhaust and ensuring your machine complies with EPA regulations.
Proper maintenance of the exhaust aftertreatment system is crucial to avoiding damage to the system itself and your engine, as well as to ensuring the overall health and performance of the equipment. Follow our best practices for maintaining your aftertreatment system.
Exhaust aftertreatment system variations
- Diesel Particulate Filter (DPF), which includes a Diesel Oxidation Catalyst (DOC)
- DOC plus Selective Catalyst Reduction (SCR)
- DOC, DPF and SCR
A DPF filter traps the particulate matter (PM), also called soot, that is normally responsible for the black color of diesel exhaust. The DPF traps the particulates until it becomes full, at which point a regen is required to oxidize the PM and decrease the soot load. However, the regen process will leave ash behind, which must be removed by having the DPF professionally cleaned. We recommend having your DPF cleaned once every 3,000 hours to maintain optimal performance.
Most manufacturers are required to utilize SCR and diesel exhaust fluid (DEF) systems on engines over 75 hp. These systems inject DEF into a special catalyst that converts nitrogen oxide (NOx) into nitrogen, water, and small amounts of carbon dioxide. When it comes to SCR systems, it's important to pay close attention to your DEF levels. Most new machines have easy to read gauges to alert operators when the levels are low. To maintain the long term health of your SCR system, check your owner's manual to see how often to change the DEF filter, normally about every 3,000 hours.
How to perform a regen
A regen or regeneration cycle cleans your diesel particulate filter (DPF) by essentially "cooking" it and burning away most of the particulates with temperatures exceeding 1,000 degrees. Regen procedures can differ between manufacturers but most will alert the operator when a regen is occurring or when the operator needs to perform a regen.
Some new machines have the ability to run an auto regen while the machine is still in operation. However, in certain situations, a stationary regen is required. If the regen cannot occur while the machine is working, then the operator should do the following:
- Park in a safe area
- Idle the machine all the way down
- Lift the safety bar
- Ensure engine coolant temperature is at or above 65 degrees C
- Push/hold the regen enable switch until the engine idles up
Common aftertreatment maintenance mistakes to avoid
There are a number of mistakes that owners and operators often make with regards to their machines' exhaust aftertreatment systems. Avoid these practices to ensure your system works properly.
- Ignoring regeneration alerts
- Using low quality DEF (can damage DEF injection system)
- Accidentally pouring diesel fuel into the DEF system (damages the quality and pressure sensors in the DEF injection system, in addition to damaging the SCR. A mistake like this can cost upwards of $10,000)
- Removing the DPF and blowing it out with an air hose (this is illegal as it blows all the pollutants caught by the DPF into the atmosphere. The DPF needs to be professionally cleaned)