Aftertreatment Technologies

Clean Emissions Module (CEM)
The CEM protects interior components, minimizes the aftertreatment footprint and simplifies maintenance.

 Diesel Oxidation Catalyst (DOC) The DOC uses a chemical process to reduce hydrocarbons and carbon monoxide in the exhaust stream. No maintenance is required because the DOC is a “flow-through” device.

 Diesel Particulate Filter (DPF)
A DPF traps particulate matter that’s carried in the exhaust stream, preventing it from being released into the atmosphere. Inside the DPF, particulate matter, sometimes referred to as “soot,” is trapped until it is oxidized during regeneration.

 Selective Catalytic Reduction (SCR)
         The SCR system consists of a SCR catalyst, AMOX and the Pump Electronics Tank Unit (PETU). This system uses a small amount of Diesel Exhaust Fluid (DEF) to convert NOx emissions in the exhaust into nitrogen and water. No major redesign was necessary to accommodate this system into Cat machines as the space claim required did not change from our Tier 4 Interim design.

Ammonia Oxidation Catalyst (AMOX)
         In order to ensure sufficient NOx reduction, a small amount of excess Diesel Exhaust Fluid (DEF) is injected into the exhaust stream. This excess DEF may pass through the Selective Catalytic Reduction (SCR) catalyst as ammonia. To prevent excess ammonia from entering the atmosphere, the exhaust gas flows through an Ammonia Oxidation Catalyst (AMOX) where the ammonia reacts with oxygen in the presence of this catalyst to form nitrogen and water.

Pump Electronics Tank Unit

         The PETU is responsible for storing, controlling and supplying the appropriate quantity of Diesel Exhaust Fluid from the DEF tank to the DEF injector. The Diesel Exhaust fluid is used by the SCR system to reduce NOx emissions in the exhaust.

         DEF is a solution of urea dissolved in deionized water to produce a concentration that is about 1/3 urea and 2/3 water. DEF used in Cat engine systems must meet the requirements outlined in ISO 22241-1.