SCR Retrofit Aftertreatment Caterpillar

Normal periods of inactivity will not require special attention to the SCR system. Extended periods of inactivity or product storage will require preventative maintenance preparations up to, and including:

• Purging DEF and water from the emissions reduction system.

• Shutting off the system prior to storage.

• Cover or plug all inlet and outlet fittings.

• Cover any exposed electrical connection fittings.

• Protect the dosing cabinet from inclement weather.

Diesel Exhaust Fluid (DEF) Circulation System

• Disconnect electrical service to the DEF supply/circulation system if applicable.

• Close all ball or gate valves within the circulation loop.

• Shut off all ball valves to the dosing cabinets.

• Close off ball or gate valves coming from the DEF (Urea) holding tank.

Dosing Cabinets

Follow the steps in the System Operation Test and Adjust Service Manual to ensure that SCR system is purged of all Diesel Exhaust Fluid (DEF). DEF will crystallize and potentially damage the components in the SCR system, if the DEF is left in the system for an extended time.

If the catalyst or DEF nozzle remains in the exhaust flow, the dosing cabinet must remain operational and compressed air must continue to be supplied. The Dosing cabinet ECM is monitoring catalyst health even when the system is deactivated.

Removal of DOC or DPF

• Remove all fasteners from the inspection hatch.

• Loosen V bands and remove the DOC/DPF.

• Remove all gasket material.

• Reinstall inspection hatch.

• Store DPF or DOC in a clean and dry location.

Removal of SCR Bricks

• Remove all fasteners from the inspection hatch.

• Remove SCR bricks from the reactor.

• Remove all insulation and foreign material before exiting the reactor.

• Discard all insulation. Insulation cannot be reused.

• Reinstall the inspection hatch.

• Store the SCR in a clean and dry location.

DOC/DPF/SCR Storage

Catalysts removed from the reactor housing for storage must be stored in an indoor environment out of direct sunlight and moisture. The temperature range for storage is −30° C (−22° F) to 80° C (176° F). The humidity must be maintained between 20 percent and 80 percent. Exposure to higher humidity levels will affect the catalyst coating which will affect performance.

Store the catalyst on the side with the ceramic face exposed to minimize damage to the face. Cover the face of the catalyst to avoid debris contamination.

Note: The maximum shelf life for the catalyst that will not affect the catalyst performance is 2 years.

Removal from Extended Storage (DEF Remaining Tank)

If the DEF tank was stored for a duration equal to or exceeding that listed in table 1 at the corresponding temperature, replace the DEF.

If the DEF quality is in doubt, test with a refractometer. For more detailed information about testing DEF quality, contact the local Caterpillar dealer.

Table 1

Temperature	Duration
10° C (50° F)	36 months
25° C (77° F)	18 months
30° C (86° F)	12 months
35° C (95° F)(1)	6 months

(1)	At 35° C, significant degradation can occur. Check every batch before use.

1. Drain DEF from the tank, and refill with DEF.

2. Replace the DEF filter. (if equipped)

3. Start the engine. If a fault code becomes active, turn off the engine, allow 2 minutes to purge, then restart the engine.

4. If a fault code continues to stay active, Refer to Troubleshooting.