DEF System Design for Caterpillar Generators
Earthsafe has developed a Flow Control Unit specifically for Caterpillar SCR Emissions System. The CAT System has a DEF Urea Dosing Unit with buffer tank that requires a 5 – 10 PSI inlet feed of DEF with overpressure protection at 10 PSI. This can be a tough requirement if the DEF storage tank is remote or there are multiple generators being fed DEF from a single bulk tank.
The low pressure can be achieved by a flow scheme shown above. The system is setup to circulate DEF continuously or at least whenever the generators are running. The circulation lop operates at a 10-25 PSI pressure range to assure adequate flow to the point of use.
The DEF Flow Control Unit is operated by sensing a pressure drop in the feed, meaning that the CAT buffer tank inlet valve is open and requesting refill. Then the Flow Control Solenoid Valve is energized to open and allows flow through the pressure reducing valve to the buffer tank inlet.
When the buffer tank is satisfied, the pressure rise will close the inlet solenoid valve, isolating the buffer tank inlet from the higher pressure of the circulation loop.
For More Information here is our new Design Guide: