4.3.4.4 Supply unit (SU)
1 HDSC connector, DU
2 HDSC connector, DCM
3 Outlet to DU (pressure line)
4 Inlet from PFM
5 Filters
6 Electrical heating element
7 Pressure relief valve
The SU comprises a diaphragm pump, an RA prefilter, a pressure limiting valve to protect the system, and an
integrated electronic control system. Two supply units are installed for each SCR system.
Design criteria
Design criteria
Value
Material
Aluminum (pump block)
Polyamide (filter housing)
Technical data
Operating pressure: 10 bar abs.
RA dosing volume: Max. 11 kg/h
Suction head: Max. 0.1 bar / 1 m
Rated supply voltage
24 VDC
Protection class
IP69 K
Ambient temperature
-40 °C to 60 °C (with electrical heating)
The SU must be mounted horizontally ±10° because of the filter.
Function
The SUs and DUs are the main components for pressurization and dosing, and provide a defined reducing
agent spray and quantity set by the Engine Control Unit.
The integrated electronic control assembly controls the 10 bar system pressure via pump speed and ac-
tuates the metering valve of the DU.
84 | RA Dosing System | MS15065/01E 2019-01
TIM-ID: 0000072392 - 001
