SCR Part- Metering Pump- 4 working status
Four Working Status of Metering Pump
1. Stop Status
Engine does not work, metering pump is at shutdown, air solenoid valve is closed, urea pump is stationary and urea can not enter the metering pump.
2.Empty Status
When the engine is running, the feeding pump will enter empty state.Urea liquid circulates through pump and flues back to urea tank to empty the air of the system. If emptying air successes, the motor of feeding pump will work in full for 30 seconds and the air solenoid valve will start to work after this state.
Faults easy to happen at this stage:
No compressed air, urea pump will work all the time; open air solenoid valve once 30 seconds, alarm after 20 circulations; no urea liquid, alarm after 20 circulations; return tube is blocked, alarm during the first circulation.
3.Jetting Status
At the end of the stage, air solenoid valve opens and the motor of urea pump stops. The pump is ready to jet. YCDCU will control according to nitrogen oxides produced by engine and exhaust temperature during the jetting phrase.
Urea pump will not add urea liquid unless two exhaust temperature sensors reach around 200 degree, but will inject air continuously while the engine is running to avoid the spray nozzle being blocked.
>>>Compressed air has two functions: To convey, mix and atomize urea liquid; To avoid the spray nozzle being blocked;
>>>Faults easy to happen at this stage: The spray nozzle may be blocked by urea crystallization and carbon deposition. Please disassemble and clean.
4. Purging Status of Urea Pump
When the key switch is turned to the off position, the system enters the purging phase. Compressed air flows through the nozzle and pump.
Air drains any residual liquid from the system that might otherwise block the pump valve or injector nozzle.
This phase will last for 30 seconds and then the system will shut down.
Every time the key switch closes the circulation, urea pump will empty air.
To ensure that the pump can continue to purge after the key switch turns off, the pump power must be connected with long power supply.