1 urea tank must be the material that is resistant to urea corrosion, medium density polyethylene is best. 2 OBD requirements for the detection of urea consumption, so the design of the urea tank to ensure that the height and volume of the box is linear relationship. 3 equipment should ensure that the urea tank and urea pipe cleaning (in connection with the pipeline can not be pulled out of the dust cover).   4; urea tank to vent. 5 must be on the box warning "only allowed to add urea" 6 urea fluid outlet should be with 70 micron filter