Urea common rail

An exhaust after-treatment system, comprising:

• an exhaust passage;
• at least one exhaust treatment component located in the exhaust passage;
• a plurality of dosing modules for dosing an exhaust treatment fluid into an exhaust stream passing through the exhaust passage;
• a common rail providing the exhaust treatment fluid to each of the dosing modules, the common rail being divided into a first pair of rails that are each arranged to allow gravity-assisted drainage of the exhaust treatment fluid therefrom.

An exhaust after-treatment system, comprising:

• an exhaust passage configured to divide into a plurality of legs;
• an exhaust treatment device disposed in each of the legs;
• a plurality of dosing modules for dosing an exhaust treatment fluid into the exhaust passage, at least one of the plurality of dosing modules being associated with a corresponding leg of the exhaust passage;
• a common rail configured to provide the exhaust treatment fluid to each of the dosing modules;
• a return rail configured to receive unused exhaust treatment fluid from each of the dosing modules;
• and
• a plurality of valves configured to control entry of exhaust from the exhaust passage into each of the plurality of legs,
• wherein at least one of the common rail and the return rail is configured to include a portion positioned at a height greater than another portion thereof such that any unused exhaust treatment fluid will drain therefrom.