(a) The exhaust pipe, after-treatment system, and tailpipe shall be:

1. (1) Outside the bus body compartment; and
2. (2) Attached to the chassis so any other chassis component is not damaged.

(c)

1. (1) The tailpipe may be flush with, or shall not extend more than two inches (2”) beyond, the perimeter of the body for side-exit pipe or the bumper for rear-exit pipe.
2. (2) The exhaust system shall be designed such that exhaust gas will not be trapped under the body of the bus.

(d)

1. (1) The tailpipe shall exit to the left or right of the emergency exit door in the rear of the vehicle or to the left side of the bus in front of or behind the rear drive axle, or the tailpipe may extend through the bumper.
2. (2) The tailpipe exit location on all Types A-1 or B-1 buses may be in accordance to the manufacturer’s standards.

3. (3) The tailpipe shall not exit beneath any:

   1. (A) Fuel filler location;
   2. (B) Emergency door; or
   3. (C) Lift door.

(f)

1. (1) The design of the after treatment systems shall not allow active (nonmanual) regeneration of the particulate filter during the loading and unloading of passengers.
2. (2) Manual regeneration systems will be designed such that unintentional operation will not occur.

(g) For after treatment systems that require diesel exhaust fluid (DEF) to meet federally mandated emissions:

1. (1)

   1. (A) The composition of diesel exhaust fluid (DEF) must comply with international standard ISO 22241-1.
   2. (B) Refer to engine manufacturer for any additional DEF requirements.
2. (2) The DEF supply tank shall be sized to meet a minimum ratio of three (3) diesel fills to one (1) DEF fill.