• Exhaust system requirements for a semiderelict tractor trailers in a row image by Bo Widerberg from Fotolia.com
  
  The Federal Motor Carrier Safety Administration, a division of the Department of Transportation (DOT), issues the requirements for a semi's exhaust system. The requirements are listed under federal regulation 393.83 and consist of nine specific requirements that regulate the safe operation of the system. As of 2010 there are no requirements to mediate the exhaust fumes from a semi, but that will change in 2014.
  
  

Location of Exhaust System and Discharge

• No part of the exhaust system can be located where the fumes could cause burning, charring, damage to the fuel supply, the wiring or any combustible section of the vehicle. The system cannot discharge exhaust below the fuel tank or fuel tank filler pipe, forward of the semi's cab or below the cab or sleeper compartment.
  
  

Installation Manner of the Exhaust System

• The exhaust system must be securely fastened to the vehicle but may be installed on a hanger that allows for the movement of the system during the operation of the vehicle and that allows for the natural expansion and contraction of the exhaust fumes.
  
  

Prohibited Repair Techniques

• The exhaust system cannot be repaired with temporary patches or wraps; permanent repair measures are required.
  
  

Upcoming Changes in Specifications

• In October, 2010, the Environmental Protection Agency (EPA) and the DOT announced the first-ever rule designed to regulate emissions from the exhaust system of semis. The changes will take effect between 2014 and 2018. See the Resources section for a link the further information.