INERGY as a recognized expert in its field monitors and participates to the setting up of new regulations.
Introduction to evaporative emissions
When the temperature of a fuel system increases, the fuel vapors expand. The evaporative emissions or resting losses of a vehicle can be as important as the pollutants from the vehicle exhaust tailpipe. Evaporative emissions regulations assure that these vapors trapped in a carbon canister. Evaporative emissions also force fuel system materials and designs that limit leak and permeation emissions.
All global evaporative emissions regulations follow the same basic certification test flow.
1- The carbon vapor canister is prepared and loaded
2- Fresh fuel is added to the fuel system
3- The vehicle is preconditioned through a drive cycle
5- Running loss test
6- Hot soak test
7- Diurnal emission test
SHED temperature cycles (diurnal temperature profiles)
Regulations apply different temperature cycles. Temperature drives evaporative emissions: high temperatures drive emissions; large changes in temperatures drive emissions. California CARB temperature profile has both the highest temperatures and the biggest temperatures swings. CARB cycles drive higher evaporative emissions than either EPA or Euro cycles. Euro cycle emissions are 75% of CARB cycle emissions.
United States evaporative emissions
US regulations (EPA Stage II enhanced/CARB LEVII) limit evaporative emissions to 0.5g/day over a 3 day diurnal temperature profile. US Environmental Protection Agency (EPA) regulates federal vehicle emissions standards. Normally, state regulations can not exceed federal regulations. However, California Air Resources Board (CARB) has an exception or waiver allowing more critical vehicle emissions standards. Other US states can adopt the California regulations under the California waiver provided that State does not meet any one of the National Ambient Air Quality Standards (NAAQS). Almost 50% of US population is in an ARB state. Links:
Official summary and text of Tier II (EPA) evaporative standards (external link)
EPA regulations regarding vehicle emissions (external link), US Federal CFR, title 40, part 86
Official summary and text of LEV II (CARB) evaporative standards (external link)
US regulations: PZEV
PZEV regulations are part of Zero Emissions Vehicle in California to promote fuel cell and electric vehicles. PZEV compliance mechanism was adopted in 1998 (LEV II) to encourage the development of emerging near-zero emission technologies and provide option to pure ZEVs. PZEV vehicles are 'traditional' vehicles with internal combustion engines and fuel systems, but they have very low tailpipe and evaporative emissions. Evaporative emissions for PZEV vehicles are limited to 0.350g/day plus the fuel related emissions must be below 0.054g/day (PZEV rig test). The credit structure was modified in January 2011 (added AT-PZEV category).
US regulations: LEV III evaporative emissions outlook
CARB will propose LEV III regulations in 2011 for implementation beginning in 2014. LEV III is foreseen to reduce the emissions of the 'average' vehicle to the level of current SULEV/PZEV vehicles. Whole vehicle evaporative emissions will likely be reduced from 500mg/day (LEV II/Tier 2 standard) to 300mg/day. Certification of 'zero' fuel emissions (PZEV rig test of 0.054g/day) will not be required. However, it is likely that bleed emissions of <0.020g/day will need to be demonstrated. Certification fuel for LEV III will be a 10% Ethanol/Reformulated Gasoline blend with 7RVP.
LEV III development documents (external link)
Japanese emissions regulations
Japanese emission standards for engines and vehicles are jointly developed, under the authority of the Air Pollution Control Law, by two government ministries: the Ministry of the Environment (MOE) and the Ministry of Land, Infrastructure and Transport (MLIT). Evaporative emissions standards in Japan are very similar to Euro 4 standards.
Japanese emissions standards (external link)