Tier 3 and Tier 4 Final are emissions standards set by the U.S. Environmental Protection Agency (EPA) for off-road diesel engines. These standards are designed to limit the number of pollutants emitted by diesel engines to reduce their impact on air quality and public health.
Tier 3 Standby Diesel Engines:
EPA certified for emergency standby use
Emission Standards: Tier 3 standards were introduced in 2006, focusing on reducing nitrogen oxides (NOx) and particulate matter (PM) emissions.
Applicability: Tier 3 standards primarily apply to engines used in off-road applications, including standby or emergency generators, construction equipment, and agricultural machinery.
Technology: Tier 3 compliant engines typically use technologies such as advanced combustion controls and optimized fuel injection to meet the emission standards.
NOx and PM Limits: Tier 3 sets limits on both NOx and PM emissions, but the standards are not as strict as those in later tiers.
Tier 4 Final Diesel Engines:
EPA certified for prime power and mobile applications
Emission Standards: Tier 4 Final standards are more stringent and were phased in from 2014 to 2015. These standards focus on further reducing NOx and PM emissions.
Applicability: Like Tier 3, Tier 4 Final standards apply to off-road diesel engines used in various applications, including construction, agriculture, and industrial equipment.
Technology: Tier 4 Final engines employ advanced emission control technologies, including selective catalytic reduction (SCR), diesel particulate filters (DPF), and advanced exhaust gas recirculation (EGR) systems. These technologies work together to achieve lower emission levels.
NOx and PM Limits: Tier 4 Final has more stringent limits on both NOx and PM emissions compared to Tier 3. The use of advanced aftertreatment systems is a common feature in engines designed to meet Tier 4 Final standards.
In summary, the main differences between Tier 3 standby diesel engines and Tier 4 Final diesel engines lie in the stringency of the emission standards and the technologies employed to meet those standards. Tier 4 Final engines use more advanced and complex emission control technologies to achieve significantly lower levels of pollutants compared to Tier 3 engines.
Emissions standards for diesel generators can vary by state and are subject to change over time. The regulations are typically set by state environmental agencies or air quality management districts.
