Understanding the Differences Between Stage 3 and Stage 4 Generators

Jun 19,2024

Generators play a vital role in providing backup power in emergency situations or in remote areas where electricity is not readily available. When it comes to generators, understanding the differences between Stage 3 and Stage 4 models is critical to making an informed decision as to which model is right for your specific needs.

From emissions standards to fuel efficiency, each stage of generator technology offers unique benefits and considerations. In this blog, we’ll explore the key differences between Stage 3 and Stage 4 generators to help you make the best choice for your power needs.

What is a Tier 4 Generator?

A Tier 4 generator is a type of generator that meets specific emission standards set by the Environmental Protection Agency (EPA) in the United States.

These generators are designed to reduce harmful emissions such as nitrogen oxides (NOx) and particulate matter, making them more environmentally friendly compared to older generator models.

Tier 4 generators are commonly used in construction sites, industrial facilities, and other applications where reliable power is needed.

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How Tier 4 Generators Work?

Tier 4 generators work by utilizing advanced emission control technology to reduce harmful pollutants in the exhaust gases produced during operation. These generators are designed to meet strict environmental regulations set by the U.S. Environmental Protection Agency (EPA) and other regulatory bodies.

Tier 4 generators typically use a combination of diesel particulate filters (DPF) and selective catalytic reduction (SCR) systems to reduce emissions of nitrogen oxides (NOx) and particulate matter.

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The DPF traps and removes soot particles from the exhaust gas, while the SCR system uses a reducing agent (such as urea) to convert NOx into harmless nitrogen and water vapor.

The implementation of these technologies in Tier 4 generators helps to minimize air pollution and improve air quality, making them more environmentally friendly compared to older-generation diesel generators.

In addition, Tier 4 generators are more fuel-efficient and can provide reliable power for a wide range of applications, including construction sites, emergency backup power, and remote off-grid locations.

Why Choose Tier 4 Generators?

Selecting a Tier 4 diesel generator that complies with EPA diesel engine regulations is paramount for a multitude of contemporary applications.

For enterprises such as construction firms, manufacturing businesses, hospitals, or data centers, ensuring access to a dependable power source during outages is critical to prevent significant financial losses.

Here are some reasons why a Tier 4 diesel generator is the best choice for your business:

Environmental Stability

Tier 4 generators represent a significant advancement in environmental sustainability, boasting a reduction of approximately 90% in particulate matter, nitrogen oxide, and sulfur emissions compared to Tier 3 generators.

Advanced Technology

Engineered with cutting-edge technology, Tier 4 generators are equipped with advanced features such as diesel particulate filters to enhance air quality. Furthermore, select models offer the convenience of remote control through a mobile application.

Reliable Backup

Tier 4 generators provide a reliable power supply for businesses and large residential properties during outages, while minimizing the release of hazardous emissions.


Tier 4 generators, in conjunction with diesel engines, enhance system efficiency and ensure reliable backup power during outages.

Key Differences Between Tier 3 and Tier 4 Generators

  1. Emissions Standards

Tier 3 generators follow less strict emissions standards compared to Tier 4 generators. Tier 4 generators are designed to meet stringent emissions regulations set by the Environmental Protection Agency (EPA).

  1. Emission Control Technology

Tier 3 generators typically use basic emission control technologies such as exhaust gas recirculation (EGR) and diesel particulate filters (DPF), while Tier 4 generators use advanced emission control technologies such as selective catalytic reduction (SCR) and diesel oxidation catalysts (DOC) to achieve lower emissions levels.

  1. Fuel Efficiency

Tier 4 generators are more fuel-efficient than Tier 3 generators, as they are designed to optimize fuel combustion and reduce emissions.

  1. Cost

Tier 4 generators tend to be more expensive than Tier 3 generators due to the advanced technology and components required to meet stricter emissions standards.

  1. Maintenance

Tier 4 generators require more frequent maintenance compared to Tier 3 generators, as the advanced emission control systems need to be regularly monitored and serviced to ensure optimal performance.

  1. Availability

Tier 3 generators may still be available for purchase in some regions where Tier 4 emissions regulations have not been mandated. Tier 4 generators are becoming more prevalent as emissions standards continue to tighten globally.

Tier 4 generators offer better environmental performance, fuel efficiency, and long-term cost savings compared to Tier 3 generators, making them a preferred choice for organizations looking to reduce emissions and operating costs.

Which Tier generator is right for you?

In general, Tier 3 and Tier 2 generators are acceptable for use as emergency power sources. These generator tiers have considerably reduced emissions relative to earlier models and, given that standby units typically operate for limited durations, their effect on air quality is minimal.

However, it’s imperative to note that both primary and portable generators must comply with Tier 4 standards.

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Although utilizing a Tier 4 generator may not be essential for every application, it invariably offers substantial benefits. Furthermore, certain regulatory authorities mandate the use of Tier 4 generators in particular regions and industries.

If there is uncertainty regarding the most suitable tier for your requirements, it is advisable to seek guidance from an expert. In cases of doubt, opting for a Tier 4 model could be a prudent decision to ensure regulatory compliance and reduce emissions from your operations.


While both Tier 3 and Tier 4 generators offer reliable and efficient performance, understanding the differences in emissions standards and environmental impact can help you make an informed decision.

By carefully evaluating your power needs and considering the specific regulations in your area, you can choose the generator that best suits your needs.

The Powerlink team possesses extensive expertise in assisting you with the selection of the most suitable generator for your job site or facility. We offer and maintain a comprehensive range of power generation solutions, equipped with advanced Tier 4 diesel engines.

Please get in touch with our team for detailed information regarding our generators and their adherence to EPA regulations.

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