Loading... Please wait...

Introduction to EPA: Environmental Standards for Generators

Posted by

General Power EPA compliant diesel generators

The Environmental Protection Agency 1 or EPA is an agency that strives to protect human health and the environment through clean air, land and water initiatives. These initiatives include standards that govern generator emissions standards in the interest of conservation and to reduce risks associated with air pollution.

What is an EPA-compliant generator?

A generator is considered EPA-compliant if it meets the national standards and regulations2 set forth by the Environmental Protection Agency for nonroad compression-ignition (NRCI) engines. These standards are confirmed by certain test procedures, proper labeling and warranty obligations.

What is the TPEM program?

The Transition Program for Equipment Manufacturers3, or flexibility program, is a program for equipment manufacturers that offers a temporary exemption from installing engines with the latest tier regulations4.

The EPA uses multiple tiers of emission standards, so this exemption provides manufacturers with a reasonable timeframe to make the necessary adjustments to their equipment to accommodate new engine design changes.

This program allows diesel equipment manufacturers to delay installing Tier 4-compliant engines with advanced emission control technologies in their products. Participants must comply with certain production limitations and paperwork requirements. Get up-to-date regulations and information on the EPA’s website.

What requirements apply under the TPEM program for equipment-manufacturer flexibility?

The transition program is currently only available to manufacturers of nonroad compression-ignition equipment. All equipment manufacturers of such engines must comply with certain production limitations and requirements for notification, recordkeeping, and annual reporting in order to work under the program for equipment-manufacturer flexibility.

Under the TPEM, original equipment manufacturers have specific limitations on the quantity of previous-tier engines that they install on a yearly basis. These limitations are grounded on a percentage of production allowance or a small volume allowance. The specific provision is chosen by the OEMs.

  • Percentage of production allowance: This provision allows, over the seven-year period, for OEMs to install non-Tier 4 interim or non-Tier 4 final engines on a total of 80 percent of their production. Meaning that an original equipment manufacturer would be able to install Tier 3 engines on 50 percent of their entire production for the first year, 20 percent of their entire production for the second year, and 10 percent of the entire production for the third year. After the limit has been met, all engines installed by OEMs must comply with Tier 4 interim or Tier 4 Final standards.
  • Small volume allowance: With this provision, OEMs with more limited offerings can surpass the cumulative percentage. However, they must limit their production to one of the following criteria:
Engine HP Limits         
A total of 700 units over the entire Tier 4 allowance period involving one engine family per power category

Engines below 175 HP / 525 units in a  single power category                                                
No more than 150 units per year in multiple engine families over the Tier 4 allowance period

Engines greater than 175 HP / 350 units in a single power category
No more than 100 units per year in multiple engine families over the Tier 4 allowance period.

Every EPA-compliant engine must have the proper equipment labeling to indicate that it meets the national standards and regulations for nonroad compression-ignition engines. EPA Flex engines must also have a permanent label to supplement the engine manufacturer's emission control information label.

How can I know if an engine is EPA Flex?

Transition Program for Equipment Manufacturers label generators

This label indicates that the engine is exempt under the Transition Program for Equipment Manufacturers. Proper, visible labelling included the following information:

  1. The label heading “EMISSION CONTROL INFORMATION.”
  2. Manufacturing name and trademark.
  3. The calendar year in which the equipment was manufactured.
  4. The following statement: THIS EQUIPMENT [or identify the type of equipment] HAS AN ENGINE THAT MEETS U.S. EPA EMISSION STANDARDS UNDER 40 CFR 1039.6255.

Do I need to recertify current units for future EPA requirements?

No, the EPA only requires equipment to comply with the laws of the year in which the engine was manufactured.

Do I need a Tier 4 or Flex certification for emergency-only applications?

Because Emergency Standby Power installations have a minor impact on the local air quality, they are exempt from having to meet the Tier 4 interim and Tier 4 final engine standards as long as their emission rates comply with Tier 2 and Tier 3 engines.

However, since 2008 generators that are below 50 HP are required to use Tier 4 interim engines. These exceptions apply as long as the units are used strictly for emergency applications. it’s extremely important to note that state and local authorities have the right to dictate stricter regulated emissions limits which do not allow for the aforementioned exemptions.

When is a generator considered an Emergency Standby unit?

Generators that will only operate in emergency occasions are considered Emergency Standby Units. These units automatically begin to supply energy upon sudden loss of power. As soon as the main electricity or utility power is back up the generator will shut down.

Because EPA regulations only allow these units to run a maximum of 200 hours of use per year, it is crucial for the operator to log all hours of operations into a non-resettable recorder fitted into the generator. New manufactured units must come with their respective permanent labels specifying that their use is only for emergencies.

When is a generator considered a Stationary Prime unit?

Generators installed in one permanent location or units that have been in the same location for at least 12 consecutive months will be considered Stationary Prime Units. These units are required to meet Tier 4 Final regulations.

When is a generator considered a Mobile Prime unit?

If a generator is mounted on a trailer, vehicle, or is moved from one location to another more than once in a 12-month period, it is considered a Mobile Prime Unit. Therefore, they must comply with TPEM Flex or Tier 4 Final standards, depending on your local authorities.

When do I need to buy a generator with a TPEM Flex or Tier 4 Final engine?

You need to buy a Tier 4 final engine if you are planning to use the generator:

  • To power machinery or utility equipment
  • For load management
  • As the primary power source when no alternative sources are available
  • For a temporary power application where it serves as the primary source of power
  • In any situation when the unit is mounted on a trailer or vehicle, or when the generator will be moved more than once in a 12-month period

All of these applications require the use of a TPEM Flex or Tier 4 Final engine. We recommend verifying the exact requirements with your local authorities.

Can I use a TPEM Flex engine for a stationary standby application?

No, it is a direct violation of the TPEM Flex exception program to use Flex engines for stationary emergency applications.

How can I know which EPA certification my engine needs for my application?

In order to determine which EPA certification is needed for your particular engine please refer to the standards of the application you will be using for your generator set.Note: Always consult your local generator distributor/dealer for the latest regulations that will apply to your particular installation.

Are there any other EPA regulations that I need to be aware of?

EPA regulations apply to all states within the United States, with no exemptions. Nonetheless, stringent regulations might be placed by state legislation (with CARB regulations in California being a great example). Therefore, any unit that is compliant with EPA regulations might still not meet local requirements.

These requirements are placed depending on the environmental factors of each individual state. For the latest information related to state environmental regulations please consult your local generator distributor.

Does General Power offer TPEM “Flex” generators?

Yes, General Power offers TPEM “Flex” generators. To browse our list of available generators, please visit our TPEM Flex Generators category page.

Does General Power offer “Tier 4 Final” generators?

Yes, General Power offers “Tier 4 Final” generators. To browse our list of Tier 4 Final generators, please visit our Tier 4 Final Generators category page.

Does General Power offer “Export Only” generators?

Yes, General Power offers “Export Only” generators. To browse our list of generators available for export, please visit our Export Only category page.

Does General Power offer Stationary Emergency generators?

Yes, General Power offers Stationary Emergency generators. To browse our Stationary Emergency generators, please visit our Emergency Generators category page. If you need help with generator selections, get immediate assistance by calling our team at 1-833-428-0674 for immediate assistance.


1. https://www.epa.gov/

2. https://nepis.epa.gov/Exe/ZyPDF.cgi?Dockey=P100OA05.pdf

3. https://www.epa.gov/vehicle-and-engine-certification/transition-program-equipment-manufacturers-tpem

4. https://www.ecfr.gov/cgi-bin/text-idx?SID=5bd49186c6de428e7d6446a56baab96c&mc=true&node=pt40.36.1039&rgn=div5#se40.36.1039_1101

5. https://www.govinfo.gov/content/pkg/CFR-2010-title40-vol32/pdf/CFR-2010-title40-vol32-sec1039-625.pdf

Powered by Top Rated Local®