The U.S. Environmental Protection Agency (EPA) published new rules in February 2024 that limit methane (CH4) and volatile organic compound (VOC) emissions from the onshore oil and natural gas (O&G) industry. The rules are known as NSPS OOOOb and EG OOOOc. These rules will go into effect 60 days after publication in the Federal Register.
- NSPS OOOOb targets new O&G facilities constructed, modified, or reconstructed after December 6, 2022.
- EG OOOOc is a guide for states regulations for O&G facilities existing on or before December 6, 2022. These state regulations must be as stringent as OOOOc, which are very similar to OOOOb. States may have up to 5 years to implement these rules.
The EPA’s new rules, NSPS OOOOb and EG OOOOc, aim to reduce methane (CH4) and volatile organic compound (VOC) emissions from the onshore oil and natural gas (O&G) industry.   The new EPA rules, which will go into effect 60 days after publication in the Federal Register in 2024, require operators to invest in and operate Enclosed Combustion Devices (ECDs) under stricter standards. Understanding the specific requirements for ECDs, including testing, operation, monitoring, and NHV compliance, is crucial for ensuring facilities remain compliant.  In this article we examine the compliance requirements for ECDs as outlined in NSPS OOOOb and EG OOOOc, and introduce Cimarron’s certified combustion solutions with integrated continuous monitoring.
Link to EPA OOOOb Final Rule Information
ECDs as Control Devices for OOOOb Emission Sources
The following emission sources use ECDs as emission control devices under OOOOb and OOOOc.
- Tank battery storage tanks for crude oil, condensate and produced water
- Facility blowdown events (to prevent a super-emitter event)
- Associated gas from oil wells
- Centrifugal and reciprocating compressors seal venting
- Liquids unloading venting
- Pneumatic devices using natural gas
Performance Testing ECDs
Oil and gas facilities have two options for using enclosed combustion devices (ECDs) to comply with OOOOb and OOOOc emission control requirements. These include:
- Manufacturer-Tested ECDs:
- Choose ECD models tested by the manufacturer using methods approved by OOOOb.
- Find a list of approved models on the EPA website (LINK).
- Specific requirements for using these ECDs are outlined in 40 CFR 60.5413b(d).
- Non-Manufacturer-Tested ECDs:
- Conduct an initial field performance test within 6 months of starting operation.
- Repeat the test every 5 years (60 months) thereafter.
- Conduct a new test if you want to increase the inlet gas flow rate.
- Detailed testing requirements are found in 40 CFR 60.5413b(b).
Both tests must demonstrate a control efficiency of equal to or greater than 95%.
This discussion pertains to manufacturer tested ECDs.
ECD Operating Requirements
- A pilot or combustion flame must be present at all times of operation.
- Must operate with no visible emissions.
- Operate at or above the manufacturer determined minimum inlet flowrate.
- Operate at or below the manufacturer determined maximum inlet flowrate.
- Maintain the ECD in a leak free condition.
- Operate according to the manufacturer’s written operating procedure and maintenance schedule.
For each of these operating requirements, records must be maintained for at least 5 years.
ECDs using pressure-assisted burner tips to promote mixing at the burner tip do not have to operate ECD at or below the maximum inlet flowrate.
ECD Monitoring Requirements
- Continuously monitor for a pilot or combustion flame.
- a. Record a reading at least every 5 minutes.
- b. Send alerts to the nearest control room whenever the pilot or combustion flame is unlit.
- Continuously monitor inlet gas flowrate. Record a reading at least every 1 hour.
- Monthly monitor for visible emissions using EPA Method 22. Maintain records of testing.
- After maintenance or repair activity, each ECD must pass a Method 22 visible emissions test.
NOTE: Since Cimarron’s ECDs do not use combustion zone temperature as an indicator of destruction efficiency, OOOOb and OOOOc do not require combustion zone temperature monitoring.
There are exceptions in OOOOb that do not require ECD inlet flowrate measurement. These require certain backpressure valves or engineering determinations.
ECD Continuous Parameter Monitoring Plan
A monitoring plan is required for each emission control device. The facility must install, calibrate, operate, and maintain each continuous parameter monitoring system in accordance with the monitoring plan. The monitoring plan should include:
- System performance criteria and design specifications.
- Sampling interface (e.g., thermocouple) location for representative measurements.
- Equipment performance checks and system accuracy audits.
- Ongoing operation and maintenance procedures.
- Recordkeeping
Consult the section above titled “ECD Monitoring Requirements” for details on the parameters that need continuous monitoring.
The facility must conduct performance checks, system accuracy audits, or other audit procedures specified in the monitoring plan at least once every 12 months.
Heat sensing monitoring devices that indicate the continuous ignition of a pilot or combustion flame are exempt from the calibration, quality assurance and quality control requirements.
Net Heating Value (NHV) of ECD Inlet Gas
For manufacturer tested ECDs, the inlet gas must have a net heating value (NHV) of the gas as shown below. For certain applications, periodic or continuous monitoring of NHV may be required by OOOOb.
Continuous NHV monitoring is not required for inlet gas that is only associated gas from a well with high enough NHV.
Initial ECD inlet vent gas NHV testing options include:
- Facilities can demonstrate the inlet gas to the ECD (except steam-assisted and air-assisted ECDs) meets or exceeds the NHV requirements in above Table 1 using a 14-day sampling/chemical analysis program. A minimum of 28 samples are required. This periodic sampling and chemical analysis are required once every 5 years.
- Continuously measure Btu of inlet gas using a calorimeter, gas chromatograph, mass spectrometer, or grab sampling and chemical analysis of the vent gas.
- For ECDs, continuously monitor exhaust gas to verify total organic carbon (TOC) concentration is less than or equal to 275 ppmv (as propane).
For unassisted or pressure-assisted ECDs or flares that initially demonstrate the vent gas combusted consistently exceeds the NHV requirements, no continuous measurement of the NHV of gas required. For these tanks, the facility must collect three inlet gas samples once every 5 years and chemically analyze to demonstrate the NHV is sufficient.
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Summary and Conclusions
The EPA’s new rules, NSPS OOOOb and EG OOOOc, aim to reduce methane (CH4) and volatile organic compound (VOC) emissions from the onshore oil and natural gas (O&G) industry. This blog post specifically examines the compliance requirements for enclosed combustion devices (ECDs) used to meet these emission limits.
ECDs are used to comply with emission limits since they can easily meet the required 95% control efficiency.
Two options exist for demonstrating compliance: using manufacturer-tested ECDs or conducting field performance tests. Specific operating and monitoring requirements apply to all ECDs, with records kept for at least 5 years. The net heating value (NHV) of the inlet gas must meet certain criteria based on the ECD type.
Several options exist for demonstrating compliance with NHV requirements, including periodic sampling and analysis or continuous monitoring.
The new EPA rules represent significant changes for O&G facilities, requiring them to invest in and operate ECDs to meet stricter emission standards. Understanding the specific requirements for ECDs, including testing, operation, monitoring, and NHV compliance, is crucial for ensuring facilities remain compliant. The blog post provides a helpful overview of the key requirements but emphasizes consulting the full EPA rules and seeking expert guidance for detailed implementation.
Cimarron – Who We Are
With decades of operating history and innovation across our trusted brands, Cimarron provides technology-driven emissions management solutions for the global energy system. Our leading-edge products, services, and real-time monitoring systems reduce emissions, optimize operations, ensure regulatory compliance, and drive sustainability progress for our customers operating in oil & natural gas production, energy storage & distribution, renewables & biogas, coal mine methane, and certain industrial end markets.
Cimarron boasts a collection of well-established technologies which have been assembled and innovated from trusted industry brands. Our vast global experience, spanning tens of thousands of equipment installations, serves as a testament to our ability to achieve success in every project upon which we embark.
Cimarron is headquartered in Houston, Texas with approximately 550 employees serving our global customer base. In addition to being present in all major regions in the U.S., Cimarron operates across more than 45 countries around the world. We support our customers from sales, engineering, manufacturing, and field service locations across the United States, Italy, India, England, and the United Arab Emirates, further supported by our network of international partners.
Please contact us to learn more about our products and services and about all our solutions at sales@cimarron.com or visit our website www.cimarron.com.