Fugitive Emission Test Procedure
What is a Fugitive Emission Test?
With over 25 years of experience in environmental monitoring, Perfect Pollucon Services is a trusted leader in fugitive emission testing across industries. Fugitive emissions refer to unintended releases of gases or vapors due to leaks in valves, seals, or equipment. These emissions are often overlooked in equipment design, making regular testing crucial to environmental compliance, safety, and sustainability.
In this guide, we share our expert insights, best practices, and common pitfalls to avoid when conducting fugitive emission tests.
Fugitive emission testing is the process of detecting and measuring unintended gas leaks from industrial equipment. These leaks can release hazardous pollutants into the environment, posing risks to human health, equipment efficiency, and regulatory compliance.
Common sources of fugitive emissions include:
- Valves (major source, nearly 60% of emissions)
- Flanges & Fittings
- Pump seals & Gaskets
- Storage Tanks & Pipelines
At Perfect Pollucon Services, we specialize in advanced leak detection methods using helium and methane as test mediums, ensuring compliance with ISO 15848, API 622, API 624, and other international standards.
Fugitive emission test procedure is performed using helium (He) or methane (CH4) gas based on the method. The term “Fugitive” is used widely because these emissions are not considered and calculated during the design of the equipment and its components.
Why is Fugitive Emission Testing Important?
Fugitive emissions are a silent but significant environmental and safety risk. Over the past 25 years, we’ve seen how neglecting leak detection leads to unexpected shutdowns, regulatory fines, and hazardous workplace conditions.
Key reasons why regular fugitive emission testing is essential:
- ✅ Regulatory Compliance: Meet EPA, ISO, and API standards
- ✅ Environmental Protection: Reduce air pollution and greenhouse gases
- ✅ Workplace Safety: Prevent accidental gas exposure
- ✅ Cost Savings: Avoid energy loss and unplanned maintenance
When is a Fugitive Emission Test Required?
It is recommended to conduct a Fugitive emission test before the installation of valves and at regular intervals to avoid leakage of hazardous gas or vapour into the environment. It can also be done in case of any incident near valves to make sure everything is fine.
What is Low Fugitive Emission (LFE) ?
As per American Petroleum Institute (API), Low fugitive emission or low leaking means either no or very minimal (100 ppm till 5 years) leakage from the valve. Please note that EPA Has not defined any standards for Low Fugitive Emissions.
Read more about Fugitive Emission Monitoring and Testing
How Do You Detect Fugitive Emissions?
There are multiple ways to detect fugitive emissions, but the method depends on the gas type, equipment design, and regulatory requirements.
Our expert-recommended fugitive emission detection methods:
- Gas Leak Detectors (LDAR Programs): Uses infrared cameras, flame ionization detectors, and VOC analyzers
- Helium Mass Spectrometry: Ideal for high-precision leak detection
- Methane Sniffing Method: Commonly used in oil & gas industries
- EPA Method 21 Compliance Testing: Required for regulatory reporting
Fugitive Emission Test Procedure
There are 4 major types of fugitive emissions test methods:
Vacuum Method
In Fugitive Emission test method helium is used as the testing medium to measure the overall leak rate from the stem seal using a helium mass spectrometer. In this procedure, the leak source is enclosed in a tight vacuum container, which is evacuated and then connected to a helium mass spectrometer.
✅ Expert Tip: “This method is best suited for low-pressure systems. However, we’ve observed that improper sealing of the vacuum chamber can lead to false positives—a common industry mistake.”
Flushing Method
In Fugitive emission test procedure, pressurized Helium or Methane is used to measure the total leak rate of the stem sealing system. The leak source is enclosed by a flush chamber, a flush gas is passed through that chamber and it is allowed to be mixed with the leaking fluid from the stem packing. Then this mixture is passed through exhaust line and based on the concentration of leak fluid and flush gas leakage volume is calculated in ppmv unit
✅ Avoid Mistake: “A common mistake in this method is not calibrating the flush gas flow rate, which can affect the accuracy of leak rate calculations.”
Learn more about Professional Air Quality Testing
Bagging Method
This is the revised version of the Flushing method and in this method, only Helium is used to measure the total leak rate using Helium Mass Spectrometer. The leak source is enclosed by a bag volume i.e. air is passed through the bag and then is mixed with leak fluid from the stem packing. This mixture is analyzed by Helium mass spectrometer through a constant flow rate detector probe or sniffer.
✅ Expert Insight: “We recommend this method for portable and on-site testing, as it provides reliable data in real-world operating conditions.”
Sniffing Method
In Fugitive Emission test procedure, Helium as fluid is used to measure Helium concentration due to emission from stem sealing and body sealing using a detector probe or sniffer. In the case of Methane as a testing fluid, the process remains the same but instead of a Helium leak detector, VOC Detector is used.
✅ Pro Tip: “For accurate detection, always use a calibrated probe and maintain a constant distance from the leak source.”
Common Mistakes in Fugitive Emission Testing
Over the past 25 years, we’ve identified some of the most common mistakes in fugitive emission testing. Avoiding these can improve accuracy and compliance:
- ❌ Ignoring Equipment Calibration – Always calibrate test equipment before use
- ❌ Overlooking Valve Packing – A worn-out valve packing can increase leakage rates
- ❌ Rushing the Test Process – Proper stabilization time ensures accurate readings
- ❌ Incorrect Probe Positioning – Keep the detector probe at a consistent distance
Fugitive Emission Test Standards:
Fugitive Emission Test Standards define the acceptable leakage rates and test methodologies for industrial equipment. Over the years, we have helped companies achieve compliance with leading standards such as:
- ISO 15848-1 & 15848-2 (Comprehensive valve testing guidelines)
- API 622, API 624, API 641 (Oil & gas industry standards for valve packing and leakage)
- EPA Method 21 (Regulatory standard for leak detection & repair)
At Perfect Pollucon Services, we provide expert guidance on selecting the right standard based on your industry needs.
Various organizations have came up with Fugitive Emissions Testing Standards such as API, EPA, ISO, MESC, ANSI, etc. to assess the performance of valve packing and valve emissions. There has been many discussions on various forums about comparison of standards from all agencies.
Amongst all Agencies, Fugitive Emission Testing Standards from API and ISO are widely used. ISO 15848 is very popular as it describes measurement, test and qualification procedures for fugitive emissions at industrial valves.
ISO 15848-1 is a classification system and a qualification procedures for type Fugitive Emissions testing of valves. ISO 15848-2 specifies production acceptance test of valves for valve manufacturer.
Below is the comparison of various prescribed fugitive emissions testing standards as per ISO and API:
| Comparison Factor | ISO 15848-1 | ISO 15848-2 | API 622 | API 624 | API 641 |
| Current Revision: | 1st 2006-01-15 | 1st: 2006-08-15 | Oct. 2nd, 2011 | In process of 1st publication | `Oct. 2016 |
| Qualifies: | Valve Design | Production | Packing | Valve Design | Valve design |
| Testing type/ Production acceptance | Type Testing | Production Accpetance | Type testing | Type testing | Type testing |
| EPA Method 21 compliant: | Yes | Yes | Yes | Yes | yes |
| Pre-Requisite: | None | ISO 15848-1 qualified valve design | None | API 622 qualified packing | API 622 qulified packing |
| Test Medium: | Helium or Methane | Helium | Methane | Methane | methane |
| Packing Tested in: | Valve | Valve | Fixture | Valve | Valve |
| Test Pressure: | Rated Valve Pressure at Test Temperature per ASME B16.34 | 6 bar (87 psi) | 0-600 psi | The lower of 600 psi or maximum allowable pressure at 500°F (260°C) per B16.34 | As per Valve group A, B, C, D, E |
| Test Temperature: | As pertemperature chart table -196°C, -46°C, Room temp. , 200°C and 400°C | Ambient | Ambient and 500°F (260°C) | Ambient and 500°F (260°C) | As per Valve group A, B, C, D, E |
| Mechanical Cycles: | For Isolating Valve: CO: 205 CO2: 1500 CO3 : 2500 For Control Valve CC1: 20,000 CO2: 60,000 CO3: 10,000 | 5 | 1,510 | 310 | 610 |
| Thermal Cycles: | Variable[1] | 0 | 5 | 3 | 3 |
| Leakage measurement Method | Vaccum, Flushing, Bagging, Sniffing, | Sniffing | N/A | sniffing | Sniffing |
| Allowable Packing Adjustments: | 1 (during testing only) | 0 | Packing adjustment allowed if leakage exceed 500 ppm | 0 | 0 |
| Measured Units: | mg/sec-m | ppm | ppm | ppm | ppmv |
| Acceptance Criteria: | As per tightness class: For stem seal: fluid helium Class AH: 10-5 mg/s-m Class BH: 10-4 mg/s-m Class CH: 10-2 mg/s-m For Stem seal: Fluid- Methane Class AM: 50 ppmv Class BM: 100 ppmv Class CM: 600 ppmv From body joint seal: 50 ppmv | For Stem seal: Fluid- Methane Class A: 50 ppmv Class B: 100 ppmv Class C: 600 ppmv From body joint seal: 50 ppmv | 500 ppm | 100 ppm | 100 ppm |
| Qualification Coverage: | Same basic design Stem Diameters: 50% lower and 200% higher. Pressure class: Same class and lower[4]. | N/A, Because each and every valve need to be tested | Packing Only | – | 1. Te, Pe, Pa valves are less than or equal to the valves specified in perticular applicable group 2. Stem diameters are from half to twice the tested valve diameter 3. height of stem seal is between 75% to 125% of existing tested valve |
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About Perfect Pollucon Services
Fugitive emission testing is critical for regulatory compliance, environmental protection, and operational efficiency. With over 25 years of expertise, Perfect Pollucon Services ensures accurate, reliable, and cost-effective emission testing tailored to your industry needs.
✅ Need expert fugitive emission testing? Contact Perfect Pollucon Services today for a free consultation!
Fugitive emission testing is the process of detecting and measuring unintended gas or vapor leaks from industrial equipment such as valves, flanges, and pump seals. These emissions can be hazardous to the environment and human health, making regular testing essential for compliance with EPA, ISO, and API standards.
Fugitive emissions contribute to air pollution, workplace hazards, and energy losses. Regular testing helps industries comply with environmental regulations, reduce greenhouse gas emissions, and ensure safe and efficient operations.
Fugitive air emissions are unintended releases of gases or vapors into the air from industrial equipment, often due to leaks, faulty seals, or improper maintenance. These emissions differ from stack emissions, which are released from controlled sources like chimneys.
A common example is methane leaks from oil and gas pipelines or valves. Other examples include VOC (Volatile Organic Compound) emissions from chemical plants and hydrocarbon leaks from refineries.
Fugitive emissions are detected using various methods, including:
Gas leak detectors (Infrared cameras, VOC analyzers)
Helium mass spectrometry (for precise detection)
Methane sniffing method (for oil & gas industries)
EPA Method 21 compliance testing
The most commonly used fugitive emission testing standards are:
ISO 15848-1 & ISO 15848-2 (for industrial valves)
API 622, API 624, API 641 (for oil & gas valve testing)
EPA Method 21 (for regulatory compliance)
The EPA’s Leak Detection and Repair (LDAR) regulations under Method 21 require industries to monitor and fix leaks from components like valves, flanges, and pumps to minimize fugitive emissions.
The four major methods used in fugitive emission testing are:
Vacuum Method (Uses helium and a vacuum chamber)
Flushing Method (Uses pressurized helium or methane)
Bagging Method (Encapsulates the leak source in a bag)
Sniffing Method (Uses a detector probe to measure emissions)
Fugitive emission testing is required in the following cases:
Before installing valves to ensure compliance
Regular intervals as per industry regulations
After maintenance or repairs to verify leak-tightness
After any incident involving potential gas leaks