Hi Flow 2 - Meeting and Exceeding the High Volume Sampler Demands of OOOOb

HI-FLOW 2 – Meeting & Exceeding the High-Volume Sampler Demands of OOOOb

June 19, 2024

By: David Booker, CTO, Sensors Inc.

A high-volume sampler that complies with OOOOb and ACR methodologies

The Sensors Emissions Measurement Technology (SEMTECH) HI-FLOW 2 is a battery-powered, handheld high-volume sampler that uses cutting-edge flow and gas sensing technologies for the direct quantification of leaks in the 0.0005 to 25 CFM (0.015 to 700 lpm) range with accuracy within 5%.

However, just as important as highly accurate leak quantification, the HI-FLOW 2 also meets the demands of the EPA’s OOOOb.

OOOOb demands

Leak detection (range)

OOOOb states that flow measurement devices must “have a measurement range over the entire expected range of flow rates sampled.” Additionally, these devices are required to have a measurement range over “the entire expected range of concentrations.”

The HI-FLOW 2 offers a best-in-class dynamic range of 0.0005 to 25 CFM. This is a very large dynamic range that encompasses the expected range of sampled flow rates and concentrations.


OOOOb demands that the gas concentrations and flow rates are accurately within 5%. The HI-FLOW 2 is manufactured to meet a higher accuracy of 2.5% for both components. Additionally, OOOOb requires:

  • 3 separate 1-minute measurements are collected to determine a leak’s average leak rate. The difference between these samples must be less than 10%
  • Methane gaseous calibration cylinder standards are used to challenge each sensor prior to and at the end of a testing day
  • The cylinder value and a sensor reading must be less than 5% in difference of the respective calibration gas value at each point
  • If the check fails at either point, the data from all tests performed prior to the previous passing calibration check must be invalidated

The HI-FLOW 2 comes with web-based software that generates reports in full compliance with OOOOb. All metrics associated with sensor testing, measurements, and leak detection are collected and formatted for appropriate report submission.

Regarding field testing, the HI-FLOW 2 has easily demonstrated compliance to the requirement that the relative difference between the three 1-minute measurements is less than 10%. And the HI-FLOW 2’s in-unit software delivers linearity performance validation and compliance information.

Design criteria for gas concentration measurement

According to OOOOb: “The methane sensor(s) must be selective to methane with minimal interference, less than 2.5 percent for the sum of responses to other compounds in the gas matrix. You must document the minimal interference though empirical testing or through data provided by the manufacturer of the sensor.” Moreover, the sensors must be linear and capable of meeting a maximum 5% accuracy criteria.

The HI-FLOW 2 meets NIST traceable certification to <2.5%:

GasBottle value (ppm)Measured CH4 (ppm)Interference (%)Pass/Fail

Annual calibration requirements

OOOOb requires that flow measurement sensors are calibrated annually. As shown in Sensors, Inc.’s calibration certificates, the HI-FLOW 2 is calibrated annually:

Methane Analyzer Linearity Results

Intercept-0.013%+/- 1% maxPass
Slope0.9960.975 – 1.025Pass
SEE0.233%+/- 1% maxPass

Additionally, sensors receive initial calibration for linearity and accuracy to 2.5%. This initial calibration is checked every 12 months and bi-annually to 5% criteria.

DescriptionTest dateDue datePass/Fail
Methane sensor Linearity and accuracy (2.5% criteria)March 14, 2024Initial installation or every 12 monthsPass
Methane Sensor span and dilution calibrationMarch 14, 2024Initial installation or every 12 monthsPass
Methane sensor noiseMarch 14, 2024Initial installation or every 12 monthsPass
Methane sensor interferencesMarch 14, 2024Initial installationPass

This calibration schedule meets OOOOb’s initial and semi-annual calibration requirements.


According to OOOOb, fugitive emissions monitoring plans and survey records must include the “training, and experience of the operator(s) performing the survey.”

Distributors of the HI-FLOW 2 handle the training of device operators. They ensure that each operator meets the mandated training requirements of OOOOb, completely removing this burden from facility owners. Available support resources include:

  • Service
  • Technicians
  • Commissioning
  • Software resources
  • Trained distributors
  • Consultancy

Learn more about the HI-FLOW 2 high-volume sampler

Access more information about the HI-FLOW 2, including technical specs and its ease-of-use features, at sensors-inc.com.

David Booker, CTO

David Booker, CTO, Sensors Inc.
David Booker has 35 years of experience in advanced applications. During his 20+ years at Sensors, Inc., Booker has provided technology oversight and evaluations, regulatory advisory and support, and business and product development leadership. Throughout his career, his work has been published and he has been granted several patents. He has also presented at numerous conferences and received several prestigious awards. He holds an honors degree in chemistry from Newcastle University and received a PhD in chemical engineering from Exeter University.

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