LDAR Options for Pegged Emission Rates and Analyzers

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Note: This article will outline the options available to LDAR (Leak Detection and Repair) programs regarding pegged emission rates and analyzers, focusing on valves in light liquid/gas vapor service. The information is prepared solely for your consideration. LDARtools does not provide regulatory advice or guidance.

Originally published by Fugitive Emissions Journal 10/02/2024.

Definitions and Background

Pegged Emission Rate – The specified emission rate used for any leak with a “pegged” screening value (i.e., any PPM reading exceeding the Analyzer Peg Value).

 

Analyzer Peg Value – The highest PPM reading an analyzer is designed to detect.

 

When a PPM reading is higher than the Analyzer Peg – “The instrument measurement may exceed the scale of the instrument, referred to as a ‘pegged’ readout. For several instruments, the highest readout on the scale is 10,000 ppmv. For generating an emissions estimate, a dilution probe should be employed to measure concentrations greater than the instrument’s normal range unless average emission factors for greater than or equal to the ‘pegged’ readout are applied. Extending the measurement range necessitates calibrating the instrument to the higher concentrations.” (From section 2.3.3 of the 1995 Protocol for Equipment Leak Emission Estimates).

 

Calculation of Emissions Using Correlation Equation

To estimate emissions using the EPA Correlation Approach, measured concentrations (screening values in PPM) for each component are individually calculated by applying the PPM reading to a specific Correlation Equation, specified for that component type and physical state.

 

How it works: There are three possible scenarios in calculating emission for a specific component.

  1. If there is no actual inspection available (represented in PPM), then you must use the Average Emission Factors provided by the EPA for the component type and physical state.
  2. If there is an inspection available (represented in PPM), and the PPM reading is lower than the Analyzer Peg Value, you must use the specific Correlation Equation provided by the EPA for that component type and physical state.
  3. If there is an inspection available (represented in PPM) and the PPM reading is equal to or greater than the Analyzer Peg Value, then you must use the Pegged Emission Rate for that component type and physical state. This Pegged Emission Rate inevitably results in a significantly higher emission rate than would the Correlation Equation calculation (#2, above).

For an analyzer with an Analyzer Peg Value of 10,000 PPM, any reading above 10,000 ppm can be easily calculated using the 10k PPM Pegged Emission Rate. Similarly, for an analyzer that pegs at 100k, use the 100k Pegged Emission Rate (potentially subject to the calibration requirements below).

Considerations for Different Analyzer Peg Values

If you have an analyzer with an Analyzer Peg Value of 30k or 50k, it would be prudent to use the correlation equation up until that pegged value, and then use the 100k pegged value above it. However, this approach may result in an increase in reported emissions.

Example: Using an analyzer with a 30k pegged emission rate:

  • PPM value is 30,001 (a pegged reading).
  • 100k emissions factor converted back to ppm is 2.6 million ppm.
  • If using a 10k ppm analyzer peg, emissions reported would be about 912,000 ppm.

Converting mass back to ppm is not considered best practice, but is used here for illustration purposes.

Increased accuracy of reporting for components leaking between 10k and the analyzer peg value is a benefit of using a 30k or 50k analyzer peg, but pegged values could significantly increase reported emissions.

 

Questions

Do you need to calibrate to the Analyzer Pegged Value?

Maybe. The 1995 Protocol states: “The instrument measurement may exceed the scale of the instrument, referred to as a ‘pegged’ readout. A dilution probe should be employed for concentrations beyond the instrument’s normal range unless average emission factors for greater than or equal to the ‘pegged’ readout are applied. Extending the measurement range necessitates calibrating the instrument to higher concentrations.”

Since “higher concentrations” are not defined, one interpretation is to use the highest available concentration for calibration, which for methane is ~25k ppm in air (above which it becomes explosive).

Another option is to have a factory calibration done annually at 100,000 ppm. This calibration would persist during routine daily calibration.

 

What is my Analyzer Peg Value?

The 1995 protocol was developed with analog analyzers that could not exceed the meter dial’s printing. Modern analyzers use dynamic ranging to extend the upper limit significantly, but accuracy and linearity above 10,000 ppm (except for phx42) are uncertain, especially without higher value calibration.

The 2011 & 2015 protocols state: “If the monitoring instrument measures concentrations only up to 10,000 ppmv or 100,000 ppmv, the applicable values for pegged emission rates in Table 2-2 (below) are used to estimate emissions.”

 

Factors Determining Max Reliable PPM

  1. Hardware on the Circuit Board: This chip reads minimal current from the detector. Better accuracy at low ppms generally means a lower max reading before saturation. Analyzers impacted: All.
  2. Software Controlled Max PPM Value: Possible for phx42 but not implemented.
  3. Lack of O2 to Maintain Flame: For sample pumps providing combustion air (assuming methane), the limit is ~50k ppm. Linearity is impacted below this, and calibration to a higher value like 25k ppm can somewhat correct for this for values below the calibration point. Analyzers impacted: phx21, TVA1000b, and TVA2020.
  4. Detector Temperature Max: Prevents Teflon inside the detector from overheating; this only applies to phx42. The limit will not initiate shutdown until well over 100k ppm for some time.

 

Specifications from Common Manufacturers (as of 07/29/24)

TVA1000b:

  • Dynamic Range: 5-2,000 ppm (PID) isobutylene; 0.5-50,000 ppm (FID) methane
  • Linear Range: 5-500 ppm (PID) isobutylene; 0.5-10,000 ppm (FID) methane

TVA2020:

  • FID Instrument: ±10% of reading or ±1.0 ppm, from 1.0 to 10,000 ppm
  • Dynamic Range: 5-2,000 ppm (PID) isobutylene; 0.5-50,000 ppm (FID) methane
  • PID Instrument: ±20% of reading or ±0.5 ppm, from 0.5 to 500 ppm
  • Concentration: FID: 0-30,000 ppm (methane); PID: 0-2,000 ppm (isobutylene)

PHX21:

  • Range: 0-50,000 ppm Methane

phx42:

  • Range: 0-100,000+ ppm Methane
  • When calibrated to Zero and 25,000ppm Methane, 15% accuracy is maintained at 100,000ppm.
  • Annual Factory Calibration is available for 100,000ppm. A factory calibration will not be overwritten by daily calibrations in the lower spans.
  • Higher linear performance due to combustion air scrubber and second pump preventing oxygen displacement in combustion air.

Conclusion

End Users must determine the digital equivalent to “off scale,” “measures,” and the necessary calibration requirements. These decisions will determine what to select for your Analyzer Peg Value.

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Winter Weather Update for 1/22/2025

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Due to winter weather in the Houston area, our home office in Dickinson will be closed Wednesday morning (1/22) until 12:00 PM.

Support responses might also be delayed.

Please call 877-788-1110 x 6 before coming to the office to pick up or drop off.

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Winter Weather Advisory for 1/21 – 1/22/2025

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Due to winter weather in the Houston area, our home office in Dickinson will be closed Tuesday 1/21 and may also be closed Wednesday 1/22.

Support responses might also be delayed.

Please call 877-788-1110 x 6 before coming to the office to pick up or drop off.

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phx21 End of Service

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Effective January 1, 2025, we will no longer repair phx21s, or make them available for rent. If you have a phx21 requiring repairs, please request an RMA by 12/31/24, and we will repair it if the required parts are available.

For now, we will continue to support phx21 troubleshooting through hardware issues, and supply the following parts for level 1 repairs while supplies last:

LPN Part Name
766 Glow Plug
1016 Probe Quick Connect
1157 Thermocouple
1163 Pump Assembly
1541 Batt. Connection Harness

Since the phx21 made its debut in 2008, LDARtools has worked to produce high-quality products and services for our customers. With 1,219 phx21s and 17 Brownie Celebrations (no machines in for repair) later, we say a fond farewell as the era of the phx21 draws to a close.

We look forward to our continued support of your LDAR programs with the phx42 and Chateau.

Please contact sales@ldartools.com if you need assistance with a quote.

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Celebrating Chateau with 1,000 Users and Counting!

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The achievement of 1,000 users is not just a number; it’s a reflection of the trust and satisfaction of our community.

Our users come from various industries, each utilizing Chateau to streamline processes, boost productivity, and achieve their goals. It is this diversity and the success stories of our users that drive us to keep pushing boundaries and setting new standards.

Chateau’s growth is not merely about numbers; it’s about the stories and the successes of our users. With a focus on delivering the best possible service, our platform has evolved significantly over time. Each update and feature has been carefully crafted to enhance user experience, ensuring that Chateau remains at the forefront of the industry. We’ve listened to user feedback and made continuous improvements, resulting in a platform that is both user-friendly and highly functional.

Click here to receive celebration stickers!

You can also email sales@ldartools.com with the following information:

  1. City, State  ZIP
  2. Street Address Line 1
  3. Street Address Line 2
  4. Complete shipping address (cannot be a PO Box)
  5. Email address
  6. First and Last Name
  7. Site ID or Company Name
  8. Number of stickers requested at your site

Thank you for being part of the Chateau community. Here’s to your continued success—and to reaching new milestones together!

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New Monthly Webinar Series: Chateau Connect

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Exciting News from LDARtools!

 

We are thrilled to announce our new monthly webinar series, Chateau Connect, dedicated to all things Chateau! Through Chateau Connect, we will provide all of you with a quick-dive into various Chateau topics each month. The purpose of this webinar, of course, is to not only improve your experience using Chateau, but to also show Chateau’s full capabilities in the world of LDAR database software. With this being our first webinar in the series, we would love to have you join us!

 

If you are a current Chateau user, you should have received a registration link in your inbox. If you do not see the email, please reach out to sales@ldartools.com. We look forward to seeing you there!

 

And if you are not a Chateau user but are curious as to what our new monthly webinar series will entail, you can get a sneak peek by booking a no pressure meeting with our Client Success Specialist.
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Closed for Labor Day

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LDARtools will be closed Monday September 2, 2024 in recognition of Labor Day.

We will be conducting normal business operations Friday August 30 and Tuesday September 3.

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New Chateau Onboarding Setup Pricing Structure

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Price increases are not surprising. In spite of rising prices for virtually everything we need, we have continued to invest in making our products the most innovative and valuable tools for the LDAR industry.
Effective August 13, 2024, all new Chateau quotes will include a Chateau Set-up/Import Fee to cover the cost of basic imports. All existing quotes will be honored with POs received before September 1, 2024, or the quote expiration date.

 

If you have any questions, please feel free to contact sales@ldartools.com.

 

Through it all, we appreciate your business.
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Negative PPM and Smarter Portable FID Calibration

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Negative Flameout Values

A recent firmware update addressed the representation of negative values in the phx42 FID analyzer, also commonly known as a Toxic Vapor Analyzer or TVA*. Negative values always indicate a flame-out condition, where the FID is not detecting any VOCs due to a lack of ignition. The firmware update ensures these negative values are represented in a specific manner, avoiding confusion and ensuring accurate readings. The specific negative value displayed indicates the reason the phx42 is not ignited.

*This is a misnomer, but also a term the industry has accepted to describe portable FIDs.

Reading Error Message
-40 “Pump at max power for too long, report the issue.”
-41 “Probe Flow is blocked. Check Probe/ Change Filter.”
-42 “Feels like you just removed my filter. Please give me a fresh filter so we can get back to work.”
-45 “Looks like we just found a high PPM leak. Wait 30 seconds and reignite me. (Chamber overtemp)”
-46 “Trying to ignite! If 3rd attempt fails, report the issue.”
  • Note: Most monitoring applications show this text as a popup.

 

Contamination During Calibration

When any analyzer is calibrated, any contamination from previous days leaks that burns off during the day can cause the readings to shift slightly. This is a linear shift across the scale. That is to say, 1 ppm (parts per million) of contamination is burned off, it will reduce ambient by 1 ppm as well as 10,000 ppm.

Previously, if the phx21 detected a value below the zero-calibrated level, it would enter a pattern of alternating 0.0 and 0.1 readings. This pattern was implemented to avoid displaying a negative value, which is not possible in practical scenarios as readings cannot be less than 0 ppm. This would result in lower readings throughout the calibration scale. All portable FIDs at the time could experience this drift, resulting in lower readings throughout the day as well as during drifts.

 

Calibration Adjustments to the phx42

When the phx42 is calibrated under contaminated conditions and then later burned off, causing the ppm level to drop below 0 for more than 1 minute, the calibration table is edited in real-time. This adjustment is crucial for maintaining accuracy, as it corrects all the calibration points for any leftover VOCs which may have affected the calibration process and are no longer impacting the machine.

Conditions must be met for this adjustment to take place. The firmware monitors multiple conditions to ensure the machine is ignited and running properly. If a flame out/reignition occurs, the calibration table will revert to the original version to prevent an outside factor, like a probe or filter change, from impacting this feature (the phx42 will shut down during filter or probe changes). If, after reignition, the ppm returns to negative for the required time, adjustments will be made again as appropriate.

 

Practical Implications

In the older portable FID models—including phx21, TVA1000, and TVA2020—negative drift would cause interruptions, requiring work stoppage, recalibration, drift failures, and rework. The phx42, with its improved firmware, eliminates these issues by ensuring readings never fall into negative territory and that accuracy is maintained.

 

Conclusion

The phx42 portable FID by LDARtools is an advanced instrument for VOC detection, with sophisticated firmware to handle calibration and negative values efficiently. By continuously improving its firmware, LDARtools ensures the phx42 remains a reliable and accurate tool for environmental monitoring, minimizing the need for manual interventions and providing consistent accuracy.

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phx42 Operations Update: Service Interruption Resolution

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We recently encountered an issue with some phx42 units due to an update on 7/14/2024 of a third party tool used for sending settings.

 

This update started truncating decimal places for numbers controlling temperature compensation, which has the potential to impact flame stability and make drift assessments challenging. We have identified and resolved the problem.

 

Immediate Action Required:

 

For SpanBox Users:
Ensure your SpanBoxes are online using the Test Network Connection feature before calibration. If you have already calibrated and are unsure if your SpanBox was online at the time, connecting with the phxApp and running a self-check as soon as practical is advised.

 

For Non-SpanBox Users:
Run a self-check as soon as practical.

 

We sincerely apologize for the inconvenience and understand its impact. We are committed to implementing preventative measures to avoid future occurrences by transitioning away from this third party tool to a service with which we maintain and can control updates.

 

Thank you for your understanding and cooperation.
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