It’s often said that to be successful in life, it’s necessary to find balance. And if you are in a number of industries including energy / petrochemicals, natural gas, steel mills, cement kilns, or even aircraft engine testing, there’s nothing more true than this statement when it comes to the relationship between productivity and environmental protection. To help businesses simplify and streamline this process, there exists a version of calibration gases known as EPA Protocol Gases, which are defined by the EPA as “compressed gases used to calibrate air pollution monitors for consistent and reliable monitoring”. In other words, the EPA is helping to balance our need for energy with our need for a clean and sustainable planet.
A bit about traceability
Given their role in ensuring clean air for all, it's no wonder that a number of steps are necessary to ensure their quality. All EPA protocol gases gases should have defined traceability to NIST or equivalent and should be accompanied by documentation in the form of a Certificate of Analysis (COA). Compositional traceability is determined via two key methods:
- Analytical traceability: Using reference materials to calibrate the measurement system via a meticulous process that determines the concentrations of mixture components.
- Process traceability: The use of high sensitivity weighing systems for component additions versus the international unit of mass (Kg). These are then analyzed against primary standards with known composition and uncertainty.
For EPA protocol gases, traceability must be demonstrated through Standard Reference Material (SRM) program, the NIST Traceable Reference Material (NTRM) program, the Gas Manufacturers Intermediate Standard (GMIS), and Primary Reference Materials (PRM). In other words, to be an EPA protocol gas, it must be analyzed using traceable NIST gas standards. A primary standard can be NIST traceable by weight, but that doesn’t automatically make it a protocol gas; it only becomes a protocol when analyzed using traceable NIST gas standards.
How can I ensure that my protocol gas is up to standard?
An EPA Certificate of Analysis (COA), is essential for ensuring the quality and composition of your gas blend. A standard COA contains the following:
- A clear description of the mixture in terms of requested composition and certified composition
- The items listed in section 126.96.36.199 of the EPA Traceability and Protocol for Assay and Certification of Gaseous Calibration Standards EPA 600/R-12/531 May 2012
- Mixture pressure, mixture accuracy, valve type, gas volume, and conditions for storage and use
- An explanation of traceability
- Customer order number
- Expiration date
Every gas mixture that you received should contain an EPA protocol COA. For WestAir EPA protocol gases, a COA looks something like this:
Keep in mind that should any local, state, or EPA air quality enforcement personnel have questions about your processes or compliance, a COA is one of the first things they will request. This will help them to see that your protocol gases meet current and mandatory requirements.
What are the risks associated with EPA protocol gases and how can they be minimized?
While EPA protocol gases themselves don’t carry a huge amount of risks, allowing them to expire could lead to bringing your business out of compliance; resulting in fines that could cost you thousands. It can also spell trouble practically speaking as an expired gas can be less accurate than its in-date counterpart, potentially impacting the effectiveness of your business. Thankfully, EPA protocol gases today have much longer shelf lives, so the odds of this happening have lowered considerably. Additionally, some companies even offer EPA protocol inventory programs. These programs mean that a gas supplier will hold a certain protocol gas onsite and in inventory for a customer. This means that they can consistently provide delivery within a 48 hour time frame, and oftentimes with automatic re-order included - offering peace of mind that could never have been achieved previously.
If your EPA protocol gas is in on the edge of expiration, make sure to contact us to learn about how re-certification could be the solution to your compliance needs.
Is a protocol gas the same thing as a zero gas?
It’s important to keep in mind that any EPA protocol gas should also be a zero gas in order to set an accurate zero point in your analytical instruments. For a zero gas to be acceptable by EPA it should meet the requirements as set out in 40 CFR 72.2, EPA CFR 40 Part 60 EPA test methods, and EPA CFR 40 Part 75. Additionally, any zero gas that will be used for EPA purposes should be free of the following:
- Concentrations of NOx, SO2 and/or total hydrocarbons above 0.1 parts per million (ppm)
- A concentration of CO above 1 ppm
- A concentration of CO2 above 400 ppm
Another differentiator can be found in the utility of the protocol gas itself. Depending on the source of the emissions, EPA protocol gases are used to measure a number of different components. For example, if it is a boiler or a heater that requires compliance, a protocol gas is used to measure carbon monoxide, nitrogen oxides, and oxygen concentration.
Which EPA protocol gas do I need?
Depending on what the source of pollutants is, different test methods, and as such different protocol gases, are required. One of the most common test methods is defined by 40 CFR Part 75 and 60, which helps to measure waste from smokestacks and industrial sources.
The table below outlines EPA Instrumental Test Methods that are further defined by 40 CFR Part 60:
|EPA METHOD||DETERMINES||COMPONENTS TESTED||ZERO GAS|
|3A||O2% and CO2%||
O2 and/or CO2 in N2 or mixtures of SO2 ppm and/or NO2 and O2% and/or CO2% in N2
|Defined by CFR 40 72.2|
|3 & 3B||O2% and CO2% using an ORSAT||CO2, CH4, N2, O2, and other gas components||-|
|3C||O2 and/or CO2 in N2 and CH4 ppm using Thermal Conductivity gas chromatograph||CO2, CH4, N2, O2, and other gas components||Carrier gas: He, high purity|
|6C||SO2 ppm from stationary source||
SO2 ppm in air or N2
SO2 ppm and/or O2% nd/or CO2% in N2
|Defined by CFR 40 72.2|
|7E||NOx ppm from stationary sources||NOx ppm in N2, NO2 for converter efficiency||Defined by CFR 40 72.2|
|10A||CO ppm CEM at petroleum refinery||CO ppm in N2||Defined by CFR 40 72.2|
|10||CO ppm from stationary sources||CO ppm in N2||Defined by CFR 40 72.2|
|10B||CO ppm from stationary sources||CO ppm in N2 and CH2 in air||(He zero / H2 zero)|
|15A||TRS emissions from sulfur recovery plants in petroleum refinery||COS in N2||<50 ppb TRS with <10 ppm hydrocarbons|
|15||TRS emissions from sulfur recovery plants in petroleum refinery||H2S in N2 and COS in N2 and CS2 in N2 traceable||<0.5 ppm TRS with <10 ppm H2O and (O2 zero/zero N2)|
|16||TRS emissions from kraft pulp mills||H2S in N2 and MeSH in N2 and DMS in N2 and DMDS in N2 traceable||<50 ppb TRS with <10 ppm hydrocarbons|
|16A||TRS emissions from kraft pulp mills||H2S in N2||<50 ppb TRS with <10 ppm hydrocarbons|
|16B||TRS emissions from kraft pulp mills||SO2 in N2 and H2S in N2||<50 ppb TRS with <10 ppm hydrocarbons|
|18||Gaseous organic compound emissions by gas chromatography||VOC ppm in N2 <1-2% or NIST traceable||Defined by CFR 51 Appendix M Method 205|
|21||Volatile Organic Compound (VOC) leaks||VOC ppm in N2 or air <2%||<10 ppm VOC|
|25||Total Gaseous Non-methane Organic Emissions (TGNMO) as carbon||CO, CH4, C3H8, CO2, C6H14, C7H8, and CH3OH each in air <1%||He, air and O2 <1 ppm HC and CO2 <1 ppm & <0.1 ppm HC|
|25A||Total gaseous organic emissions using FID||C2H6, C3H8, C4H10 or appropriate in N2 or air <2%||Defined by CFR 51 Appendix M Method 205|
|25B||Total gaseous organic emissions using NDIR||C2H6, C3H8, C4H10 or appropriate in N2 or air <2%||Defined by CFR 51 Appendix M Method 205|
|25C||Non-methane Organic Compounds (NMOC) in MSW landfill gases||CO, CH4, C3H8, CO2, C6H14, C7H8, and CH3OH each in air <1%||<10 ppm VOC|
|25D||Volatile organic concentration of waste samples||% C3H8 and % C2H2Cl2 in N2||N2, air and O2 <1 ppm C|
|25E||Phase organic concentration of waste samples||% C3H8 in N2 or air NIST traceable||N2, air and O2 zero grade <ppm C|
|30A||HG0 μg/m3 from stationary sources||Hg0 & HgCl2 μg/m3 in N2 or air NIST traceable||No measurable Hg|
|30B||HG0 μg/m3 from stationary sources||Hg0 & HgCl2 μg/m3 in N2 or air NIST traceable||No measurable Hg|
Regardless of which protocol gas you need, there are a few standards that are essential to achieve, outlined below:
Accuracy: Broadly speaking, accuracy is defined as the statistical agreement of a measured value with its true value. It is calculated using the propagation of error model using the most common error factors, which are:
- Reference standard error
- Measurement precision
- Stability factor
- Precision of analytical instrument used
- Accuracy of any gravimetric systems
- Human error
Blend tolerance: This is the degree of agreement between the actual concentration and the requested concentration. A number of factors can influence tolerance, such as blending method, component reactivity, and raw material impurities. See section below for a bit more information on tolerance and how it can be determined.
Production speed: Once the end user has determined the specifications of the gas needed, the production process begins. The vendor will follow the necessary laboratory and production procedures, be it a custom mix or a standard mix. From start to finish, this process should take no more than 25 working days. For those who already have EPA protocol gases in stock, but need to ensure that they are meeting compliance standards, re-certification is one of the fastest ways to do so.
Stability: Maintaining a consistent concentration value over a defined time is an essential component in blend stability. It can be affected by a number of factors including:
- Component reactivity
- Cylinder pressure
- Raw material purity
- Cylinder / valve material
- Delivery system
- Internal cylinder preparation
Expert advice: Having a team that is experienced not only in gas blending, but also in your chosen industry can be a game changer. As such, when you are choosing an EPA protocol gas provider, be sure to find a vendor who is certified under the EPA’s Protocol Gas Verification Program and also experienced in your industry in particular.
Understanding different blend tolerances
As mentioned briefly above, blend tolerance is the difference between the blended concentration and the requested concentration. Unlike blend accuracy, blend tolerance is not determined by statistical means.
Preparation tolerance is the minimum acceptable uncertainty associated with the actual production of the blend. These types of uncertainties are measured in range of concentration and can be minimized by using the latest technologies to manufacture gas blends. Also referred to as ‘blending tolerance’.
Certification tolerance also called ‘analytical tolerance’, this is the minimum acceptable uncertainty associated with the analysis of the blend. Unlike preparation tolerance, this uncertainty is accumulated during the analytical process and includes uncertainties related to instruments and calibration.
In many cases, certification (analytical) tolerance is more important than preparation (blend) tolerance. This is because it gives the range that an actual concentration may be in, relative to the analytical concentration. There are some applications where preparation tolerance become more important - usually in those that require an upper or lower range of concentration.
How can WestAir help your business?
As part of our ongoing effort to supply the highest quality gases, WestAir is now ISO 17025:2017 certified for both gas analysis and the calibration of analytical equipment to safeguard the quality of the products that are important to you.
This certification also enables us to be approved under the EPA’s Protocol Gas Verification Program (PGVP). Such verification helps us to give our customers peace of mind to know that their protocol gases are of the highest quality and consistency. Some industries that we are currently serving under this need include:
- Chemical plants
- Cement producers
- Power plants
- Stack testers
We believe that our deep experience across these industries and more empowers us to help our customers achieve EPA compliance with minimal stress. If obtaining new EPA protocol gases or re-certifying expired gases is something that your business may be in need of, contact us and an experienced WestAir EPA protocol gas professional will be in touch within 1 business day to help you begin.
Can’t wait that long? Give us a call directly at 866 937 8247