QA101: 40 CFR 58 App. A Gaseous Pollutants
Glenn Gehring, Technology Specialist III
Institute for Tribal Environmental Professionals
glenn.gehring@nau.edu
Voice: 541-612-0899
http://www4.nau.edu/itep/
http://www4.nau.edu/tams/
40CFR Part 58 Appendix A
The Code of Federal Regulations
(CFRs) are dynamic; always check
to be sure you have the latest
information.
CFR Title 40 Part 58 Appendix A
3.2.1 One-Point Quality Control Check for SO2, NO2, O3, and CO. A one-point quality
control (QC) check must be performed at least once every 2 weeks on each automated
analyzer used to measure SO2, NO2, O3and CO. … The QC check is made by challenging the
analyzer with a QC check gas of known concentration (effective concentration for open
path analyzers) between 0.01 and 0.10 parts per million (ppm) for SO2, NO2, and O3, and
between 1 and 10 ppm for CO analyzers.
3.2.1.1 Except for certain CO analyzers described below, point analyzers must operate in
their normal sampling mode during the QC check, and the test atmosphere must pass
through all filters, scrubbers, conditioners and other components used during normal
ambient sampling and as much of the ambient air inlet system as is practicable. …
3.2.1.3 Report the audit concentration … of the QC gas and the corresponding measured
concentration … indicated by the analyzer. The percent differences between these
concentrations are used to assess the precision and bias of the monitoring data as
described in sections 4.1.2 (precision) and 4.1.3 (bias) of this appendix.
Inside the Monitoring Shelter
Vertical
manifold
Toxics Flow
Controller
Tubing for
NOy
Gas Analyzer Rack
NOy
Continuous
Particulate
Sensor Unit
Data Logger
Calibrator
NOx
316 Stainless
Steel 1/8 inch
tubing
connects
regulator to
calibrator
SO2
Continuous
Particulate
Monitor
Control Units
Zero Air
Generator
Ozone
CGA
660?
Fitting
must
match
bottle
EPA Protocol Gas
Calibration System Pneumatics
Don’t pressurize analyzers; you must vent.
Total flow from calibrator must exceed
combined analyzer demand
Zero Air
Calibration Manifold – may have one on calibrator
Vent
Calibrator
Regulator
(2 stage stainless steel
match fittings & purge
CGA 660)
B
o
C
t
a
t
l
l
e
EPA Protocol Gas
Most have 2-year
certification
Cal gas
must pass
through filter
Analyzer
Analyzer
Analyzer
Exhaust manifold
Insect screen
Wall
What is Zero Air?
From QA-Handbook – Vol – II (Redbook):
Zero Air Systems: Zero air systems should be able to deliver 10 liters/min of air
that is free of ozone, NO, NO2, and SO2 to 0.001 ppm and CO and nonmethane hydrocarbons to 0.1 ppm. There are many commercially available
systems; however, simple designs can be obtained by using a series of
canisters.
From 40CFR Part 50 Appendix A-1 (this is not Part 58, Appendix A)
SO2
4.1.6.2 Clean zero air, free of contaminants that could cause a detectable
response or a change in sensitivity of the analyzer. Since ultraviolet
fluorescence analyzers may be sensitive to aromatic hydrocarbons and O2-toN2ratios, it is important that the clean zero air contains less than 0.1 ppm
aromatic hydrocarbons and O2and N2percentages approximately the same as
in ambient air. A procedure for generating zero air is given in reference 1.
What is Zero Air? (continued)
From 40CFR Part 50 Appendix C (this is not Part 58, Appendix A)
CO
3.2 Dilution gas (zero air). Air, free of contaminants which will cause a
detectable response on the CO analyzer. The zero air should contain <0.1 ppm
CO. A procedure for generating zero air is given in Reference 1.
From 40CFR Part 50 Appendix F (this is not Part 58, Appendix A)
NOx
1.3.2 Zero air. Air, free of contaminants which will cause a detectable response
on the NO/NOX/NO2analyzer or which might react with either NO, O3, or NO2in
the gas phase titration. A procedure for generating zero air is given in reference
13.
Commercial Zero Air Generator
Series of scrubbers
Desiccant, Purafil, Molecular sieve, activated carbon,
whatever scrubber media is needed
(supply a clean, cooled,
dry air flow source that
meets pressure needs –
always put a 0.1 micron
particulate filter
downstream of
scrubbers)
What are Gas Standards?
From QA-Handbook – Vol – II (Redbook):
12.1.2 Gaseous Standards
In general, ambient monitoring instruments should be calibrated by allowing the instrument to sample and
analyze test atmospheres of known concentrations of the appropriate pollutant in air. The following is an
excerpt from 50 CFR Part 58, Appendix A Section 2.6.1:
“Gaseous pollutant concentration standards (permeation devices or cylinders of compressed gas)
used to obtain test concentrations for carbon monoxide (CO), sulfur dioxide (SO2), nitrogen
oxide (NO), and nitrogen dioxide (NO2) must be traceable to either a National Institute of
Standards and Technology (NIST) Traceable Reference Material (NTRM) or a NIST-certified
Gas Manufacturer’s Internal Standard (GMIS), certified in accordance with one of the
procedures given in reference 4 of this appendix. Vendors advertising certification with the
procedures provided in reference 4 of this appendix and distributing gasses as ‘‘EPA Protocol
Gas’’ must participate in the EPA Protocol Gas Verification Program or not use ‘‘EPA’’ in any
form of advertising.”
"Traceable" is defined in 40 CFR Parts 50 and 58 as meaning that a local standard has been compared and
certified, either directly or via not more than one intermediate standard, to a primary standard such as a
National Institute of Standards and Technology Standard Reference Material (NIST SRM) or a
USEPA/NIST-approved Certified Reference Material (CRM)”.
In general, ambient monitoring instruments should be calibrated by allowing the instrument to sample and
analyze test atmospheres of known concentrations of the appropriate pollutant in air. The following is an
excerpt from 50 CFR Part 58, Appendix A Section 2.6.1:
“Gaseous pollutant concentration standards (permeation devices or cylinders of compressed gas)
used to obtain test concentrations for carbon monoxide (CO), sulfur dioxide (SO2), nitrogen
oxide (NO), and nitrogen dioxide (NO2) must be traceable to either a National Institute of
Standards and Technology (NIST) Traceable Reference Material (NTRM) or a NIST-certified
Gas Manufacturer’s Internal Standard (GMIS), certified in accordance with one of the
procedures given in reference 4 of this appendix. Vendors advertising certification with the
procedures provided in reference 4 of this appendix and distributing gasses as ‘‘EPA Protocol
Gas’’ must participate in the EPA Protocol Gas Verification Program or not use ‘‘EPA’’ in any
form of advertising.”
"Traceable" is defined in 40 CFR Parts 50 and 58 as meaning that a local standard has been compared and
certified, either directly or via not more than one intermediate standard, to a primary standard such as a
National Institute of Standards and Technology Standard Reference Material (NIST SRM) or a
USEPA/NIST-approved Certified Reference Material (CRM)”.
From 40CFR Part 50 Appendix A-1 (this is not Part 58, Appendix A)
4.1.6.1 SO2 gas concentration transfer standard having a certified SO2 concentration of not
less than 10 ppm, in N2, traceable to a NIST Standard Reference Material (SRM).
From 40CFR Part 50 Appendix C (this is not Part 58, Appendix A)
3.1 CO concentration standard(s). Cylinder(s) of CO in air containing appropriate
concentrations(s) of CO suitable for the selected operating range of the analyzer under
calibration; CO standards for the dilution method may be contained in a nitrogen matrix if
the zero air dilution ratio is not less than 100:1. The assay of the cylinder(s) must be
traceable either to a National Bureau of Standards (NBS) CO in air Standard Reference
Material (SRM) or to an NBS/EPA-approved commercially available Certified Reference
Material (CRM). CRM's are described in Reference 2, and a list of CRM sources is available
from the address shown for Reference 2. A recommended protocol for certifying CO gas
cylinders against either a CO SRM or a CRM is given in Reference 1. CO gas cylinders should
be recertified on a regular basis as determined by the local quality control program.
From 40CFR Part 50 Appendix F (this is not Part 58, Appendix A)
1.3.1 NO concentration standard. Gas cylinder standard containing 50 to 100 ppm NO
in N2with less than 1 ppm NO2. This standard must be traceable to a National Bureau
of Standards (NBS) NO in N2Standard Reference Material (SRM 1683 or SRM 1684), an
NBS NO2Standard Reference Material (SRM 1629), or an NBS/EPA-approved
commercially available Certified Reference Material (CRM).
Basically, if you purchase EPA Protocol Gas at the right concentrations things should
be good. BUT, there are factors and calculations that impact what concentration you
can get out of your gas calibrator. Let’s talk more about generating a test gas
atmosphere to better understand this.
Creating a Test Atmosphere
Basically, it’s mostly about mixing ratios.
2 parts
this
Cal
Gas
15
parts
this
Zero Air
Test Atmosphere
Concentration & Flow
Gas/Titration/ Ozone
Flow must be correct!
Flow
Concentration & Flow
Environics 6100 gas calibrator with 100 ml/min Mass flow Controller (MFC) for the calibration
gas and a 10 liter/min (10,000 ml/min) zero air flow.
Flow controller limits – not trusted below 10% of range
(10 ml/minute is the minimum allowable flow on the cal gas MFC – 8ml/min won’t work)
These flow controllers are calibrated at EPA Standard flow (25˚C at 760 mmHg)
Note: most of the gas in a calibration bottle is actually N2.
Gasses flow differently and calibrators sometimes ask what
the source gas is in order to make small adjustments to flow.
If the cal gas is 50 ppm NO and 50 ppm SO2, almost all the
gas in the bottle is actually the mostly inert carrier gas, N2.
In this case flow would be set for N2 and not SO2 or NO.
The concentrations entered for concentration calculations
would be NO and SO2.
NO2 is typically generated by reacting ozone with the nitrogen oxide gas (NO)
from a cal bottle in the calibrator. This is called Gas Phase Titration (GPT)
Step 1. How much total flow do I want?
I need enough flow for each analyzer and some excess to ensure outside
air won’t mix with my test atmosphere
Analyzer 1 draws 0.5 slpm – Analyzer 2 draws 0.6 slpm - analyzer 3 draws
1.0 slpm
0.5 + 0.6 + 1.0 = a total analyzer draw of 2.1 slpm - add excess
Let’s make total flow 3.1 slpm. 3.1 standard liters per minute is the same
as 3100 standard cubic centimeters per minute
(A rotameter in the vent line can assure excess flow – it will measure flow
and you just look – tap the floating ball to be sure it isn’t stuck)
Step 2 – Calculate from this formula
(Flow of cal gas) X [cal gas bottle concentration]
[concentration of gas out ] =
Flow of zero air + Flow of cal gas + other flows
(note: the denominator adds up to total flow)
What do we know? Say we want a cal gas out of .090 ppm; we can pick that and
“concentration of gas out” is then known. We decided we wanted a total flow of 3.1
slpm (3100 sccm) so we know the total of the denominator, total flow. We also know
the calibration gas concentration (you can read it from the cal bottle – let’s say it reads
50.1 ppm). What don’t we know? We need to know the flow of the cal gas. Think
algebra and solve for flow of cal gas in the numerator in sccm units. WATCH your units!
(Flow of cal gas) X (50.1 ppm)
0.090 ppm =
3100 sccm
(0.090 ppm) X (3100 sccm)
50.1 ppm
=
(Flow of cal gas)
=
5.569 sccm PROBLEM!!!!!!!!
We did the calculation right so what’s the problem?
Our 100 ml/min calibration gas mass flow controller in the 6100 isn’t accurate below
10% of their flow maximum - 10% of 100 is 10 and we ended up with 5.569. We need to
have a higher total flow, a smaller mass flow controller for the cal gas (a 50 sccm flow
controller would work in this instance) or a lower concentration cal gas. The easiest
might be to just increase total flow, but there are limits. It’s a balancing act between
total flows, cal gas concentrations and the flow limits of your calibrator mass flow
controllers. Let’s explore this further.
Let’s find out what the minimum total flow would need to be in order to keep the cal gas
flow at 10% of the 100 sccm mass flow controller. This time we’ll solve for total flow
(Flow of cal gas is 10 sccm) X (50.1 ppm)
0.090 ppm =
Total Flow
(10 sccm) X (50.1 ppm)
Total Flow
=
= 5567 sccm
0.090 ppm
I can adjust my gas calibrator for a total
flow of 5570 sccm instead of 3100
sccm and get .090 out; we will have
additional flow to vent
What is the lowest concentration we can get from a 50.1 ppm cal gas bottle
concentration with 10 liter zero air mass flow controller and a 100 sccm cal gas mass
flow controllers in a calibrator?
Lets only use 100% at the top end of the zero air mass flow controller, or 10000 sccm
(10 slpm) and the minimum flow of 10 sccm for the cal gas mass flow controller (10%
of 100 sccm).
(Flow of cal gas is 10 sccm) X (50.1 ppm)
Output ppm =
= .050 ppm
10010 for total flow
NOx Analyzer Theory of Operation:
Chemiluminescence
O3
Sample
gas w/NO
Light leaks can
impact measurement
PMTs are sensitive
and can be damaged
by light
Illustration is from Teledyne API 200E Operator’s manual
Illustration is from Teledyne API 200E Operator’s manual
NOx Cycle goes through converter
Dark Cycle
bypasses RX Cell
NO
NO
Sample Air
NOx = NO + NO2
NOx
NOx – NO = NO2
NO2
Only NO reacts
with ozone
MolyCon
Molybdenum Converter
NO2 Converter
NO2 converted to NO
Rx Cell
P
M
T
NO
Valves
NO
NO Cycle
E
x
c
e
s
s
NO Cycle passes sample air to reaction chamber
Ozone reacts with NO
Ozone generator
Only NO reacts – NO2 isn’t measured
NO2 is calculated: NOx – NO = NO2
Dry filtered air
hv in reaction cell is measured by PMT
O
z
o
n
e
Gas Phase Titration (GPT) – Creating a NO2 test atmosphere
CFR Title 40 Part 58 Appendix A
3.2.2.2 (a) NO2audit gas for chemiluminescence-type NO2analyzers must also
contain at least 0.08 ppm NO. NO concentrations substantially higher than 0.08
ppm, as may occur when using some gas phase titration (GPT) techniques, may
lead to evaluation errors in chemiluminescence analyzers due to inevitable minor
NO–NOXchannel imbalance. Such errors may be atypical of routine monitoring
errors to the extent that such NO concentrations exceed typical ambient NO
concentrations at the site. These errors may be minimized by modifying the GPT
technique to lower the NO concentrations remaining in the NO2audit gas to levels
closer to typical ambient NO concentrations at the site.
[This is in the Annual Performance Audit Section, but is relevant to GPT]
In the next slide, [Norem] should be at least .080 ppm,
but not be excessively higher than that
Gas Phase Titration (GPT)
NO2 actual
NO2 expected
= % NO2 Converted
Some Other Important CFR
Requirements
•
•
•
•
•
QMPs/QAPPs/SOPs a must
Independent quality management
Establishment of a Primary Quality Assurance Organization
Use of NIST Traceable Standards
Use of FRM/FEMs at the appropriate operating ranges and with
appropriate settings
– PART 53—Ambient Air Monitoring Reference and Equivalent Methods
• Siting, Probe placement & acceptable probe materials
– Appendix E to Part 58—Probe and Monitoring Path Siting Criteria for Ambient
Air Quality Monitoring
– Appendix D to Part 58—Network Design Criteria for Ambient Air Quality
Monitoring
• AQS submittal and annual data certification
– 58.15 Annual air monitoring data certification
– 58.16 Data submittal and archiving requirements
28
SO2 Validation Template continued
NO2 Validation Template continued
CO Validation Template continued