EPA HCl Performance Specification 

Draft Conference Call Summary

Thursday July, 21 from 1:30-2:30 EDT.

Call in Conference Number 1-866-299-3188, code is 9195415511. 

Stakeholder Discussion Topic:

What are the best approaches for in the field QC/recovery checks. 

1) Welcome – Introduction

a) EPA plans to have stakeholder calls on various topics at a frequency of once every two weeks

b) We will work from the list of issues previously sent to the stakeholder. The specific topic from 

the list will be announced by email prior to the meeting to allow everyone to prepare. We will try 

to limit discussion to the announce topic so stakeholders can choose which conference calls to 

attend. We plan to cover all of the topics in our original summary and may add topics that arise 

from our ongoing discussions with stakeholders.

c) EPA will start working on a draft of the performance standard in August based in part on the 

information from the stakeholder calls. Over the next six weeks stakeholders (Table 1)

participating in this call will start seeing draft sections of the Performance specification and is 

associated procedure. Comments on the drafts are welcome so we can get your input well before 

we have a complete draft.

d) Our timing remains to have the first full draft for Stakeholder review by the end of the calendar 

year (2011).

2) Field QC Topics Discussion - In field hot wet through the probe spiking

When area source tests were performed for cement plants, Jim Peeler - Emissions Monitoring Inc. 

used Method 321Measurement of Gaseous Hydrogen Chloride Emissions At Portland Cement Kilns 

by Fourier Transform Infrared (FTIR) Spectroscopy. This method requires through the probe spikes, 

including specifications for the maximum amount of spike introduced through the probe, and the 

relative concentration of spike that can be used. This QC approach provides an evaluation of the 

measurement system since it demonstrates that you can successfully transport a known concentration 

of gaseous HCl through the probe and filter cake into the heated instrument cell. For cement kiln HCl 

measurement, the filtered particulate matter is comprised solids that react with HCl. Through the 

probe spiking provides an assessment of both the sampling/analysis system and it tests the 

mathematical algorithms used in some equipment to correct for interferences in the sample matrix. 

a) The spike is limited to a maximum of 10% of the sample gas stream. The concentration target for 

through the probe spiking is the approximate concentration of the gas stream or 5 ppm is the gas 

tested is less than 5 ppmv. For example, spiking a gas stream of 5 ppm involves using a certified 

gas at 50 ppmv HCl which is diluted 10/1 resulting in the addition of a spike of 5 ppm in addition 

to the stack gas HCl. The measured concentration of native plus spike is approximately double 

the concentration of the native HCl. In this approach the spike gas dilutes the native concentration 

by approximately 10%. 

b) The sample gas flow rate and the spike gas flow rate must be measured very accurately or the 

tester can inject a known concentration of tracer such as SF6 to determine the exact dilution.
c) The calibration gas standard is also delivered directly to the measurement device to determine 

response of the standard gas without sampling system or sample matrix bias. This QC check is 

the relative concentration or relative indicator used to determine spike recovery. Direct 

instrument measurement of the spike gas provides the exact response of the spike gas regardless 

of the absolute concentration of the certified gas cylinder.

d) Spike recovery can be determined in different ways as described in the ASTM FTIR 

measurement procedure for Stationary Sources. Recovery based requirements permit the 

measurement procedure to be performance based rather than the more restrictive performance 

requirements of a prescriptive procedure. 

i) Spike recovery can be based on the total expected response for the native plus the spike or

ii) Spike recovery can be based on the incremental response resulting from the spike addition to 

the native concentration.

e) For sources with highly variable HCl emissions there is a question of whether two analysis units 

are required so the instantaneous native HCl can be separated from the through the probe spike 

response. In both the ASTM procedure and Method 321, there are cautions about spiking when 

the process is not stable. One alternative useful for highly variable sources is calculating the 

average of native concentration just prior and just after the spike interval. Furthermore, if a the 

QC spike check fails and the tester believes the cause is temporal variation of the source, the 

spike can be repeated when the source is relatively constant. Since the measurements are 

continuous, a simple statistical test on process variability may be useful to identify when the 

measurements are out of control or the failure is due to process variability.

f) EPA has a guideline document for monitoring non-criteria pollutants that addresses these issues.

g) Allen Rilling - ABB: The spiking system through the probe identifies sampling system bias. 

What is the issue spiking at the analyzer once the initial performance of the system is verified. 

Jim Peeler: Through the probe spiking is valid for a period of time until the accumulation of 

material on the filter from the process biases the results. For cement kilns the filter collects 

calcium oxides and other material that reacts with HCl. Sulfur Oxides compete for adsorption 

sites on the filtered material so through the probe spiking needs to be done periodically to confirm 

the measurement system meets bias requirements. During measurement programs for HCl, 

testers are required to verify the instrument performance before and after each test run. The 

measurements requirement seems excessive for a continuous monitoring system but is standard 

for periodic measurement programs. However, periodic through the probe is necessary to 

determine when sufficient material was accumulated on the filter to significantly bias the 

monitoring results.

h) Robin Segall - EPA: suggests that if daily calibration checks are required as system calibration 

versus an analyzer calibration. A daily calibration check through the filter will provide 

information on the bias caused by the filtered solids as opposed to an instrument only calibration 

check that provides information on instrument drift and span. System calibration through the 

filter should be done daily but there’s not enough information on cement kiln continuous 

monitoring to evaluate how often the analyte spike should be performed. Lime plants, 

downstream of limestone scrubbers and cement kilns are probably the worst case examples for 

needing through the probe analyte spikes.

i) Jim Peeler: If daily system calibration checks are required then the job of the analyte spike 

technique performs is the same as the function of a RATA. That is to detect excessive sampling 
system bias and measurement interferences. Currently he does accuracy assessment on a 

quarterly basis. He suggests doing initial certification including a series of through the probe 

spikes during a seven day certification period and then quarterly thereafter. 

j) Robin Segall: Question, are you proposing to substitute analyte spiking for a RATA against a 

reference method? Jim Peeler: Yes, thus avoiding the issue of using reference Method 321 for 

HCl based on FTIR to evaluate an FTIR CEM. If a facility failed the quarterly through the probe 

analyte spike then there could be a requirement to do the spiking more frequently.

k) Jim Peeler: Agreed that calibration checks include the entire system for regulatory programs and 

the requirement in this PS should be consistent with that practice. If a system calibration check 

fails, testers would immediately run an analyzer calibration check to eliminate drift or response 

changes as the cause of the system calibration check failure.

l) Allen Rilling : shared his concern about the amount of gas required to perform system calibration 

checks through the probe. If quarterly checks verified no system bias, he asked if direct 

instrument calibration checks would be adequate.

m) Laura Kenner: For cement kilns, quarterly through the probe QC checks seem too infrequent. 

Allen Rilling: Once you’ve built up a history of passed QC checks, then less frequent through the 

probe QC checks seem to make sense and would reduce costs for calibration gas as well as 

increase uptime for source monitoring.

n) There was some discussion of needing to do a direct instrument and a system calibration check 

sequentially to ensure that changes in the calibration gas concentration did not bias the QC check. 

This assumes that the calibration is not stable and that issue will be discussed on a separate call.

o) Robin Segall: Using HCl CEMS in a compliance mode will require performing system 

calibration checks on a relatively consistent basis. The starting point would probably be a daily 

calibration check since EPA established this frequency for our other compliance programs. 

p) Allen Rilling: Once you have an analyzer that demonstrates unbiased measurement for a year 

then you have support for performing less frequent calibration checks. He asked if it was 

possible to base the frequency of system calibration checks on a past experience history for a 

specific monitor installation.

q) Robin Segall: If we wrote such a Performance Specification, the data from an interval between a 

failure and the previous passed system calibration check would be invalid data.

r) Jim Peeler: Appendix F invalidates data from the time a QC check or audit is failed forward and 

does not retroactively invalidate data because a source operator might be encourage to fail a test 

to invalidate data the facility did not “like”. For systems like FTIR that measure multicomponents, if the system is measuring one component correctly the instrument is probably 

measuring the other components that get to the analyzer correctly. That would mean a calibration 

check for one component would assure that the instrument was operating correctly for all 

components. The most reactive component being measured might serve as a surrogate for the rest 

of the multi-component measurements and that component will probably be HCl.

3) Alternatives to hot – wet – through the probe QC checks

a) Rich Brown – Altech: Is the performance specification we are discussing an update of the FTIR 

procedure or is it a general HCl monitoring performance specification? Candace Sorrell - EPA: 

The performance specification will be generally applicable to all technologies measuring HCl 

including all current HCl stack monitors and future technologies that serve this purpose. Altech 

uses Perma-Pure nafion dryer technology at the probe location followed by dry delivery to a 
multigas NDIR filter based monitor. This system is not hot wet since the sample is dried at the 

sampling probe/sampling location. Altech does not use an all heated system after the dryer. The 

system is an extractive system that brings dry cool sample to the analyzer. The stack gas hot (180 

C and filtered prior to the dryer. There is no issue with spiking in the hot wet zone in front of 

the filter. That means this sampling design would not be excluded from using a hot wet HCl 

performance spike. Jim Peeler: We’ve successfully performed hot, wet field spikes with HCl 

using the Altech system. 

b) Laura Kenner - Emission Monitoring Inc.: It seems that hot wet spiking should work for 

extractive systems. In-situ monitoring systems may require a different approach.

c) Keith Crab - Cemtech Environmental: Cemtech offers an in-situ tunable diode laser cross stack 

monitoring system. Cemtech uses a flow through cell in the optical measurement path that can be 

spiked with calibration gas to check instrument performance. The cell functions in a similar 

manner to the hot wet spike since it is an additive spike to the measurement path. The cell can be 

mounted on the stack or at the instrument. The flow through cell seems to be a valid test of the 

instrument performance that can be practically tested. Higher concentration gases appropriate to 

the path length would be required for flow through cell spiking. This technology lends itself to 

multipoint QC or calibration checks. At the end of a QC cycle the cell is flushed with nitrogen

until the baseline before spiking is reached. The cell remains in place during measurements and 

calibration checks. There is no practical way of doing a cross stack zero measurement insitu. 

Zero and span checks will be discussed in a separate stakeholder call. The temperature and 

pressure of the gas cell and the stack gas must be included in the calculation of gas concentration. 

Cemtech’s flow through cell is not heated and equilibrates to the temperature at its location. 

Lorentzian line shape is used in the calculation of concentration.

d) Cemtech is also investigating an extractive dynamic probe TDL system that could be spiked with 

HCl through the probe similar to other extractive systems.

4) Concentration of spikes

a) Jim Peeler: With emission standards approaching 3 ppm for cement kilns there are issues because 

plants that include inline raw mills will cycle between mill off high concentrations and mill on 

low concentrations. What’s the best concentration to spike and is it reasonable to assume that if 

spikes at low concentrations are recovered successfully then higher spike concentrations will also 

be recovered successfully? Periodic testing supports this conclusion.

b) Low concentration spikes are more a concern during calibration checks when 100 % gas 

(flooding the system with calibration gas) is being tested. Dynamic, hot wet spiking is not 

performed at no more than 10% of the volume of gas sampled which means the spike gas can be a 

higher concentration. The spike gas should not be the same gas as the calibration check standard 

gas. This hot wet dynamic spike is similar to quarterly cylinder gas audits used in other 

programs.

c) Luc Sevrette – Gasmet: Are we talking about a representative daily check, and if so a calibration 

check going through the system dry would take more than an hour to equilibrate. He 

recommends a daily hot wet spike through the probe but not a daily calibration check with low 

level standards that must equilibrate through the system dry.

d) Allen Rilling: We typically spike at 75% of the measure emission level. The new compliance 

limits present additional bias opportunities since the concentration is so low that the delivery 
systems may affect how accurately the HCl can be delivered to the probe. Options to consider are 

daily zero and span or daily through the probe spike. 

e) Also to be considered is the possibility of using a tracer gas to verify the dilution ratio of the 

spike gas delivery system in place of relying on mass flow controllers or rotameters for flow 

measurements. This may be an option for multi-component monitors but may be a issue for 

narrow wavelength or single component systems that only measure HCl. If the definition of 

tracer gas is left flexible, then manufacturers will have to solve this issue on an instrument 

specific basis.

Table 1: Conference Call Attendees and Contact Information

Stakeholder Name Affiliation Interest Email Present

Rachael Agnew EPA/OAQPS/SPPD/MPG EPA agnew.rachael@epa.gov

Joe Aldina Covanta Energy Facility jaldina@covantaenergy.com

Collin Boswell EPA/OAQPS/SPPD/MPG EPA boswell.collin @epa.gov

Rich Brown Altech Equip Vendor Y

Gary Catchatory Tyco Environmental Systems Equip Vendor

Kieth Crab Cemtech Environmental Equip Vendor Y

Edul Chikhliwala EcoChem Analytics Equip Vendor chikli@ecochem.biz

Michael Corvese Thermofisher Equip Vendor michael.corvese@thermofisher.com

Bob Davis AirGas Gas Vendor bob.davis@airgas.com

Jason Dewees EPA/OAQPS/AQAD/MTG EPA dewees.jason@ epa.gov

Frank Duckett Thermofisher Equip Vendor frank.duckett@thermofisher.com

Andy Edwards Ash Grove Cement Facility

Gerri Garwood EPA/OAQPS/SPPD/MPG EPA garwood.gerri@epa.gov

Fred Grunewald MKS Instruments Inc. Equip Vendor fred.grunewald@mksinst.com

Desirea Haggard Cal Portland Facility dhaggard@calportland.com Y

Jeff Harrington Tyco Environmental Systems Equip Vendor

Malik Hatar Altech Equip Vendor

Mike Hayes Linde Gas Gas Vendor

Andre Hegre Gas Technologies, Finland Equip Vendor

Stephen Johnson Thermofishter Inc. Equip Vendor Stephen.Johnson@thermosisher.com

Dan Kietzer Sick-Maihak Equip Vendor dan.kietzer@sickmaihak.com

Laura Kenner Emission Monitoring Inc. Tester lkinner@mindspring.com Y

Dieter Kita Thermofisher Equip Vendor dieter.kita@thermofisher.com

Bill McMaster PermaPure Equip Add-on Y

Barbara Marshick MKS Instruments Equip Vendor Barbara_Marshik@mksinst.com

Ray Merrill EPA/OAQPS/AQAD/MTG EPA merrill.raymond@epa.gov Y

Barrett Parker EPA/OAQPS/SPPD/MPG EPA parker.barrett@epa.gov

Ashmud Patel Ethyl Smith Automation

Jim Peeler Emission Monitoring Inc. Tester jimpeeler@mindspring.com Y

Allan Rilling ABB Equip Vendor allan.j.rilling@ca.abb.com Y

Ralph Roberson RMB Consulting Tester Roberson@mb-consulting.com

Matthew Rutledge Lafarge Facility

Robin Segall EPA/OAQPS/AQAD/MTG EPA segall.robin@@epa.gov

Luc Sevrette Gasmet Equip Vendor luc.sevrette@gasmet.com

Ty Smith Cemtech Environmental Equip Vendor

Candace Sorrell EPA/OAQPS/AQAD/MTG Regulatory 

Agency

sorrell.candace@epa.gov Y

Martin Spartz Prism Analytical technology Tester m.spartz@pati-air.com

Bob Vantuyl Ash Grove Cement Facility bob.vantuyl@ashgrove

Henry Veger CEM Specialties Equip Vendor

Dave Vigowax Marantee Tile Facility

Bethany White RMB Consulting Tester Y

James Willis Titan America Facility jwillis@titanamerica.com

Hector Ybanez, Holcim Inc. Facility hybanez@gmail.com

Musa Zada Altech Equip Vendor

Peter Zemek MKS Instruments Equip vendor Peter_Zemek@mksinst.com Y

Y= Higlighted attendance indicates first time participants.