Low 54.0 Pass FTIR GMIS 47.5 Pass FTIR GMIS 5.0 Pass FTIR GMIS

Mid 401 Pass FTIR GMIS 499 Pass FTIR GMIS 12 Pass FTIR GMIS

High 911 Pass FTIR GMIS 981 Pass FTIR GMIS 18 Fail Pass FTIR NTRM

Low 48.90 Fail Pass Chem NTRM 47.73 Pass NDIR NTRM 5.01 Pass NDIR NTRM

Mid 406.0 Pass Chem NTRM 496.8 Pass NDIR NTRM 12.0 Pass NDIR NTRM

High 900.0 Fail Pass Chem NTRM 994.6 Pass NDIR NTRM 18.0 Pass NDIR NTRM

Low 51.4 Pass NDIR NTRM 50.4 Pass NDIR GMIS 5.0 Pass NDIR NTRM

Mid 388 Pass NDIR NTRM 500 Pass NDIR NTRM 12 Pass NDIR NTRM

High 845 Fail Pass NDIR NTRM 1000 Pass NDIR NTRM 18 Pass NDIR NTRM

Low 50.05 Fail Pass Chem GMIS 50.23 Pass NDIR NTRM 5.04 Pass NDIR NTRM

Mid 397.5 Pass Chem NTRM 502.8 Pass NDIR NTRM 12.0 Pass NDIR NTRM

High 900.0 Pass Chem NTRM 998.8 Pass NDIR NTRM 18.1 Pass NDIR NTRM

Low 49.8 Pass FTIR SRM 50.9 Pass FTIR SRM 5.0 Pass FTIR NTRM

Mid 407.8 Fail Pass FTIR SRM 500.4 Pass FTIR NTRM 12.0 Pass FTIR NTRM

High 900 Fail Pass FTIR SRM 1000 Pass FTIR NTRM 18 Pass FTIR NTRM

Low 50.4 Pass Chem GMIS 48.7 Pass NDIR GMIS 5.2 Pass NDIR NTRM/GMIS

Mid 396 Pass Chem GMIS 466 Pass NDIR GMIS 13 Pass NDIR NTRM/GMIS

High 904 Pass Chem GMIS 956 Pass NDIR GMIS 18 Pass NDIR NTRM/GMIS

Low 48.9 Fail Pass FTIR SRM 49.5 Pass FTIR SRM 5.2 Fail Pass FTIR SRM

Mid 410 Fail Pass FTIR SRM 504 Pass FTIR SRM 12 Pass FTIR SRM

High 904 Pass FTIR SRM 988 Pass FTIR SRM 18 Pass FTIR SRM

Low 50.0 Pass Chem GMIS 50.1 Pass NDIR GMIS 5.1 Pass NDIR GMIS

Mid 398 Pass Chem GMIS 501 Pass NDIR GMIS 12 Pass NDIR GMIS

High 888 Pass Chem GMIS 1004 Pass NDIR GMIS 18 Pass NDIR GMIS

Low 50.0 Pass Chem GMIS 49.3 Pass NDIR GMIS 5.1 Pass NDIR GMIS

Mid 403 Pass Chem GMIS 496 Pass NDIR GMIS 12 Pass NDIR GMIS

High 894 Pass Chem GMIS 1004 Pass NDIR GMIS 18 Pass NDIR GMIS

Low 46.2 Fail Pass FTIR GMIS 51.8 Fail Pass FTIR GMIS 4.9 Pass FTIR GMIS

Mid 398 Pass FTIR GMIS 500 Pass FTIR GMIS 12 Pass FTIR GMIS

High 930 Pass FTIR GMIS 991 Pass FTIR GMIS 18 Fail Pass FTIR GMIS

Low 51.2 Pass Chem GMIS 50.0 Pass UV GMIS 5.0 Pass NDIR GMIS

Mid 406 Pass NDIR GMIS 509 Pass NDIR GMIS 12 Pass NDIR GMIS

High 914 Pass NDIR GMIS 999 Pass NDIR GMIS 18 Pass NDIR GMIS

Low 50.0 Pass FTIR NTRM 50.4 Pass FTIR NTRM 5.0 Pass FTIR NTRM

Mid 402 Pass FTIR NTRM 503 Pass FTIR NTRM 12 Pass FTIR NTRM

High 911 Pass FTIR NTRM 1011 Pass FTIR NTRM 18 Pass FTIR NTRM

Low 50.8 Pass Chem GMIS 50.9 Pass UV GMIS 5.1 Pass GC GMIS

Mid 397 Pass Chem GMIS 504 Pass UV GMIS 12 Pass GC GMIS

High 886 Pass Chem GMIS 997 Pass UV GMIS 18 Pass GC GMIS

Low 50.1 Pass Chem NTRM 50.2 Pass NDIR NTRM 5.0 Pass NDIR GMIS

Mid 405 Pass FTIR NTRM 495 Pass NDIR GMIS 12 Pass NDIR NTRM

High 923 Pass FTIR NTRM 988 Pass NDIR GMIS 18 Pass NDIR NTRM

Vendor 

Analytical 

Technique

Reference 

Standard

A gaseous component was said to fail only if all available analytical techniques used in the audit indicated a greater than a 2.0% difference from the cylinder tag value. Any accuracy assessment is an 

instantaneous snapshot of the process being measured. These results should not be regarded as a final statement concerning the accuracy of EPA Protocol Gases. They can be used as an indicator

EPA presents this information without assigning a rating to the gas vendors, for example, who is the best, who is approved, or is not approved.

of the current status of the accuracy of EPA Protocol Gases as a whole. However, individual results should not be taken as definitive indicators of the analytical capabilities of individual producers.

Reference 

Standard

Tag Value 

(ppm SO2)

Gas 

Conc. 

Level

Original 

Tag Value

Reanalyzed 

Value

Vendor 

Analytical 

Technique

Reference 

Standard

Audit Result Audit Result

Original 

Tag Value

Spectra Gases Inc.

Messer MG Industries 

(Spec Air Specialty 

Gas)

National Specialty 

Gases

Praxair

Scott Specialty Gases

Vendor 

Analytical 

Technique

Original 

Tag Value

Reanalyzed 

Value

Reanalyzed 

Value

Tag Value 

(% CO2)

Airgas South Specialty 

Gases

BOC Gases

AGA / Linde Gas Group

Matheson Tri-Gas

Messer MG Industries

Scott-Marrin In.

Air Liquide

Airgas Southwest 

Specialty Gases

Airgas NCN Specialty 

Gases

NO

Audit Result

Tag Value 

Gas Vendor (ppm NO)

SO2

EPA Protocol Gas Audit Results

Tri-Blend NO/SO2/CO2 Gases - Certified According to EPA Traceability Protocol

EPA Cylinder Gas Assays: April 2003 - February 2004

CO2