# Presentation: 313551

## Excel Spreadsheet Headings

-  ID (NIST Identifier)
-  Specie (Analyte)
-  Balance Gas
-  Nominal Concentration
-  Batch Size (Number of Cylinders)
-  Certification Date (Year and Month)
-  Certified value
-  Uncertainty
-  Factor (Bias between producer and NIST
-  results)

## Company Participation by Year

## Companies Participating in the Gas Mixture NTRM Program

- AGA
- Air Products
- Airgas
- ALAC
- BOC / Airco
- Matheson
- MG
- Praxair / Liquid Carbonic
- Scott
- Spectra

## Graph of Number of Gas Mixture NTRM Batches by Year

## NTRM Batches by Year

## NTRM Batches by Year

## NTRM Batches by Year

## NTRM Batches by Year

## NTRM Batches by Specie and Year

## NTRM Batches by Specie and Year

## NTRM Batches by Specie and Year

## NTRM Batches by Specie and Year

## Measurement of Bias

## Continuing Problems

- Straight thread valves
- NO mixtures for NO2
- Low NO mixtures
- NOx mixtures
- H2S mixtures
- Hydrocarbon mixtures
- Analyze BS using GC then homogeneity by GC or THCA
- Other hydrocarbons
- NIST Primary Standards
- Sufficient standards for producer work

## Standards for Producer Analysis

- SRMs
- In certification NTRMs
- PRMs from NMi
- GMIS
- 	If standards other than SRMs or NTRMs are used then information 	detailing their preparation and verification will have to be supplied

## NIST Gripes

- Analyses by Producers
- Many seem to be done in production facility rather than laboratory
- Some data resolution done to 1 part in 50 which is 2% whereas we would like to see work done to 0.2%
- Data reduction does not seem to be sufficiently reviewed
- Reports are boiler plate rather than specific
- Report contents could be improved
- Producer Scheduling; planning ahead and sticking to plan

## Producer Gripes

- Turnaround time
- Scheduling and sticking to schedule
- Cylinder return
- Conflict resolution

## Conflict Resolution

- Most of this results from disagreement between NIST and the producer on the analytical value of batch ie Factor “f” too large
- Past approach
- NIST would redo the analysis to double check their result
- This was frequently done at a later time because of slowness of NIST data evaluation
- NIST would inform Producer of problem only after 2nd analysis which could have been months after 1st analysis
- Current approach
- NIST reviews NIST data in real time
- Any re-analysis is done while instrumentation is still set up
- Producer is informed shortly after QA on NIST results
- If Producer works to resolve the problem then continues to work with them
- If Producer does not respond promptly then a report will be issued stating that the batch is not certified “at this time” but giving the Producer the option to resolve conflict and have the batch certified
- The cost of certification is charged by NIST regardless of outcome

## Some Rejected Batches

- NO at 100ppm for high NO2
- NO at 50ppm for degradation with high NO2
- SO2 at 50ppm for inhomogeneity
- NO at 20ppm and below for degradation
- To date the only batches of NTRMs that have not passed the re-certification tests have been low level NO
- CO at 10ppm
- Producer said 0.3% spread in batch
- NIST determined 3% spread
- NO submitted at 100ppm analyzed to be 500ppm
- Producer could not definitively explain

## Uncertainties

- What are the requirements for U’s for NTRMs and SRMs?
- Are there regulations?
- Are there EPA requirements?
- Are U’s at 0.5% relative needed?
- Are U’s at 1% relative sufficiently good?
- Where are U’s incorporated in calculations?