by anwar sutan - i-vigilant...by anwar sutan agenda • objectives • regulation requirements •...

Review of ISO10723 Performance Test Frequency

By Anwar Sutan

Agenda

• Objectives

• Regulation Requirements

• Issues in analyzer system

• ISO 10723 Intention and Practices

• Case Studies

• Alternative method

• ISO 10723 – other method comparison

• Summary

Objectives

• To discuss the possibility of reducing ISO 10723 Performance test freq

• To consider other “Health Checks” to catch in-year GC issues

REGULATORY REQUIREMENTS

Regulatory Requirements (EU ETS)

• The commission of the European communities decision 18/7/2007

• Commission Regulation 601/2012 on the monitoring and reporting of greenhouse gas emissions– It does not mention ISO 10723 anymore


• Regulation from 2007 is much more quoted in comparison to the regulation from 2012

• Or

• Wording validation is interpreted as ISO 10723 Performance Test


• Determination of Calculation Factors based on analyses:– Use of laboratories

– Use of online gas chromatograph

– Use of offline chromatograph

PrecedenceOperators who determine calculation factors using laboratories did not get any audit points


• When using laboratory for calculation factors determination:

– There is minimum frequency of analysis in terms of sampling plan


• Different frequency is allowed if:

– Based on historical data, any variation does not exceed 1/3 of the uncertainty value to which operator has to adhere to

– Using the required frequency would incur unreasonable cost

Regulatory Requirements (DECC Guideline)

• DECC Guideline Issue 9

– 7.5.8. DECC may require operators of relevant systems to quantify at regular intervals the linearity and repeatability of fiscal gas chromatographs

– 7.6. The gas chromatograph should be subject to a ‘health check’, the frequency of which may be determined on a ‘risk-based’ analysis. DECC may insist on ISO 10723 certification

– 7.5.9. Calibration gas should lie within linear response of the analyser

ISSUES IN ANALYSERSYSTEM

Issues in Analyzer System

Pressure Let Down System

Heavy end drop out

GC

Linearity and repeatability, leakage etc

Ca

l gas

Stratification / high uncertainty cal gas

Human Error / Procedure

Issue Sensitivity

Issue Errors found

Heavy end drop out in PLS More than £150K /month (0.8%)

Calibration gas error More than £50K /month (0.35%)

Human error More than £300K /month (1.4%)

Linearity from GC (Up to 20% difference in Methane) 0.075% in CV (Acceptable CV uncertainty of 0.2%)

Validation / Health Check

ISO 10723 INTENTION AND PRACTICES

ISO 10723 INTENTION

• To quantify GC repeatability

• To quantify GC linearity

• To determine GC Performance benchmark– Errors (bias)

– Uncertainties (from calibration gas and repeatability)

– Overall bias Combination of errors and uncertainty

• Overall to validate that GC is working correctly (Health Check)

• There is no calibration being done during this process

Current ISO 10723 Practices

• Many operators do it once a year / once every two years

• Range of gas is very often not as per actual concentration


• Linearization constants are seldom implemented (only 4 out of 30 GC on case study has multilevel calibration constant applied)

• Some GC don’t have these feature inside the GC


• The benchmark is only valid if the GC maintains performance characteristics measured on the day of calibration

• Many operators send a GC specialist prior to ISO 10723 test

• Extra cost

CASE STUDIES

Case study

• Two tracking GC of which one failed ISO 10723 test

• MLC constants applied vs single point calibration mole%

• Errors masked by polynomial curve

• ISO 10723 test – GCAS – ISO 10723 test

Case Study 1

• Performance test failed outside the actual gas range

Case Study 2

• MLC mole% vs single point calibration mole%

Case Study 2

• CV and Relative Density

Case Study 3

• ISO 10723 Performance check may be performed on Chromat with:

– Valve timing error

– Peak cuts

The benchmark is only valid if the GC maintains performance characteristics measured on the day of calibration

Case Study 3

• ISO10723 Polynomial constants are formed under faulty conditions

• Errors are masked by polynomial curve

Case Study 4

• ISO10723 – GCAS monitoring – ISO10723 was done

Case Study 4

• Could we reduce the ISO 10723 test frequency in this case?

WHAT IS THE ALTERNATIVE?

i-Vigilant’s GCAS Method

What is the method?

• Footprint and calibration data

Ascending trends and high correlation ensures correctness of calibration gas as well as events timing in GC

What is the method?

• Uncertainty monitoring

Uncertainty limit can be set to flag an alarm when limit is reached

What is the method?

• Last calibration data update monitoring

When data is not updated it’s an indication that GC calibration has failed

In a Nutshell

GCAS GC Validation

• Valve timing correctness

• Calibration gas correctness

GCAS GC Validation



• Control chart

GCAS GC Validation



• Control chart

• Uncertainty calculation

GCAS GC Validation



• Control chart


• Spot sampling checks

GCAS GC Validation



• Control chart


• Spot sampling checks

• Fully auditable comments

Issues in Analyzer System

Pressure Let Down System

GC

Ca

l ga

s

RISK BASED

Other Validation Method

• GC calculated density vs densitometer measured density

• GC calculated VOS vs USM measured VOS

ISO10723 vs GCAS

• The only health check / validation feature that’s missing in GCAS is linearity determination

• Density or VOS comparison is additional set of validation that can be used• ISO 10723 to determine GC linearity

CONCLUSION

Where the following conditions are met:– Initial ISO 10723 has been done on well maintained GC


– Actual measurement bias are within acceptable limit


– Actual measurement bias are within acceptable limit

– GC proves to be reproducible throughout the year (low uncertainty)

When Do We Need to do ISO10723 Performance Test?

• DECC Guideline: ‘risk-based’ analysis

• Error exposure if it’s not being done

• Arguably, ISO 10723 should be done any time there’s a major change in thermal conductivity property of detector

Considering all that

• Can the frequency of ISO 10723 be reduced?

• What would be the requirement to do that?

Thank [email protected]

i-Vigilant

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