ESTABLISHING A GAS FLOW CALIBRATION LABORATORY17 September 2015

Deona Jonker / Mpilo Dlamini / Eddie Tarnow

REASON FOR PROJECT

PROGRAMME

• 09h30 Arrival, registration and tea/coffee

• 10h00 Presentation by NMISA

• 10h45 Open question and answer session/discussion

• 12h00 Close

BACKGROUND

• Facilities providing services in the ambient air monitoring area must be SANAS accredited

• Measurement and testing equipment must be calibrated –traceability to national or international standards

• NMISA Gas Flow laboratory currently only laboratory capable of providing calibration service in the field of gas flow measurements

• Many instruments (bubble flow meters) need to be calibrated annually

• Result - long lead times

• Solution – establishment of more SANAS accredited laboratories for gas flow calibrations

NMISA PROPOSAL

• PHASE 1

• Presentation by NMISA on technical requirements to establish a suitable gas flow calibration laboratory

• Objective – identify parties wishing to advance to phase 2

• PHASE 2

• NMISA to offer support on request

• Suitable laboratory standards and equipment procurement

• Calibration methods

• Uncertainty contributors and estimation

• Objective – parties to conduct an accurate cost analysis of business model for establishing a gas flow calibration laboratory

NMISA PROPOSAL (cont.)

• PHASE 3

• Laboratory have to be ISO/IEC 17025 accredited

• NMISA provide calibration service for calibration of laboratory standards and other equipment at normal fees

BUBBLE FLOW METER

• Gilian Gilibrator model – 98% of bubble flow meters calibrated by NMISA

• Gilibrator system consists of• Control unit base

• 3 x Wet cells

• Low flow cell – 1 to 250 ccm

• Standard flow cell – 20 ccm to 6 LPM

• High flow cell – 2 to 30 LPM

• Primary standard • Primary standard airflow measurement – volume divided by time

• Volume (V) – measured volume of space between two infrared sensors

• Time (t) – time needed for soap film to travel between two sensors

• Flow rate = volume per unit time (V/t)

• Accuracy specification – better than 1%

CALIBRATION OF BUBBLE FLOW METERS

• Step 1 – calibrate the bubble flow meter

• Step 2 – calculate the measurement uncertainty

• Step 3 – generate the calibration certificate

• Step 4 – calibration sticker on instrument

CALIBRATION OF BUBBLE FLOW METERS

(cont.)

• Equipment needed

• Gas medium

• Control the gas flow – mass flow controller

• Laboratory standard

• Better accuracy than unit under test

• Unit under test

• Soap solution suitable for bubble flow meter

• Suitable tubing

• Suitable fittings

• Laboratory/calibration environment – controlled environmental conditions

• SANAS regulatory document TR-12: temperature 23 °C ± 5 °C

CALIBRATION OF BUBBLE FLOW METERS

(cont.)

CALIBRATION OF BUBBLE FLOW METERS

(cont.)

11h32 11h36 AVERAGE CORRECTION STDEV ESDM ESDM (%)

1000.1 1000.1 1000.3 1000.5 1000.3 1000.3 1000.3 1000.6 1000.5 1000.5 1000.35000 0.171594 0.054263 0.005424

1169 1165 1165 1166 1165 1164 1165 1165 1165 1165 1165.40000 1.349897 0.426875 0.036629

20.24 20.29 20.24 20.26 20.26 20.26 20.29 20.29 20.29 20.29 20.271 0.021318 0.006741 0.033256

87.16 87.16 87.16 87.16 87.16 87.17 87.16 87.16 87.16 87.16 87.161 0.003162 0.001000 0.001147

200 200 200 0 0 0

1022.1433 1018.4723 1018.6458 1019.4507 1018.5764 1017.8188 1018.4723 1018.4723 1018.4723 1018.4723 1018.89963 -18.550 1.205334 0.381160 0.037409

11h42 11h45 AVERAGE CORRECTION STDEV ESDM ESDM (%)

2000.3 2000.6 2000.6 2000.7 2000.8 2000.9 2001.4 2001.6 2002.1 2001.8 2001.08000 0.601480 0.190205 0.009505

2307 2309 2305 2309 2307 2314 2316 2311 2313 2314 2310.50000 3.659083 1.157104 0.050080

20.32 20.32 20.32 20.32 20.35 20.35 20.35 20.35 20.35 20.35 20.338 0.015492 0.004899 0.024088

87.16 87.16 87.16 87.15 87.15 87.15 87.15 87.15 87.15 87.15 87.153 0.004830 0.001528 0.001753

200 200 200 0 0 0

2016.6312 2018.3794 2014.8829 2018.1479 2016.1937 2022.3113 2024.0592 2019.6895 2021.4374 2022.3113 2019.40436 -18.324 3.052406 0.965255 0.047799

Pressure regulator (kPa)

UUT reading STD (sccm)

Nominal flow rate (ml/min)

Bios pressure reading (kPa)

Nominal flow rate (ml/min) 2000

Time

Bios reading (ml/min)

UUT reading VOL (ccm)

1000

Time

Bios reading (ml/min)

Bios temp reading (°C)

Bios pressure reading (kPa)

Pressure regulator (kPa)

UUT reading STD (sccm)

UUT reading VOL (ccm)

Bios temp reading (°C)

MEASUREMENT UNCERTAINTY

• Possible sources of uncertainty

• Reference standard

• Resolution

• Repeatability

• Temperature

• Pressure

• Tube length

• Etc.

• Measurement uncertainty calculated according to GUM –Guide to the expression of uncertainty in measurement

CALIBRATION CERTIFICATE

• According to the requirements - paragraph 5.10 of ISO/IEC 17025:2005

• Applicable SANAS document: R-79

FINANCIAL IMPACT OF CALIBRATING BUBBLE

FLOW METERS

• NMISA will calibrate ± 50 bubble flow meters from April to December 2015

• NMISA calibration fee - R3550 per flow cell

• On 2016 waiting list - ± 30 clients (not only bubble flow meter calibrations)

• Bubble flow meters to be calibrated annually

• Time duration of calibrating a flow cell• ± 6 hours calibration time (full range calibration – ten points)

• ± 3 hours - uncertainty analysis; certificate time; job administration

CONSIDERATIONS IN ESTABLISHING A GAS

FLOW LABORATORY

• LABORATORY

• Laboratory space

• Decide on gas medium

• Reference standard traceable to national/international standards – better accuracy than unit under test

• Gas flow equipment necessary for calibrations – if applicable, calibrated

• Calibrated environmental monitoring equipment

• Tubing, fittings, tools etc

CONSIDERINTIONS IN ESTABLISHING A GAS

FLOW LABORATORY (cont.)

• PERSONNEL

• Understand the concept of calibration

• Understand the consequences of reporting measurement results – correctness of your measurement

• Understanding of gas flow theory

• Understanding measurement uncertainties

• Understand measurement set-up – factors influencing measurement accuracy/uncertainty

CONSIDERATIONS IN ESTABLISHING A GAS

FLOW LABORATORY (cont.)

• REQUIREMENTS FOR SANAS ACCREDITATION

• Quality system – ISO/IEC 17025:2005

• Technical signatory requirements

• Introduction to measurement course

• Method validation course

• ISO/IEC 17025 course

• Uncertainty of measurement course

• MetCert registration requirements

• Acquire calibration experience

• Demonstrate overall competency

SUMMARY

• NMISA can assist

• NMISA cannot be prescriptive or give a definite recipe/method

• Potential laboratory has to make its own decisions

• Appropriate technical equipment

• Appropriate technical method

• Appropriate business model

• Appropriate staff

• Appropriate market

• SANAS accreditation must be obtained

• MetCert registration to be obtained

• Shortcuts will have implications

THE END

•GOOD LUCK

•Who is still interested to proceed to phase 3??