Marine Fuel h2s Round Robin Research Report March 6th 2012

7/28/2019 Marine Fuel h2s Round Robin Research Report March 6th 2012

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This document supports an Energy Institute Standard. It is a record of the round robin

study from which the precision of the test method was derived. It is available on requestfor study, however if the information in this document is intended to be used as part of anew document or presentation, the approval of the Test Method StandardizationCommittee Secretariat of the Energy Institute is required.

Marine Residual & Distillate Fuels

Research Report IP 570

(Procedure A)

Determination of Hydrogen Sulfide in Fuel Oils RapidLiquid Phase Extraction Method

SC-G-5

Author: Ian Mylrea, Chair EI SC-G-5 H2S Task Group

Dated 6th March 2012


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Round Robin Study Report Summary

A round robin was held using eight H2S Analyser Instruments and twelve samples in duplicate,to produce the repeatability and reproducibility of the test method. The samples used were

distillate and residual fuel oils and components. Values of measured H2S concentration variedfrom 0 to 12.5 mg/kg.

The resulting calculated expressions of repeatability and reproducibility (valid from 0.60 to 12.5

mg/kg) were as follows:

Range of Results (mg/kg) Repeatability (mg/kg) Reproducibility (mg/kg)

0 12.5 0.3329 x0.55 (65) 0.4459 x0.55 (95)

The round robin results have shown that IP 570 is suitable for measuring very low levels of H2Sdown to 0.6 mg/kg in the liquid phase. It is therefore recommended that the method be balloted

with the inclusion of this new precision for approval with this Research Report.

Introduction

Energy Institute Test Method IP 570 was developed in response to demand from industry for a

quick and reliable test to determine the level of hydrogen sulfide present in the liquid phase in

fuel oils.

IP 570 was first published in 2009 following an Energy Institute Round Robin in March 2009.Distillate fuels were omitted from the round robin due to there not being any suitable test

specimens with H2S present. Although it is unusual to get H2S in distillate fuels it is notunprecedented and occurrences have been reported. In 2011 a distillate round robin was

successfully completed and IP 570 was updated to include residual and distillate marine fuels.

Also in 2011 Note 5 was added to the method regarding interferences, which can cause

elevated readings. Further development of the method was required to remove interferences.

This round robin included a new procedure and equipment to remove interferences.

The information contained herein represents the finding of an Energy Institute round robin heldat the Stanhope-Seta Laboratory, Chertsey, UK, on the 14 th and 15th February, 2012. The trial

compared the performance of 8 instruments testing 12 samples in duplicate and in a random

order. In total 8 operators took part and a number of independent observers were present.

The purpose of the round robin was to update the current test method IP 570 Determination ofhydrogen sulfide in fuel oils Rapid liquid phase extraction method to include precision for the

new procedure and equipment using the new vapour phase process outlined.

Objectives

The objective of the study was to generate repeatability and reproducibility data for the test

method, to give an estimate of the performance of the instrument under typical laboratory

conditions for Marine Fuels as per ISO 8217.

Test Method

The test method used for this study was titled IP 570/12a draft Determination of hydrogen

sulfide in fuel oils Rapid liquid phase extraction method and is attached as Appendix B.


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List of Participating Laboratories and Operators

Owing to the unstable nature of H2S in marine fuels, all testing was done at a single site in twodays. The laboratory used in this study was at Stanhope Seta , London Street, Chertsey,

Surrey, KT16 8AP, UK. . The following people took part in the round robin.

Name CompanyAnne Christine Barbier Total (France)David Browbank Lintec

Gary Ogborn ITS (West Thurrock)Anna Prendergast. ITS (West Thurrock)Willie Schermer ShellBert Decelle ExxonMobilSimon Crozier NalcoPhil Mortimore ExxonMobil

The following people were independent observers at the round robin. Comments received can

be found in Appendix D.

Name CompanyVictoria Dodd UK Energy InstituteJim Barker Innospec (TMS SC-G Chair)Alister Jackson ExxonMobilDav Basra ConocoPhillipsBarbara Heyberger Total (France)


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Table 1 above describes the samples used in the round robin. All the samples except sample 9

and 11 were received directly from refiners. Sample 9 was sampled from a vessel. Sample 11

was purged with Hydrogen Sulfide.

In order to minimise the possibility of the concentration of H2S altering significantly over the testperiod, the samples were divided up into four groups to ensure that the duplicate test result was

obtained within a maximum of 4 hours of the first test result. Over two days there were fourgroups. Group 1 consisting of samples 1,2 and 3 were tested on the morning of Day 1. The

duplicate (repeat) was also in a random order and did not necessarily follow the first sample.

Group 2 consisting of samples 4,5 and 6 were tested on the afternoon of Day 1. Group 3

consisting of samples 7,8,9 and 10 were tested on the morning of Day 2. Group 4 consisting ofsamples 11 and 12 were tested on the afternoon of Day 2. No samples were tested on more

than one day and no samples were tested in the morning and afternoon.

Round Robin Protocol

The protocol was approved at the Task Group meeting January 13 th 2012. The table of sampleswas updated to include the actual samples used on the day. See Appendix A.

Apparatus

Eight H2S Analyser Instruments were used for the round robin testing. Each analyser alsoincluded a Vapour Phase Processor (VPP) as a permanent feature. As part of the instrument

apparatus, 10ml disposable syringes with a short length of 6mm nylon tubing and glass test

chambers were supplied. Syringes were used for taking the test portion . The size of the test

portion taken was 2ml or 5ml depending on the H2S concentration. VPP Cartridges (sorbent

specification SA4017/A), lot number 0001447701 were supplied. One cartridge was used for

each test. The manufacturer quality controls the cartridges. A new syringe was used to draw the

sample for each test.Software

The H2S Analysers all utilised software versions 5.00/2.00.

The VPPs all utilised software version 1.11.


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The test methodology requires the user to predict the H2S level prior to test and then choose the

appropriate volume of sample. As the samples were pre-tested advice was given on the volume

of sample to use in the protocol. In the case of Sample 2, which had an expected level of H2S of

just over 10 mg/kg it was advised to use a 2 ml test portion. However most results were < 10mg/kg and hence the wrong test portion volume was used. Sample 2 was therefore eliminated. .

Under normal laboratory conditions the sample test would have been repeated immediately,however in these cases this was not done. Future protocols shall include advice regarding this

aspect.

A long delay in starting the test was recorded against one of the test results, whereby the

sample had been kept at an elevated temperature for a long period. The test method does notcurrently include any advice, but it is good practice to introduce the test portion into the

apparatus just before commencing the test procedure to save degradation of the sample. It issuggested that an advisory note be added to the test method once the sample is in the test

chamber start the measurement without delay to avoid possible sample degradation. This could

be added under 11.4.8.The graphical outputs of three samples were checked in order to understand why the result waslower than expected. Upon inspection it was obvious that the graph was not shaped correctly

and typical of a change in flow rate during the test or for the entire test. It is suggested that a

typical graphical output is included in an appendix at the back of the test method to assist users.

It is not fully understood why this occurred and there is an investigation taking place by the

manufacturer into possible causes.

During one test the operator had reported that the apparatus baseline/background was

observed as changing from normal. Inspection of the data confirmed this. It is not fullyunderstood why this occurred and there is an investigation taking place by the manufacturer into

possible causes.

On one sample the operator reported bubbling/disturbing when injecting the sample into the test

vessel. This means that air in the syringe passed through the sample while it was added to thetest vessel. This practice results in a loss of H2S. See 11.4.4 in the test method do not expel

air from the syringe or pipette into the sample. A re-test was not done by the operator.


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Statistical Evaluation on the Data

The data was analysed according to ISO 4259 (IP 367) using the ASTM D2PP softwarepackage to generate values for repeatability and reproducibility. This analysis highlighted that,

as previously found in IP570 precision studies, there was evidence of excessive variabilityaccording to the concept of Limit of Quantitation. This implies that differentiation between

samples may be difficult at low levels of result (sample means below 0.6 mg/kg)

The data in Table 2 was analysed according to ISO 4259 (IP 367) using the D2PP software

package to generate values for repeatability and reproducibility. Full details of data used and theD2PP report can be found in Appendix C.

The repeatability and reproducibility were found to be:

Range of Results (mg/kg) Repeatability (mg/kg) Reproducibility (mg/kg)

0 12.5 0.3329 x0.55 (65) 0.4459 x0.55 (95)

These relationships are summarised in Table 3 and Figure 1:

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! ! !$"TABLE 3

%!&'%()(


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Thanks and acknowledgements

Members of the Working Group and to the participants and observers of the round robin

Royal Navy, ExxonMobil, Intertek, Total, ConocoPhillips, Chevron, Valero and Ineos for

supplying the test samples

Particular thanks to Stanhope Seta for the very generous use of their facilities


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Appendix A

This document supports an Energy Institute Standard. It shall not be reproduced or circulated or quoted, in whole or inpart, outside of the activities of the Standardization (SC) Committee of the Energy Institute except with the approval of the

chairperson of the SC Committee.

ROUND ROBIN STUDY IP 570

Determination of hydrogen sulfide in fuel oils

Rapid liquid phase extraction method

14th & 15th February, 2012

SC-G-5 Task Group on Measurement of H2S in the Liquid Phase


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Ian Mylrea

Task Group Chair

Stanhope-Seta

ISSUE 1.5

Dear EI TMS G-5 Panel H2S Task Group member,

As I am sure you aware that all our EI Panel activity in the EI TMS committees andpanels is carried out on the understanding that the meetings discussions and shareddocuments are for Panel use only and are not to be shared outside that EI Panelmembership, with the exception that within your organisation technical additional inputcan be shared/ supplied to enhance the method development.


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Please observe this protocol of maintaining the activity/discussions involving EIInterlaboratory Studies (i.e. Robustness Studies & Round Robins), anydata/observations derived from these studies are also deemed to be only for discussionwithin the EI Panel group activity (our Task Group), until the final agreement and

release of any Official EI TMS Panel reports that have been approved by the EI PanelMembership, EI Subcommittee Chair and EI TMS for public release and discussion.


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1 SUMMARY

The objective of this round robin study is to determine the precision of the test method in

accordance with ISO4259.

The successful outcome will result in the current test method IP 570 Determination of hydrogen

sulphide in fuel oils Rapid liquid phase extraction method being balloted to add precision for

distillate and residual fuels using the new Vapour phase process methodology outlined.

The study will be carried out at the SA Laboratory in Chertsey, on 14th & 15th February 2012

using 8 production instruments and the same number of operators plus observers nominated bythe Task Group members. 8 to 12 samples will be tested in duplicate and the EI statistician will

determine the repeatability and reproducibility.

2 INTRODUCTION

Energy Institute Test Method, IP 570, is already used by industry to measure residual marinefuels, for which precision data was obtained in 2009. A second round robin in 2011 added

precision for marine distillate fuels. The latest published version of the method is IP 570:2012. In

October 2010, at the H2S Task Group Workshop, held at the Lloyds registry, information

concerning interferences was submitted. Following studies by the manufacturer, a note (Note 5)

was added to the test method regarding the possibility of interfering chemicals such as low

boiling point thiols and alkyl sulfides elevating the readings. Research followed and a new

process was developed and tested with a wide range of samples and interferences. The new

process can be fitted, as an accessory, to the existing analyser.

ISO 8217:2010 requires the liquid phase Hydrogen Sulphide level to be determined according to

this method. There is a phased entry for this part of the specification to enable industry toprepare itself for the limit of 2 mg/kg. The limit comes into force in July 2012.

8 production instruments, fitted with the vapour phase process accessory are being used for this

round robin study.


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The test requires a weighed 1 ml to 5 ml sample, depending on H2S concentration, and tests are

completed in 15 to 25 minutes.

The development would not have been possible without the encouragement and support of

Lloyd's Register Group FOBAS Service, Intertek OCA and major refiners.

The SC-G-5 Task Group on Measurement of H2S in the Liquid Phase met at the EI and agreed

on the draft test method being used for this study.

3 TEST METHOD (attached)

Determination of hydrogen sulfide in fuel oils Rapid liquid phase extraction method


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4 SAMPLES

There are 12 samples as detailed below. Samples were typically supplied in 5 litre epoxy lined

containers, approximately 95% full. Distillate samples were supplied in 1 litre containers.

Reference Sample ID Type Nominal H2S

(mg/kg)

Test volume

req. (5ml)

SA0718 1 Distillate 3 to 6 5

SA0722 2 Decant Oil 10 to 12 2 (Two)

SA0701 3 Residual Fuel 0 to 3 5




SA0704 7 Bottoms 5 to 8 5


SA0707 9 F76 marine

distillate

0 to 3 5


SA0736 11 F76 marine

distillate

10 to 12 2 (Two)

SA0439 12 DMA 0 to 2 5

The above table outlines the desired range of H2S levels for this round robin. This is for

information only, as the actual H2S concentrations will depend on the samples available for the

testing on the day of the study.

5 PROTOCOLS INSTRUCTIONS FOR PARTICIPANTS

5.1 Each operator will be designated an individual apparatus and printer, and be given a copy of

the test method and this protocol.


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5.2 Operators will be given training before the tests commence.

5.3 Due to the volatility of the H2S and the need to test the potential of the apparatus and notthe sampling, samples are generally provided in 5L epoxy lined containers (except Sample 9, 10

and 11, which are supplied in 1 litre containers). For each sample there are 2 containers (exceptSample 10 & 11). 1 container enabled pre-testing of the sample to ensure the desired range of

H2S in the samples to be covered. The second container will be used by the participants for thefirst and duplicate test. Samples are supplied with minimum headspace from major refiners.

5.4 The sequence of testing will be in a random order and different for each operator.

5.5 Each operator will be given a results sheet that gives the required sequence of testing.

5.6 Testing should be in accordance with the test method, with these following points being ofparticular importance:

5.6.1 In order to minimise loss of H2S, do not homogenize or shake the sample before taking a

test portion.

5.6.2 Once a sample has been taken, immediately tightly replace the container seal to preventthe release of further H2S.

5.6.3 The correct size of sample can be determined by reference to table 1 below:

Table 1: Appropriate Test Volume for Expected H2S Concentration

Expected H2S Concentration Required Test Volume

0 - 10 mg/kg 5 ml

10 - 20 mg/kg 2 ml

20 mg/kg + 1 ml

5.6.4 Ensure that the Input sample weight in grams screen is displayed before removing the

sample vessel cap and introducing the test portion.

5.6.5 When introducing the sample into the test vessel, it is recommended that the operator lift

the test vessel proud of the surface. This enables the level of the liquid to be seen which helpsprevent the tip of the pipette or syringe touching the diluent oil.


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5.6.6 Pipette or syringe the test portion into the test vessel ensuring that the pipette or syringe is

held vertically to avoid sample adhering to the test vessel walls.

5.6.7 Once the sample has been entered into the equipment or vessel glassware, immediately

refit the glassware screw cap tightly to prevent leakage.


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Summary Guide to follow and run samples

1. Initiate cooling on the vapour phase processor (VPP)2. Insert a new cartridge into the VPP and replace the lid3. Allow 10 minutes before starting the test (Step 10 onwards)4. Using a 20ml syringe put 20ml diluent oil into a clean test vessel5. Place the vessel in the apparatus6. Set the mode of the apparatus to enable bubbling7. Wait for 5 minutes to allow diluent to warm up before obtaining the sample8. Type in the Sample ID9. Type in the Operator ID10. Go to the Samples.

a. choose the correct sample can from your test sheet.b. Obtain the sample using a clean 10ml syringec. Draw the sample into the syringe slowly and carefully to avoid exposing the

sample to a strong vacuum.

d. Take 10 to 20 seconds to draw the sample in for example. Draw the samplebeyond the 5ml mark.

e. Make sure the syringe is at least 3cm below the liquid surface of the samplecontainer

f. Avoid drawing air through the sample during sampling.g. Wipe the syringe with paper towelh. Add a tube to the syringe to facilitate correct application of the sample later on (it

may be convenient to add the tube before drawing the sample)11. Go to the weighing balance

a. weigh the syringe and tube and write down the Time in the Time column and theweight in the Full Syringe Weight column

12. Go to the apparatus.

a. select the mode of the apparatus to enter the weightb. enter the weight of the sample syringe.c. check the weight is correct.d. press the enter button.e. open the red cap of the sample vessel and inject the samplef. replace the cap immediately

13. Go to the SAME weighing balancea. weigh the syringe and tube and write down the weight in the Empty Syringe

Weight column14. Go to the apparatus

a. Enter the empty syringe weight, press return/enter.b. The VPP display should say ready to test

c. Once the apparatus is ready press Start15. The test is now under way16. DO NOT TOUCH the apparatus/ test vessel etc while a test is running17. Get the next sample test vessel ready by putting diluent in go to step 118. When the result appears write it down in the column for H2S


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6 APPARATUS

The apparatus to be used for the robustness study will be:

No Instrument H2S Serial

No

Software

Issue

STANHOPE-SETA H2S Analyser SA 4000-0 1022108 5.00

2 STANHOPE-SETA H2S Analyser SA 4000-0 1022109 5.00







No Instrument VPP Serial

No

Software

Issue

STANHOPE-SETA VPP 1022205 1.11

2 STANHOPE-SETA VPP 1022206 1.11







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7 EXAMPLE RESULTS PROFORMA


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Appendix B

IP 570/12A - draft

Determination of hydrogen sulfide in fuel oils Rapid

liquid phase extraction method

1 Scope

This document specifies a procedure for the determination of the hydrogen sulfide (H2S) content of fuel

oils such as marine residual fuels and blend stocks, in the range ( to be advised) mg/kg with viscosities

up to (to be advised) mm2s

1at 50C, and marine distillate fuels in the range (to be advised) mg/kg as

measured in the liquid phase. The method covers 2 procedures and relevant equipment.

NOTE 1 - By using a smaller volume of sample taken by a suitable positive displacement pipette, it is possible to

extend the range of the instrument to over 200 mg/kg.

NOTE 2 - The precision of this method is critically dependent on the sampling, thermal history and handling of thetest sample.

NOTE 3 - This standard is suitable for materials with a viscosity of over 3 000 mm2s

1at 50C, (see 7.2.1), but the

precision could be affected.

NOTE 4 - For the purposes of this standard, the terms "% ( m/m)" and "% (V/V)" are used to represent respectively

the mass fraction and the volume fraction.

NOTE 5 - Some samples can give elevated hydrogen sulfide readings if they contain thiols or alkyl sulfides above a

liquid phase concentration of approximately 5 mg/kg. Elevated readings, as mentioned, are avoided by following

Procedure A

WARNING 1 H2S is a very dangerous, toxic, explosive, colourless and transparent gas which can


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be found in crude oil. It can be formed during the manufacture of the fuel at the refinery and canbe released during handling, storage and distribution. At very low concentrations the gas has thecharacteristic smell of rotten eggs. However, at higher concentrations it causes a loss of smell,

headaches and dizziness, and at very high concentrations can be fatal. It is stronglyrecommended that personnel involved in the testing for H2S are aware of the hazards of vapour-phase H2S and have in place appropriate processes and procedures to manage the risk of

exposure.

WARNING 2 The use of this standard may involve hazardous materials, operations andequipment. This standard does not purport to address all of the safety problems associated withits use. It is the responsibility of the user of this standard to establish appropriate safety andhealth practices and

determine the applicability of regulatory limitations prior to use.

2 Normative references

The following referenced documents are indispensable for the application of this document. For dated

references, only the edition cited applies. For undated references, the latest edition of the referenceddocument (including any amendments) applies.

IP 475, Petroleum liquids Manual sampling (EN ISO 3170)

ISO TR 13739, Petroleum Products Procedures for the transfer of bunker fuel(s) to ships

3 Principle

A weighed test portion is introduced into a heated test vessel containing diluent base oil. Air is bubbled

through the oil to extract the H2S gas. The H2S is passed, with the air, via a filter cartridge which is held at

-20oC (Procedure A only) to a detector to enable the H2S content of the air to be measured and the

amount of H2S in the liquid phase to be calculated. In the case of Procedure B the filter cartridge isomitted.

4 Reagents and materials

Use only reagents of recognised analytical grade.


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4.1 Diluent oil1, proprietary water white API Group 2 base oil with a typical viscosity of 100 mm2/s at

40C.

4.2 Verification materials1, pressurized nitrogen, of at least 99,999 % (V/V) purity, containingcertified levels of H2S.

4.3 Toluene, technical grade.

4.4 Petroleum ether (60/80), technical grade.

4.5 Acetone, technical grade.

4.6 Filter cartridge, see Figure A.4, individually packed in a sealed envelope

5 Apparatus

5.1 General

The apparatus, as detailed in Annex A, comprises an air pump, test vessel, heating jacket, filters, H2Sspecific detector, integral computer, automatic solenoid valves, gas flow detectors, a disposable syringe.and (Procedure A only) a vapour phase processor.

5.2 Analytical balance, single pan or double pan balance capable of weighing to the nearest 0,001g.

5.3 Syringe, 20 ml polypropylene disposable type, for introduction of the diluent oil (4.1), accuracy 1%.

5.4 Pipette, 1 ml positive displacement pipette, for the introduction of the test portion. The accuracy

as stated by the manufacturer should be typically 0,25 % at 1 000 ml, with a coefficient of variation of

0,04 %. It is recommended that the syringe be of the same type as specified by the equipment

1A list of suppliers is available from the Energy Institute.


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manufacturer for optimum system performance.

5.5 Disposable syringe, 5 ml, or 10 ml, for the introduction of the test portion. Typical accuracy

1%. This may be fitted with a needle or extra tube to allow sample to be taken from 3 cm below the

surface, if appropriate.

5.6 Refrigerator (optional), for storing the test sample (see 6.4). The refrigerator shall be of a typesuitable for storing volatile materials.

5.7 Oven/water bath (optional), for warming the sample to 40C with an accuracy of 2C (see7.2.1). The oven shall be of a type suitable for use with volatile materials.

5.8 Ultrasonic bath (optional), general purpose for cleaning the test vessel (note under clause11.3).

6 Sampling and sample handling

6.1 Unless otherwise specified, samples shall be taken as described in IP 475.

Care shall be taken to ensure that the integrity of the material is maintained and the possible loss of H2Sis kept to a minimum. Where samples are drawn in a manner which does not minimise vapour loss (e.g.continuous drip sampling), dedicated samples for H2S determination shall be drawn.

6.2 Draw the sample directly into a suitable clean H2S inert container, of a minimum volume of 500ml. The closure aperture shall allow the drawing of a test portion with the pipette (5.4) or syringe (5.5). To

ensure sample integrity fill the sample container to approximately 95 % full and replace the capimmediately and securely.

NOTE 1 - It is recommended that containers such as dark brown borosilicate bottles or epoxy linedcontainers fitted with impervious gas-tight closures are used.

NOTE 2 - Lower volume containers may be used, however the precision could be affected.

NOTE 3 - In certain sampling situations it is impossible to draw samples directly into the sample container

owing to the equipment that must be used, for example, devices used to take samples through the roof of


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8.2 Location of apparatus

Use the apparatus under a suitable fume hood and vent the gas exit tube to a suitable extractor as the

test will release small amounts of H2S gas during test portion introduction and during the measurement.

8.3 Filters

8.3.1 The inlet air filter shall be replaced every 3 months or if any discolouration is visible.

8.3.2 Follow the manufacturers instructions regarding the replacement intervals of the air pump and

moisture filters.

8.3.3 Replace the moisture filter if any discolouration is visible.

9 Verification

9.1 Air flow rate

Verify that the air flow rate is 375 ml/min 55 ml/min at least once a year using a calibrated flow meter

connected to the air output connection. If the flow rate is incorrect, recalibrate the flow (10.1).

9.2 Test vessel heater

Verify that the temperature of the heater is 60,0C 1,0C at least every 6 months, by inserting a

calibrated platinum resistance thermometer into the heater. If the temperature is incorrect, recalibrate theheater temperature (10.2).

9.3 Validation of H2S detector

Follow the manufacturers instructions to verify the performance of the detector at least every month or

when a new detector is fitted at zero using air, and at a nominal 25ppm vapor concentration


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level using pressurized nitrogen (4.2) containing certified levels of H2S. If the measurement is not within

10 % of the certified value, replace the moisture filter and check the cleanliness of the liquid trap, test

vessel and associated tubing. Purge the system with air for30 min and attempt the verification again. If

the measurement is still outside the allowed tolerance, the detector needs recalibration or replacing. This

verification is to be undertaken at ambient temperature.

9.4 Validate the temperature of the vapour phase processor (Procedure A only)

Verify that the temperature of the cooler is -20,0C 2,0C at least every 6 months, by inserting a

calibrated platinum resistance thermometer into the cooler. If the temperature is incorrect, follow themanufacturers advice

10 Calibration

10.1 Air flow rate

Follow the manufacturers instructions to calibrate the air flow rate.

10.2 Test vessel heater

Follow the manufacturers instructions to calibrate the heater temperature.

10.3 H2S detector calibration

The detector is factory calibrated to allow for both the static and dynamic response to H2S. This

calibration information is held digitally on the detector assembly and is read directly by the computer in

the apparatus. The calibration enables results in mg/kg to be calculated from the test results.

Follow the manufacturers instructions for installing a new detector and verify the performance

immediately afterwards (9.3).

11 Procedures A & B

11.1 General


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It is recommended that Procedure A is used to determine the liquid phase Hydrogen Sulfide

concentration. Test results obtained using Procedure B may be elevated by the presence of Thiols

(Mercaptans) or alkyl Sulphides.

11.2 Procedure A

11.2.1 On switch on, the H2S apparatus shall control the test vessel heater to 60,0C 1,0C and purgeby pumping air directly to the detector.

11.2.2 Clean the test vessel and screw cap before each test. The test vessel shall be clean and drybefore use. Fit the screw cap tightly.

11.2.3 Empty and clean the liquid trap if any liquid or discolouration is visible.

NOTE - Toluene (4.3) followed by petroleum ether (60/80) (4.4) and acetone (4.5), in conjunction with an ultrasonic

bath (5.8) have been shown to be effective in cleaning the test vessel, cap, and liquid trap.

11.2.4 Insert a filter cartridge (4.6) into vapour phase processor, following manufacturers instructions

11.2.5 Initiate cooling on vapour phase processor, allow at least 10 minutes before proceeding with step

11.4.

Note an interlock between the analyser and vapour phase processor prevents the sample weight beingentered before the filter cartridge has been cooled and is ready to test

11.2.6 Ensure the vapour phase processor has completed its cool down cycle before introducing thesample

11.3 Procedure B

11.3.1 Upon switch on, the H2S apparatus shall control the test vessel heater to 60,0C 1,0C andpurge by pumping air directly to the detector.

11.3.2 Clean the test vessel and screw cap before each test. The test vessel shall be clean and dry


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before use. Fit the screw cap tightly.

11.3.3 Empty and clean the liquid trap if any liquid or discolouration is visible.

NOTE - Toluene (4.3) followed by petroleum ether (60/80) (4.4) and acetone (4.5), in conjunction with an ultrasonic

bath (5.8) have been shown to be effective in cleaning the test vessel, cap, and liquid trap.

11.4 All procedures (A & B)

11.4.1 Remove the screw cap from the test vessel and introduce 20,0 ml 0,5 ml of diluent oil (4.1)using the syringe (5.3) and replace the screw cap. Place the test vessel in the temperature controlled

heating jacket and fit the input/output tubing.

11.4.2 Air is pumped through the diluent in the test vessel and to the detector for 5 min. This allows thediluent oil to warm up and the system to be purged.

11.4.3 Air is then pumped directly to the detector bypassing the test vessel to allow the test portion to beintroduced without purge air affecting the concentration of the H2S. Ensure that the instrument is

operating in bypass mode before introducing sample.Introducing the sample before this condition is met

will likely result in premature loss of H2S and an erroneously low result. If this is suspected the test must

be abandoned and repeated. The instrument will warn the user if they attempt to introduce the test portion

before it is operating in bypass mode.

11.4.4 Depending on the expected H2S concentration, draw the appropriate volume of sample from atleast 3 cm below the sample surface, avoiding the bottom of the container, into the disposable syringe(5.5) or 1 ml positive displacement pipette (5.4) and weigh to the nearest 0,001 g (5.2). Avoid applying astrong vacuum to the sample and take care to ensure that the integrity of the material is maintained sothat the possible loss of H2S is kept to a minimum. Do not expel air from the syringe or pipette into thesample. Using the keypad, enter the total mass, which includes the pipette and sample, into theapparatus. The appropriate volume shall be determined by reference to Table 1.

Table 1: Appropriate test volume for expected H2S concentration

Expected H2S concentration

(mg/kg)

Required test volume

(ml)Sample introduction

0 -10 5 Disposable syringe


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10 20 2 Disposable syringe

20+ 1 Pipette

Note A single weight can be entered rather than entering the weight before and after sample introductionif the balance is tared.

11.4.5 Introduce the test portion into the test vessel, ensuring that the syringe or pipette is held verticallyto avoid sample adhering to the test vessel walls. Ensure that the syringe or pipette does not touch the

surface of the diluent liquid. Any pickup of diluent oil onto or into the syringe or pipette will result in the

mass of the oil being included in the mass of the empty syringe or pipette (11.4.7) leading to anerroneously high result. If this is suspected the test must be abandoned and repeated.

11.4.6 Immediately, as soon as the sample has been introduced to the test vessel, fit the screw captightly on to the top of the test vessel.

11.4.7 Weigh the empty syringe or pipette to the nearest 0,001 g (5.2) and using the keypad enter themass into the apparatus.

11.4.8 Start the test. The following actions take place automatically:

11.4.9 The detector reading is normalized to zero.

11.4.10.1 In the case of Procedure A air is pumped directly through the filter cartridge for 3 minutes. After3 minutes air is diverted through the test portion and diluent in the test vessel via the filter cartridge in the

vapour phase processor and then carried to the detector

11.4.10.2 In the case of Procedure B air is pumped directly through the test portion and diluent in the test

vessel and then carried to the detector

11.4.11 The millivolt readings (mV) from the detector are recorded at least every 4 seconds throughoutthe test until 15 minutes have elapsed. The result is automatically calculated and displayed in mg/kg.


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11.4.12 Air is pumped to purge the detector.

11.4.13 Remove and clean the test vessel (11.3.2 11.3.3).

11.4.14 When the test vessel is removed for cleaning, check that the sample and diluent oil have properlymixed. If two distinct phases exist, check the gas connections and repeat the test.

12 Calculation

Calculate the H2S content of the sample, expressed in mg/kg, using the equation:

where:

A is the integrated area of cell output over the test time (mV.s).

M is the calibration constant of the detector (g)/(mV.s).

m is the mass of the sample (g).

13 Expression of results

For all completed tests, record the following:

(i) H2S content to the nearest 0,01 mg/kg for < 10 mg/kg, and to the nearest 0,1 mg/kg for 10mg/kg.

(ii) The procedure followed (A or B)

H SA x M

m2

=


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14 Precision2

14.1 General

The precision values for Residual fuels given in 14.2 and 14.3 were derived from a 2009 laboratory study

which used 7 instruments and 7 operators at a single location, to test 15 samples in duplicate and in

random order. The sample types covered the H2S levels of 0,01 to 15,3 mg/kg and viscosities up to 3 000

mm2s

1at 50C. The precision values for Distillate fuels given in 14.2 and 14.3 were derived from a 2011

laboratory study which used 10 instruments and 10 operators at a single location, to test 8 samples induplicate and in random order. The sample types covered the H2S levels of 0,40 to 9.70 mg/kg.

As the precision was determined from results obtained at a single location the reproducibility may not be

comparable when results obtained at different times and locations are compared, due to sampling,

shipping, storage and environmental factors. In practice two results obtained from different locations

would be acceptable if their difference did not exceed the published reproducibility.

14.2 Repeatability3, r

The difference between two test results, obtained by the same operator with the same apparatus under

constant operating conditions on identical test material would in the long run, in the normal and correct

operation of the test method, exceed the following value in absolute value in only one case in twenty.

14.2.1 Procedure A

r = x.xxxxx

14.2.2 Procedure B

Residual fuels r = 0,2970 X0,6

Distillate fuels r = 0,2099 X0,7

2The round robin research report is available from the Energy Institute.

3 Laboratory studies were carried out at a single location


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where X is the average of the results being compared, in mg/kg.

See Table 2 and Table 3 for a tabular illustration and Annex B for a graphical illustration of thisrelationship.

14.3 Reproducibility3, R

The difference between two single and independent test results, obtained by different operators working

in different laboratories on identical test material, would in the long run, in the normal and correct

operation of the test method, exceed the following value in only one case in twenty.

14.2.1 Procedure A

R = x.xxxxx

14.2.1 Procedure B

Residual fuels R = 0,5232 X0,6

Distillate fuels R = 0,2389 X0.7

where X is the average of the results being compared, in mg/kg.

See Table 2 and Table 3 for a tabular illustration and Annex B for a graphical illustration of thisrelationship.


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15 Test report

The test report shall contain at least the following information:

a) a reference to this standard;

b) the type and complete identification of the product tested;

c) the result of the test (see clause 13);

d) any deviations, by agreement or otherwise, from the procedures specified;

e) the time and date of the test.

f) the procedure followed (A or B)


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Annex A

(normative)

H2S Apparatus

A.1 Apparatus

A.1.1 General

The apparatus1, as shown diagrammatically in Figure A.1 (Procedure A) & A.2 (Procedure B), is self

contained and operates automatically to measure the amount of H2S in liquid samples of fuel oils.

A.1.1.1 Air pump filter, 5 micron nylon encapsulated, to remove dust from the air.

A.1.1.2 Air pump, capable of supplying air at 375 ml/min 55 ml/min. The air is used:

a) To purge the detector, glassware and tubing.

b) To agitate the test portion and diluent mixture.

c) As a carrier for the extracted H2S gas.

A.1.1.3 Inlet air filter, carbon type to remove moisture and contaminants from the air supply.

A.1.1.4 Solenoid valves, to divert the air supply from the test vessel as required during the normal test

sequence and to divert the H2S gas away from the detector, if high levels of H2S are measured that couldsaturate the detector.

A.1.1.5 Flow sensors, electronic sensors incorporated to ensure that the air/H2S gas mixture reaches thedetector, to enable the air flow to be controlled and that any flow problems are detected.

A.1.1.6 Liquid trap, 25 ml borosilicate glass tube with an internal input tube, to trap any liquid or heavy


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vapours. The top half of the tube shall be loosely filled with glass fibre.

A.1.1.7 Moisture filter, 5 micron nylon encapsulated, to remove moisture from the air/H2S mixture.

A.1.1.8 Heater jacket, 50 Watt, aluminium block, controlled to 60,0C 1,0C, with an over temperaturecutout.

A.1.1.9 Temperature probe, platinum resistance thermometer to measure and control the heating jackettemperature.

A.1.1.10 Test vessel, 50 ml borosilicate glass tube with an internal input tube for the air supply. This testvessel is heated by the heater jacket. See Figure A.2

A.1.1.11 H2S detector, electrochemical type specifically for H2S measurement, range (gas)

0-50 ppm (V/V), repeatability 1%, response time T90 < 30 seconds.

A.1.1.12 Vapour Phase Processor (Procedure A only), electrothermal device designed to cool theFilter cartridge (4.6) to -20

oC and allow gases emitted from the test vessel to pass through the Filter

cartridge and then to the H2S detector


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Figure A.1: H2S apparatus with Vapour Phase Processor (Procedure A)

Figure A.2: H2S apparatus (Procedure B)


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Figure A.3: Test vessel


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Figure A.4 Sorbent Cartridge

Key

! # %

' ( ! ) 1 ) 2 1 2 ) 3 4 1 # 5 3

6 7 8 9 @ B 5 1 D 3 1 5 0 % 1 3 E G @ P

@ ! ) 1 R %

( S 3 # 5 ) 4 1 # 5 3

T U V

W # & % 3


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Appendix C


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The following was the previous precision estimates with Sample 2 in place before it wasrealized that the whole sample should be removed. It is referred to in the letter

accompanying the precision estimate above and hence is included. The precision

estimate dated 16th February, 2012 is the one used.


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Appendix D

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Documents

Marine Fuel h2s Round Robin Research Report March 6th 2012