supplementary comparison coomet.qm-s4 - bipm · 2019-07-09 · supplementary comparison...

1

Supplementary Comparison COOMET.QM-S4

“С2-С5 components in mixtures of liquified hydrocarbons”

Final report L.A. Konopelko1, Y.A. Kustikov1, A.V. Kolobova1, A. V. Meshkov1, O V Efremova1, M. Rozh-

nov2, D. Melnyk2, S. Kisel2, O. Levbarg2, S. Shpilnyi2, S. Yakubov2, A.M. Mironchik3, M.V.

Mokhnach3, V.N. Ananyin3.

1D.I.Mendeleyev Institute for Metrology, 19, Moskovsky pr., St-Petersburg, 190005, Russia.

2All-Ukrainian State Research and Production Center of Standardization, Metrology, Certifi-

cation and Consumers Rights Protection, 4, Metrologicheskaya str., Kiev, 03143, Ukraine. 3Belorussian State Institute for Metrology, Section for physico-chemical and optical measure-

ments, sector for standards and gas mixtures, 8, Serova st., Minsk, Belarus.

Field Amount of substance

Subject Comparison of the composition of liquefied petroleum gas (С2-С5 components)

Table of contents Field ............................................................................................................................ 1

Subject ........................................................................................................................ 1

Table of contents ........................................................................................................ 1

1 Introduction ............................................................................................................. 2

2 Design and organisation of comparison .................................................................. 2

2.1 Participants ……...................................................................................................2

2.2 Measurement standards………………………………………………………….2

2.3 The schedule……………………………………………………………………..3

2.4 Measurement methods and calibration procedures………………………..…….3

3 Results ..................................................................................................................... 4

4 Supported CMC claims ........................................................................................... 8

5 Discussion and conclusions ..................................................................................... 8

6 References ............................................................................................................... 8

Annex A – Purity data……………………………………………………………….9

Annex B - Calculation of reference values accounting for possible instability ……11

Annex C – Measurement reports from participants

Measurement report from BelGIM .................................................................. 15

Measurement report from Ukrmetrteststandard .............................................. 21

Measurement report from VNIIM ................................................................... 26

2

1 Introduction

The objective of the present supplementary comparison is assessment of the analytical capabilities of

laboratories for measuring the composition of a Liquid Petroleum Gas (LPG) mixtures when sampled in

the liquid phase from Constant Pressure Cylinders (CPCs).

This comparison was organized by VNIIM within Technical Committee 1.8 “Physical Chemistry”

COOMET.

In 2015 VNIIM participated in the similar CCQM comparison - CCQM-K119 «Liquified Petroleum

Gas»[1] and showed the equivalent results.

2 Design and organization of comparison

2.1 Participants

Table 1 lists the participants of the comparison.

Table 1: List of participants

Acronym Country Institute

VNIIM RU D.I.Mendeleyev Institute for Metrology, St-Petersburg, Rus-sia

Ukrmetrt-

eststandart

UA All-Ukrainian State Research and Production Center of Standardization, Metrology, Certification and Consumers Rights Protection, Kiev, Ukraine

BelGIM BY Belorussian State Institute for Metrology, Minsk, Belarus

2.2 Measurement standards

A suite of mixtures (4 travelling standards) has been prepared at VNIIM for this comparison. Table

2 shows the nominal composition of the mixtures (expressed as amount of substance fractions).

Table 2: Nominal composition of the mixtures

Component Amount fraction,

cmol/mol

Ethane 2

Propene 9

n-Butane 10

1-Butene 3

i-Butane 4

i-Pentane 1

Propane 71

The calculation procedures of ISO 6142-1[2] and ISO 19229[3] were used to calculate the amount-

of-substance fractions and associated standard uncertainties. These mixtures were prepared in constant

pressure cylinders (CPC), V=1 dm3, produced by Monitoring LTD (Russia). Components were added

to CPC in order of increasing boiling point. After filling the CPCs were pressurized with He to 2.0

MPa.

Purity analysis of the parent substances was carried out by GC- FID, TCD. Results of purity analysis

are shown in the Annex A.

The travelling standards were verified by establishing consistency within the suite and also were

compared to VNIIM Primary Reference Standard (PSM) - a liquid mixture with the same nominal

composition also prepared in a CPC (V=2 dm3).

From 2 to 5 measurements (GC-FID) were carried out before shipping depending on the shipping

date of the travelling standard. Measurements were performed also after return of the travelling stand-

ards to assess stability of mixtures.

3

Stability was estimated by measurements against VNIIM PSM and also by application of method of

internal normalization.

2.3 Measurement methods and calibration procedures

Measurement and calibration methods are summarized in the table 3.

Table 3 Measurement and calibration methods

Laboratory Measurement

method

Calibration

method

Total number of measure-

ments

Ukrmetrteststandart GC-FID linear model ISO

6143:2001

3 primary standard

gas mixtures, pre-

pared in house

4 measurements

4 sub-measurements

BelGIM GC-FID ISO 7941:1988

One point calibra-

tion

2 own standards of

LPG

3 measurements

3 sub-measurements

VNIIM GC-FID GOST R 54484-

2011

One point calibra-

tion

1 own standard

3 measurements

4-6 sub-measurements

2.4 The schedule

The schedule for the comparison is shown in table 4.

Table 4: The schedule for the comparison

Date Event

January 2017 Final protocol published

February - March 2017

Preparation and verification of mixtures

April 2017 Distribution of cylinders

May-June 2017 Analysis of the mixtures by participants

July - August 2017 Participants reports are sent to coordinator and return of the cylinders

September 2017 Reanalysis of the mixtures at VNIIM

October 2017 Resending the cylinder to Ukrmetrteststandart due to technical problems

January - May 2018 Analysis of the mixture in Ukrmetrteststandart

June 2018 Ukrmetrteststandart sent the report to VNIIM

August 2018 Return of the Ukrmetrteststandart cylinder to VNIIM

September 2018 Reanalysis of the Ukrmetrteststandart mixture at VNIIM

Осtober 2018 Draft A report available

January 2019 Draft B report available

Note – The initial schedule of the comparison has been moved significantly due to repeated ship-

ping of the travelling standard to Ukraine and delivery of travelling standard from RF to Ukraine

through a third country.

4

3 Results

The degree of equivalence (Dij) for each participating laboratory and each component is defined in

accordance with the equation:

refij, jiji xx=D -

(1)

Where, xij is the reported amount fraction of component j from laboratory i and xij,ref is the

comparison reference value of component j from the mixture delivered to laboratory i. The

combined standard uncertainty of Dij thus can be expressed as:

)x(u)x(u)x(u)x(u)x(u)D(u ver,ij

2

prep,ij

2

ij

2

ref,ij

2

ij

2

ij

2 ++=+== (2)

where u(xij) is the standard uncertainty of the reported by laboratory amount fraction of component j,

u(xij,prep) is the standard uncertainty in the amount of substance fraction from preparation and u(xij,ver)

is the uncertainty from verification.

The expanded uncertainty )U(D jiof Dij at a 95 % confidence level is calculated using the following

equation:

2

verij,

2

prepij,

2

ijij u+u+uk=)U(D (3)

where k is the coverage factor, (k=2).

In the comparison the stability of each component was monitored (before and after distribution) and

for one of the travelling standards (for Ukrmetrteststandart travelling standard (cylinder №1310), for

which the time period before and after distribution measurements was about a year) some trend was

registered for several components. This trend was tested for significance, and was found to be insig-

nificant as the slope (b) of time dependence of concentration satisfied to inequality (4)

b t0,95,k-2s(b) (4)

where s(b) is the standard deviation of b, t0,95,n-2 - Student coefficient for f=n-2 degrees of freedom and

P=0.95.

For other travelling standards trend was not observed within the accuracy of measurements.

Thus gravimetric values were adopted as reference values for all the comparison travelling standards.

Another approach for reference values which accounts for some instability is shown in the Annex B,

which also contains results of calculations for inequality (4).

5

Lab/

Cylinder № Component

xij,ref

(xij,prep),

cmol/mol

uij,ref,

cmol/mol

xij,

cmol/mol

u(xij),

cmol/mol

Dij,

cmol/mol

U(Dij),

cmol/mol Dij rel,%

U(Dij)

rel,%

BelGIM/

1066

Ethane 2,0030 0,0078 1,99 0,02 -0,013 0,043 -0,65 2,14

Propene 8,8186 0,0121 8,82 0,03 0,001 0,065 0,02 0,73

n-Butane 10,0732 0,0228 10,10 0,03 0,027 0,075 0,27 0,75

1-Butene 3,0054 0,0062 3,01 0,02 0,005 0,032 0,15 1,08

i-Butane 4,0606 0,0132 4,07 0,02 0,009 0,048 0,23 1,18

i-Pentane 0,9951 0,0048 1,00 0,01 0,002 0,022 0,19 2,23

Propane 71,031 0,053 71,0 0,15 -0,03 0,32 -0,04 0,45

Ukrmetrt-

eststandart/

1310

Ethane 2,0144 0,0067 2,026 0,018 0,012 0,038 0,58 1,91

Propene 9,4211 0,0098 9,444 0,031 0,023 0,065 0,24 0,69

n-Butane 9,9599 0,0288 9,953 0,045 -0,007 0,107 -0,07 1,07

1-Butene 3,0694 0,0078 3,047 0,014 -0,022 0,032 -0,73 1,05

i-Butane 4,0532 0,0087 4,055 0,018 0,002 0,039 0,04 0,97

i-Pentane 0,9873 0,0045 0,986 0,010 -0,001 0,022 -0,13 2,22

Propane 70,482 0,033 70,49 0,25 0,01 0,50 0,01 0,72

VNIIM/

1306

Ethane 2,0173 0,0055 2,016 0,009 -0,001 0,021 -0,06 1,02

Propene 8,8798 0,0094 8,867 0,014 -0,013 0,033 -0,14 0,37

n-Butane 10,0778 0,0244 10,13 0,025 0,052 0,070 0,52 0,69

1-Butene 2,9782 0,0046 2,983 0,006 0,005 0,015 0,16 0,50

i-Butane 4,0218 0,0078 4,038 0,008 0,016 0,023 0,40 0,56

i-Pentane 0,9985 0,0037 0,996 0,005 -0,003 0,012 -0,25 1,19

Propane 71,014 0,033 70,97 0,072 -0,044 0,158 -0,06 0,22

Table 5 Results of COOMET.QM-S4

The results are presented graphically in the figures 1-7.

6

Figure 1. Results for Ethane

Figure 2. Results for Propene

Figure 3. Results for n-Butane

-5-4,5

-4-3,5

-3-2,5

-2-1,5

-1-0,5

00,5

11,5

22,5

3

VNIIM BelGIM Ukrmetrteststandart

Di,

rel

ati

ve

dev

iati

on

fro

m

refe

ren

ce v

alu

e, %

Ethane

-2

-1,6

-1,2

-0,8

-0,4

0

0,4

0,8

1,2

1,6

2


Di,

rel

ati

ve d

evia

tion

fro

m

refe

ren

ce v

alu

e, %

Propene

-2

-1,6

-1,2

-0,8

-0,4

0

0,4

0,8

1,2

1,6

2


Di,

rel

ati

ve

dev

iati

on

fro

m

refe

ren

ce

va

lue,

%

n-Butane

7

Figure 4. Results for 1-Butеne

Figure 5. Results for i-Butane

Figure 6. Results for i-Pentane

-2

-1,6

-1,2

-0,8

-0,4

0

0,4

0,8

1,2

1,6

2


Di,

rel

ati

ve

dev

iati

on

fro

m

refe

ren

ce v

alu

e, %

1-Butеne

-2

-1,6

-1,2

-0,8

-0,4

0

0,4

0,8

1,2

1,6

2


Di,

rel

ati

ve

dev

iati

on

fro

m

refe

ren

ce v

alu

e, %

i-Butane

-5

-4

-3

-2

-1

0

1

2

3

4

5


Di,

rel

ati

ve

dev

iati

on

fro

m

refe

ren

ce v

alu

e, %

i-Pentane

8

Figure 7. Results for Propane

4 Supported CMC claims

The results of this supplementary comparison can be used to support CMC claims for ethane, pro-

pane, propene, i-butane, n-butane, 1-butene and i-pentane in the liquid phase in CPCs with a matrix

of propane, n- butane or i-butane.

The support of CMC claims is described in more detail in the GAWG strategy for comparisons and

CMC claims.[4]

5 Conclusions

The results in this supplementary comparison demonstrate good comparability between laboratories

within the stated uncertainties.

References

[1] M.L. Downey, P.J. Brewer, R.J.C. Brown, A.S. Brown, Milton MJT, A.M.H. van der

Veen, E.T. Zalewska and others, International comparison CCQM-K119 “Liquefied petroleum

gas”, Final report, KCDB BIPM (2017).

[2] ISO 6142-1:2015, Gas analysis -- Preparation of calibration gas mixtures -- Part 1: Grav-

imetric method for Class I mixtures, (2015).

[3] ISO 19229:2015, Gas analysis -- Purity analysis and the treatment of purity data, (2015).

[4] Brewer PJ, van der Veen AMH, GAWG strategy for comparisons and CMC claims,

CCQM Gas Analysis Working Group, (2016).

Date: 03/10/2018

-2

-1,6

-1,2

-0,8

-0,4

0

0,4

0,8

1,2

1,6

2


Di,

rel

ati

ve

dev

iati

on

fro

m

refe

ren

ce v

alu

e, %

Propane

9

Annex A

Purity data

Table A1 - Purity data for ethane

Component Amount fraction

cmol/mol

Expanded uncertainty (k=3)

cmol/mol

ethane 99.99988 -

n-butane 0.00012 0.00003

Table A2 - Purity data for propene


cmol/mol


cmol/mol

propene 99.97184 —

propane 0.0209 0.0025

nitrogen 0.0070 0.0021

i-butane 0.00026 0.00008

Table A3 - Purity data for n-butane


cmol/mol


cmol/mol

n-butane 99.97095 —

neo-pentane 0.0244 0.0020

i-butane 0.0031 0.0005

trans-2-butene 0.00088 0.00026

cis-2-butene 0.00037 0.00011

propane 0.00030 0.00009

Table A4 - Purity data for 1-butene


cmol/mol


cmol/mol

1-butene 99.4508 —

n-butane 0.243 0.017

i-butene (2-methylpro-

pene) 0.124 0.025

i-butane 0.093 0.007

nitrogen 0.059 0.018

trans-2-butene 0.0103 0.0021

oxygen 0.010 0.003

propene 0.0058 0.0007

propane 0.0017 0.0005

1,3- butadiene 0.0014 0.0004

cis-2-butene 0.0010 0.0003

10

Table A5 - Purity data for i-butane


cmol/mol


cmol/mol

i-butane 99.97725 —

n-butane 0.012 0.003

propane 0.0102 0.0012

i-butene 0.00055 0.00017

Table A6- Purity data for i-pentane


cmol/mol

Expanded uncertainty

(k=3)

cmol/mol

i-pentane 99.6822 -

n-pentane 0.2546 0.0764

neo-pentane 0.043 0.013

toluene 0.0072 0.0022

n-heptane 0.0030 0.0009

n-hexane 0.0027 0.0008

1-hexene 0.0016 0.0005

2-methyl-1-butene 0.0016 0.0005

cyclohexane 0.00115 0.00004

1-pentene 0.00057 0.00017

n-butane 0.00051 0.00015

n-nonane 0.00047 0.00014

cyclopentane 0.00029 0.00009

3-methyl-1-butene 0.00020 0.00006

2,2-dimethylbutane 0.00018 0.00005

2-methyl-2-butene 0.00014 0.00004

benzene 0.00012 0.00004

n-octane 0.00010 0.00003

trans-2-pentene 0.00010 0.00003

2-methylpentane 0.00009 0.00003

3-methylpentane 0.000077 0.000023

Table A7 - Purity data for propane


cmol/mol


cmol/mol

propane 99.9957 —

n-butane 0.0029 0.0004

propene 0.00076 0.00019

ethane 0.00035 0.00011

i-butane 0.00025 0.00007

11

Annex B

Calculation of reference values accounting for possible instability

The approach for calculation of reference values considering some instability was applied only for

cylinder №1310 (Ukrmetrteststandart travelling standard) for which the time period before and after

distribution measurements was about a year. The corrections were determined from linear regression

of the time dependance of the results of measurements.

In this case the reference values xij,ref have been calculated according to the equation:

stab,ijprep,ijrefij, xxx += (1B)

where xij,prep is the amount of substance fraction from preparation, xij,stab is a drift correction for j

component determined from its regression at the time when it was analysed by the participant

The appropriate combined standard uncertainty of Dij - u (Dij) was calculated in accordance with (2B)

)x(u)x(u)x(u)x(u)D(u stab,ij

2

ver,ij

2

prep,ij

2

ij

2

ij

2 +++== (2B)

where u(xij,stab) is the standard uncertainty of the drift correction.

Table 1B provides the reference values and results from the comparison in accordance with this ap-

proach.

12

Lab/

Cylinder № Component

xij,prep, cmol/mol

xij,stab xij,ref uij,ref,

cmol/mol

xij,

cmol/mol

u(xij),

cmol/mol

Dij,

cmol/mol

U(Dij),

cmol/mol Dij rel,% U(Dij)rel,%

BelGIM/

1066

Ethane 2,0030 - 2,0030 0,0078 1,99 0,02 -0,013 0,043 -0,65 2,14

Propene 8,8186 - 8,8186 0,0121 8,82 0,03 0,001 0,065 0,02 0,73

n-Butane 10,0732 - 10,0732 0,0228 10,10 0,03 0,027 0,075 0,27 0,75

1-Butene 3,0054 - 3,0054 0,0062 3,01 0,02 0,005 0,032 0,15 1,08

i-Butane 4,0606 - 4,0606 0,0132 4,07 0,02 0,009 0,048 0,23 1,18

i-Pentane 0,9951 - 0,9951 0,0048 1,00 0,01 0,002 0,022 0,19 2,23

Propane 71,031 - 71,031 0,0529 71,0 0,15 -0,031 0,318 -0,04 0,45

Ukrmetrt-

eststandart/

1310

Ethane 2,0144 -0,0335 1,9809 0,0207 2,026 0,018 0,045 0,055 2,27 2,77

Propene 9,4211 0,0071 9,4282 0,0421 9,444 0,031 0,016 0,105 0,17 1,11

n-Butane 9,9599 -0,0845 9,8754 0,0173 9,953 0,045 0,078 0,096 0,79 0,98

1-Butene 3,0694 -0,0068 3,0626 0,0678 3,047 0,014 -0,016 0,139 -0,51 4,52

i-Butane 4,0532 -0,0045 4,0487 0,0216 4,055 0,018 0,006 0,140 0,16 3,47

i-Pentane 0,9873 -0,0099 0,9774 0,0097 0,986 0,010 0,009 0,028 0,88 2,85

Propane 70,482 0,1448 70,6268 0,1334 70,49 0,25 -0,137 0,567 -0,19 0,80

VNIIM/

1306

Ethane 2,0173 - 2,0173 0,0055 2,016 0,009 -0,001 0,021 -0,06 1,02

Propene 8,8798 - 8,8798 0,0094 8,867 0,014 -0,013 0,033 -0,14 0,37

n-Butane 10,0778 - 10,0778 0,0244 10,13 0,025 0,052 0,070 0,52 0,69

1-Butene 2,9782 - 2,9782 0,0046 2,983 0,006 0,005 0,015 0,16 0,50

i-Butane 4,0218 - 4,0218 0,0078 4,038 0,008 0,016 0,023 0,40 0,56

i-Pentane 0,9985 - 0,9985 0,0037 0,996 0,005 -0,003 0,012 -0,25 1,19

Propane 71,014 - 71,014 0,0326 70,97 0,072 -0,044 0,158 -0,06 0,22

Table 1B. Results of COOMET.QM-S4

13

Figures 1B and 2B show the graphs for the results of measurements for cylinder №1310 during

the comparison period

The data for the graphs are shown below in the table 2B.

Figure 1B

Figure 2B

Note – range of sdandard deviation for each day measurement is shwn in the Table 2B.

y = -7E-05x + 2,0093

y = -0,0001x + 9,4648

y = 4E-06x + 4,0446

y = -6E-05x + 9,895

y = 9E-06x + 3,057

y = -3E-05x + 0,9769

0,00

1,00

2,00

3,00

4,00

5,00

6,00

7,00

8,00

9,00

10,00

11,00

0 100 200 300 400 500 600

Mea

sure

d a

mo

un

t fr

acti

on

, cm

ol/

mo

l

Days after preparation

Stability data for cylinder №1310

n-butane

propene

i-butane

butene-1

ethane

i-pentane

y = 0,0003x + 70,596

65,00

66,00

67,00

68,00

69,00

70,00

71,00

72,00

0 100 200 300 400 500 600

Mea

sure

d a

mo

un

t fr

acti

on

, cm

ol/

mo

l

Days after preparation

Stability data for cylinder № 1310, propane

propane

14

Measured amount fraction, cmol/mol SD for each

day measure-

ment, % rel Date 27.03.2017 15.05.2017 05.07.2017 19.09.2017 20.09.2018

Number of days

Component 1 51 102 178 543

Ethane 2,0144 1,9867 2,0271 1,9855 1,9733 0,3-0,75

Propene 9,4211 9,4652 9,5069 9,4343 9,3926 0,1-0,4

i-Butane 4,0532 4,0487 4,0227 4,0545 4,0475 0,2-0,45

n-Butane 9,9599 9,8960 9,8066 9,8829 9,8795 0,4-0,7

1-Butene 3,0694 3,0712 3,0288 3,0572 3,0667 0,2-0,4

i-Pentane 0,9873 0,9690 0,9746 0,9638 0,9641 0,2-1,0

Propane 70,482 70,5986 70,7584 70,6729 70,7227 0,1-0,2

Table 2B. Stability data for cylinder №1310

Table 3B contains data on the assessment of the significance of the slope of the depend-

ence of the amount of substance on time

Component |b| s(b) t0,95,n-2 s(b)

(t0,95,k-2=3,18)

Conclusion

Ethane 710-5 4,510-5

14,310-5 b t0,95,k-2 S(b)

the slope is insignificant

Propene 0,00012 0,000095 0,00030

b t0,95,k-2 S(b)


n-Butane 5,610-5 1410-5 4510-5 b t0,95,k-2 S(b)


1-Butene 9,310-6 4,710-5

14,810-5

b t0,95,k-2 S(b)


i-Butane 3,810-6 3,510-5 11,110-5 b t0,95,k-2 S(b)


i-Pentane 2,910-5 1,9810-5 6,2910-5 b t0,95,k-2 S(b)


Propane 0,00030 0,00024

0,00076

b t0,95,k-2 S(b)


Table 3B. Testing of the slope b, (cmol/mol)/day, of time dependence of amount of substance

for significance

15

Annex C

Reports submitted by participating laboratories

Report of BelGIM

COOMET No 622/RU/13 Supplementary comparison

«C3-C5 components in mixtures of liquefied hydrocarbons»

REPORT ON THE RESULTS OF THE STUDY

I. Results of experimental studies

Laboratory: Belarus, BelGIM, Section for physicochemical and optical measurements, sector for standards and gas mixtures, 8, Serova st., Minsk.

Cylinder No: 1066

Measurement No 1

Component Date

dd/mm/yy

Result, 10-2 mol/mol

Standard deviation, % relative

Number of replicates,

n

Ethane 28/04/17 1,9946 0,027 4

Propene 28/04/17 8,816 0,012 4

n-Butane 28/04/17 10,102 0,05 4

1-Butene 28/04/17 3,012 0,05 4

iso-Butane 28/04/17 4,069 0,04 4

iso-Pentane 28/04/17 0,9964 0,08 4

Propane 28/04/17 71,009 0,011 4

Measurement No 2

Component Date

dd/mm/yy




n

Ethane 04/05/17 1,9958 0,009 4

Propene 04/05/17 8,813 0,015 4

n-Butane 04/05/17 10,097 0,03 4

1-Butene 04/05/17 3,008 0,029 4

iso-Butane 04/05/17 4,068 0,019 4

iso-Pentane 04/05/17 0,9988 0,03 4

Propane 04/05/17 71,019 0,005 4

16

Measurement No 3

Component Date

dd/mm/yy




n

Ethane 17/05/17 1,9919 0,04 4

Propene 17/05/17 8,821 0,018 4

n-Butane 17/05/17 10,106 0,020 4

1-Butene 17/05/17 3,010 0,027 4

iso-Butane 17/05/17 4,074 0,014 4

iso-Pentane 17/05/17 0,9948 0,07 4

Propane 17/05/17 71,003 0,005 4

Final results:

Component Result,

10-2 mol/mol Coverage factor

Expanded uncertainty, 10-2 mol/mol

Ethane 1,99 2 0,04

Propene 8,82 2 0,06

n-Butane 10,10 2 0,06

1-Butene 3,01 2 0,03

iso-Butane 4,07 2 0,04

iso-Pentane 0,997 2 0,010

Propane 71,0 2 0,3

17

II. Description of the study

Equipment

Gas chromatograph Trace GC Ultra with FID, 6-port gas sampling valve with 0.125 ml sampling

loop, column TG-BOND Alumina (KCl) 50 m × 0,53 mm × 10 µm.

Carrier gas: He grade 6.0.

High purity hydrogen and compressed air for FID.

Data collection: Software Xcalibur 2.1.

Liquid sample vaporization manifold PerkinElmer Model Arnel 4085 for sample gasification.

Calibration standards (CS)

Calibration was performed using two reference mixtures of liquefied hydrocarbons similar in com-

position to the sample for comparison. CSs were prepared in constant pressure (piston) cylinders

(CPC) model CP-2GM with a volume of 1 liter (Welker, USA). CPCs were equipped with tracker

magnet, gravity mixer, two manometers for the pressure control in the sample chamber and in

the working gas chamber, three valves.

CS composition was calculated from the gravimetric preparation process according to

ISO 6142-1:2015 and was verified according to ISO 7941:1988 and using measurement proce-

dure developed in BelGIM. CS preparation was carried out by direct mixing of the initial compo-

nents in a previously evacuated CPC. Components were added in CPC in order of increasing

boiling point. All initial components were purity analyzed before use by GC-FID according to

ISO 7941:1988 and using measurement procedure developed in BelGIM.

Composition of CSs are given in table 1.

18

Table 1 – RMLH composition

Component

CS1 (CPC No 32279) CS2 (CPC No 32280)

Amount frac-tion,

10-2 mol/mol

Relative ex-panded uncer-

tainty (k=2, P=0,95), %

Amount frac-tion,

10-2 mol/mol

Relative ex-panded uncer-

tainty (k=2, P=0,95), %

Ethane 4,37 2,0 2,15 2,0

Propene 8,82 0,5 8,91 0,5

n-Butane 9,74 0,5 10,06 0,5

1-Butene 3,000 1,0 3,18 1,0

iso-Butane 3,92 1,0 4,04 1,0

iso-Pentane 1,034 1,0 0,989 1,0

Propane 69,10 0,3 70,67 0,3

GC calibration

Molar fraction of each component j in the sample for comparison was calculated by the internal

normalization technique according to ISO 7941:1988. Molar correction factor 𝐾𝑗 for each compo-

nent j was established by GC calibration with CS1 и CS2.

Sequence of measurements:

1) CS1 – sample for comparison – CS2



Since preparation of each sample and its measurement required more than 8 hours, calibration,

measurement and re-calibration were carried out for three days day after day.

The chromatograms of each CS were recorded at least three times.

For each chromatogram, the molar correction factor 𝐾𝑗 was calculated by the formula

𝐾𝑗 =𝐴𝐶3𝐻8𝑟𝑒𝑓

∙ 𝑋𝑗𝑟𝑒𝑓

𝑋𝐶3𝐻8𝑟𝑒𝑓

∙ 𝐴𝑗𝑟𝑒𝑓

(1)

where

𝐴𝐶3𝐻8𝑟𝑒𝑓

– peak area of propane, counts;

𝑋𝑗𝑟𝑒𝑓

– molar fraction of the component j in the CS, 10-2 mol/mol;

𝑋𝐶3𝐻8𝑟𝑒𝑓

– molar fraction of propane in the CS, 10-2 mol/mol;

𝐴𝑗𝑟𝑒𝑓

– peak area of the component j, counts.

To calculate the measurement result, the arithmetic mean of the molar correction factor values

established by CS1 and CS2 was used.

19

Sample handling

Before calibration (measurements) CPC with CS and the sample for comparison were kept at

room temperature for at least 24 hours. Helium was injected into the working gas chamber of

CPC to a pressure of 1.6 MPa.

CSs were homogenized with a gravity mixer.

A sample of a 20 ml CS (sample for comparison) was taken to a previously evacuated vaporiza-

tion manifold Arnel 4085 and was kept until complete evaporation and homogenization for at least

18 hours. The helium pressure in the working gas chamber of CPC during sample collection into

the vaporization manifold was maintained at 1.6 MPa.

During calibration (measurements) gas sample was fed into 6-port gas sampling valve via re-

strictor and stainless steel tube at a flow rate of 20 ml/min.

Uncertainty calculation

Molar fraction of the component j in the sample for comparison 𝑋𝑗, 10-2 mol/mol, was calculated

by the formula

𝑋𝑗 =𝐾𝑗 ∙ 𝐴𝑗

∑ 𝐾𝑗 ∙ 𝐴𝑗𝑚𝑗=1

∙ 100 (2)

where

𝐾𝑗 – molar correction factor of the component j;

𝐴𝑗 – peak area of the component j, counts;

𝑚 – number of components in the sample for comparison.

Relative summary standard uncertainty of measurement of molar fraction of component j in the

sample for comparison 𝑢𝑜(𝑋𝑗), %, was calculated by the formula

𝑢о(𝑋𝑗) = √[𝑢(𝑋𝑗)𝑜𝐴]2 + [𝑢(𝐾𝑗)𝑜𝐴]

2 + [𝑢(𝐾𝑗)𝑜𝐵]2, (3)

where

𝑢(𝑋𝑗)𝑜𝐴 – experimental relative standard deviation of the measurements results of the compo-

nent j, %;

𝑢(𝐾𝑗)𝑜𝐴 – experimental relative standard deviation of the molar correction factor of the compo-

nent j, %;

𝑢(𝐾𝑗)𝑜𝐵 – relative standard uncertainty of the molar correction factor of the component j due to

the uncertainty of the CS, %,

𝑢(𝐾𝑗)𝑜𝐵 = √[𝑢(𝑋𝑗𝑟𝑒𝑓

)𝑜]2+ [𝑢(𝑋𝐶3𝐻8

𝑟𝑒𝑓)𝑜]

2, (4)

where

20

𝑢(𝑋𝑗𝑟𝑒𝑓

)𝑜 – relative standard uncertainty of the molar fraction of the component j of the CS, %;

𝑢(𝑋𝐶3𝐻8𝑟𝑒𝑓

)𝑜 - relative standard uncertainty of the molar fraction of propane of the CS, %.

Total standard uncertainty of the molar fraction of the component j in the sample for comparison

𝑢(𝑋𝑗), 10-2 mol/mol, was calculated by the formula

𝑢(𝑋𝑗) =𝑢о(𝑋𝑗) ∙ 𝑋𝑗

100%. (5)

где 𝑋𝑗 – measurement result, 10-2 mol/mol.

Evaluation of measurement uncertainty is given in table 2.

Table 2

Compo-nent

Components of uncertainty Total rela-tive stand-ard uncer-

tainty 𝑢о(𝑋𝑗),

%

Total stand-ard uncer-

tainty 𝑢(𝑋𝑗),

10-2 mol/mol

Coverage factor

Expended uncer-tainty 𝑈(𝑋𝑗),

10-2 mol/mol

𝑢(𝑋𝑗)𝑜𝐴,

%

𝑢(𝐾𝑗)𝑜𝐴,

%

𝑢(𝐾𝑗)𝑜𝐵,

%

Ethane 0,03 0,03 1,0 1,0 0,020 2 0,04

Propene 0,01 0,03 0,3 0,3 0,03 2 0,06

n-Butane 0,02 0,03 0,3 0,3 0,03 2 0,06

1-Butene 0,03 0,04 0,5 0,5 0,015 2 0,03

iso-Butane 0,02 0,03 0,5 0,5 0,020 2 0,04

iso-Pen-tane

0,06 0,07 0,5 0,5 0,005 2 0,010

Propane 0,005 - 0,21 0,21 0,15 2 0,30

21

Report of Ukrmetrteststandart

COOMET.QM-S4 Supplementary comparison

«Liquefied Petroleum Gas»

MEASUREMENT REPORT

I. Results of the study

Laboratory: Ukrmetrteststandart, Kiev, Ukraine

Cylinder number: 1310

Measurement

No 1

Date

dd/mm/yy Result, cmol/mol

Relative standard devia-

tion, %

Number of repli-

cates,

n

Ethane C2H6 21.05.2018 2,031 0,16 4

Propene C3H6 21.05.2018 9,444 0,09 4

n-Butane n-C4H10 21.05.2018 9,961 0,16 4

Butene 1-C4H8 21.05.2018 3,049 0,21 4

iso-Butane i-C4H10 21.05.2018 4,059 0,21 4

iso-Pentane i-C5H12 21.05.2018 0,9889 0,19 4

Propane C3H8 21.05.2018 70,468 0,11 4

Measurement

No 2

Date



tion, %

Number of repli-

cates,

n

Ethane C2H6 22.05.2018 2,0330 0,07 4

Propene C3H6 22.05.2018 9,448 0,05 4

n-Butane n-C4H10 22.05.2018 9,958 0,02 4

Butene 1-C4H8 22.05.2018 3,047 0,05 4

iso-Butane i-C4H10 22.05.2018 4,056 0,03 4

iso-Pentane i-C5H12 22.05.2018 0,9898 0,04 4

Propane C3H8 22.05.2018 70,467 0,03 4

Measurement

No 3

Date



tion, %

Number of repli-

cates,

n

Ethane C2H6 23.05.2018 2,0087 0,02 4

Propene C3H6 23.05.2018 9,439 0,03 4

n-Butane n-C4H10 23.05.2018 9,942 0,04 4

Butene 1-C4H8 23.05.2018 3,045 0,06 4

iso-Butane i-C4H10 23.05.2018 4,046 0,04 4

iso-Pentane i-C5H12 23.05.2018 0,9767 0,06 4

Propane C3H8 23.05.2018 70,544 0,03 4

22

Measurement

No 4

Date



tion, %

Number of repli-

cates,

n

Ethane C2H6 24.05.2018 2,031 0,1 4

Propene C3H6 24.05.2018 9,447 0,1 4

n-Butane n-C4H10 24.05.2018 9,951 0,16 4

Butene 1-C4H8 24.05.2018 3,048 0,08 4

iso-Butane i-C4H10 24.05.2018 4,060 0,15 4

iso-Pentane i-C5H12 24.05.2018 0,9891 0,07 4

Propane C3H8 24.05.2018 70,473 0,07 4

Final results

Component

Mole fraction, cmol/mol

Coverage factor Expanded uncertainty,

cmol/mol

Ethane C2H6 2,026 2 0,036

Propene C3H6 9,444 2 0,062

n-Butane n-C4H10 9,953 2 0,090

Butene 1-C4H8 3,047 2 0,027

iso-Butane i-C4H10 4,055 2 0,036

iso-Pentane i-C5H12 0,986 2 0,019

Propane C3H8 70,49 2 0,49

II. Description of the study

Principle

Sample of the LPG mixture to be analysed (of mass about 14 g) was transferred from the

constant pressure cylinder to the evacuated gas cylinder, where it was vaporised and diluted with

pure nitrogen (of mass about 160 g). The resulting gas mixture was analysed using gas chromato-

graph by comparison with the primary standard gas mixtures of similar composition. Analysis

results were normalised to 100 % of hydrocarbons.

Instrumentation

Balance used for primary standard gas mixtures (PSGM) preparation by gravimetric

method: Mettler Toledo XP26003L electronic balance (max. load 26,1 kg; min. 0,2 g; standard

deviation 0,003 g), with mass pieces traceable to PTB.

Measurement data were collected automatically.

Instruments for purity analysis of parent gases: Agilent 6890N gas chromatographs with

helium ionization detector (HID), flame ionization detector (FID), thermal conductivity detector

(TCD) and mass spectrometric detector (MSD), and gas analysers.

Gas mixture was analysed using Agilent 6890N gas chromatograph with FID. Capillary

column GS-ALUMINA, 50 m, 0,530 mm. Split mode 10:1. Carrier gas – helium, flow rate

5,2 cm3/min. tdetector = 110 ºС.

Calibration Standards

Composition of the calibration standards – primary standard gas mixtures (PSGM) used

for measurements by comparison method is given in the table below

23

Component

PSGM -1

Cylinder No 61032

PSGM -2

Cylinder No 27277

PSGM -3

Cylinder No 13746327

x, % u(x), % x, % u(x), % x, % u(x), %

Ethane C2H6 0,0990 0,0003 0,1051 0,0003 0,1142 0,0003

Propene C3H6 0,45472 0,00023 0,47165 00023 0,50734 00023 n-Butane n-

C4H10 0,47494 0,00017 0,49964 0,00017 0,53802 0,00017

Butene 1-

C4H8 0,14004 0,00017 0,15087 0,00017 0,16713 0,00017

iso-Butane i-

C4H10 0,19151 0,00016 0,20266 0,00016 0,22172 0,00016

iso-Pentane i-

C5H12 0,04826 0,00013 0,05303 0,00013 0,05552 0,00013

Propane C3H8 3,3533 0,0003 3,5285 0, 0003 3,7712 0, 0003

Nitrogen N2 balance balance balance

Note: x – mole fraction, u(x) – absolute standard uncertainty

Purity tables for parent gases used for PSGM preparation for are given below.

Purity table for propane C3H8

Component Mole fraction, µmol/mol Standard uncertainty,

µmol/mol

C3H8 999677 13

C2H6 254 12

n-C4H10 10,1 0,5

iso-C4H10 8,0 0,4

N2 41 4

O2 10 1

Purity table for ethane C2H6


µmol/mol

C2H6 999996 0,4

CH4 0,31 0,03

C3H8 0,37 0,04

N2 2,2 0,4

O2 1,0 0,2

Purity table for propene C3H6


µmol/mol

C3H6 995568 118

C3H8 3831 115

C2H6 460 23

C2H4 127 6

CH4 3,2 0,2

N2 8,2 0,8

O2 2,4 0,5

24

Purity table for n-butane n-C4H10


µmol/mol

n-C4H10 995249 85

C3H8 240 12

C2H6 12,0 2,4

iso-C4H10 2450 74

iso-C5H12 17,0 0,8

neo-C5H12 680 34

C6H14 299 15

CH4 90 5

O2 43 4

N2 920 18

Purity table for iso-butane iso-C4H10


µmol/mol

iso-C4H10 994523 108

C3H8 2800 84

C2H6 495 25

n-C4H10 2100 63 1-C4H8 41 2

CH4 18,0 0,9

iso-C5H12 1,0 0,1

СO2 22 2,2

Purity table for iso-pentane iso-C5H12


µmol/mol

iso-C5H12 995390 220

n-C5H12 4400 220

neo-C5H12 210 10

Purity table for 1-butene 1-C4H8


µmol/mol

1-C4H8 990340 192

iso-C4H8 2120 64

iso-C4H10 1710 51

n-C4H10 5830 174

25

Purity table for nitrogen N2


µmol/mol

N2 999864 6

O2 3,0 0,3

CO2 0,10 0,03

Ar 132 6

H2O 1,3 0,1

Calibration and measurement

Gas chromatograph was calibrated according to ISO 6143 with the PSGMs (PSGM-1,

PSGM-2, PSGM-3). Analysis functions to determine the analytes content in the sample were taken

linear:

x(y) = b1y + b0

The gas mixture was analysed by comparison method according to ISO 6143. Four com-

parisons were made in reproducibility conditions (on different days).

Measurement sequence:

PSGM-1 х 4;

PSGM-2 х 4;

COOMET mixture (diluted with nitrogen) х 4;

PSGM-3 х 4.

Thus, each measurement included 4 replicates.

Sample handling

Gas mixtures were handled in accordance with ISO 16664.

The cylinders had been kept for 24 hrs at the room where the measurements were made.

The room was thermostatted at t = (20 ± 2) ºС.

Uncertainty evaluation

Composition of the gravimetrically prepared primary standard gas mixtures and its uncer-

tainty were calculated according to ISO 6142-1 and ISO 19229.

Results of analysis by comparison method and their uncertainty were calculated according

to ISO 6143, taking into account the uncertainties of the measuring system response, analysis

functions and primary standard gas mixtures. Calculations were made with B_LEAST software.

Uncertainties of components mole fractions normalised to 100 % of the hydrocarbons were

calculated according to ISO 6974-2.

For uncertainty evaluation the typical relative standard deviations in measurements by

comparison method were taken as they are more representative than smaller deviations obtained

in this comparison. Besides, the values of combined uncertainty were increased with regard to

possible influence of LPG sample evaporation procedure.

Participants: M. Rozhnov, D. Melnyk, S. Kisel, O. Levbarg, S. Shpilnyi, S. Yakubov

26

Report of VNIIM

КООМЕТ № 622/RU/13)

Supplementary comparison “С2-С5 components in mixtures of liquified hydrocar-

bons”

MEASUREMENT REPORT

I. Results of study

Laboratory:D.I. Mendeleyev Institute for Metrology (VNIIM)

Cylinder number: 1306

Measurement № 1

Date dd/mm/yy

Result (mol/mol) Standard deviation

(% relative)

Number of sub meas-urements,

n

Ethane 29/03/2017 2,0097 0,421 4

Propene 29/03/2017 8,8584 0,103 4

n-Butane 29/03/2017 10,1344 0,221 4

1-Butene 29/03/2017 2,9846 0,137 4

i-Butane 29/03/2017 4,0397 0,114 4

i-Pentane 29/03/2017 0,9985 0,463 4

Propane 29/03/2017 70,975 0,063 4

Measurement № 2

Date dd/mm/yy

Result (mol/mol) Standard deviation

(% relative)

Number of sub meas-urements

n

Ethane 02/04/2017 2,0329 0,293 7

Propene 02/04/2017 8,8912 0,067 7

n-Butane 02/04/2017 10,0562 0,151 7

1-Butene 02/04/2017 2,9751 0,114 7

i-Butane 02/04/2017 4,0216 0,126 7

i-Pentane 02/04/2017 0,9900 0,184 7

Propane 02/04/2017 71,032 0,041 7

Measurement № 3

Date

dd/mm/yy Result (mol/mol)

Standard deviation

(% relative)

Number of sub meas-

urements

n

Ethane 04/04/2017 2,0040 0,129 5

Propene 04/04/2017 8,8502 0,057 5

n-Butane 04/04/2017 10,1989 0,143 5

1-Butene 04/04/2017 2,9887 0,109 5

i-Butane 04/04/2017 4,0537 0,078 5

i-Pentane 04/04/2017 1,0003 0,280 5

Propane 04/04/2017 70,9043 0,043 5

27

Final results:

Component

Result

(assigned value),

cmol/mol

mol/mol

Coverage factor

Assigned expanded uncer-

tainty

cmol/mol

Ethane 2,016 2 0,018

Propene 8,867 2 0,028

n-Butane 10,130 2 0,050

1-Butene 2,983 2 0,012

i-Butane 4,038 2 0,016

i-Pentane 0,996 2 0,010

Propane 70,97 2 0,14

II. Description of study Instrument

The measurements were performed on GC system «Crystal-5000.2» (Chromatec, Russia) Data collection: Software “Chromatec Analytic 2.6” Detector: FID

Column: Restek Rt-Alumina, 30 m 0,53 mm Carrier gas: He Gas flow:10 ml/min Injected dose: 0.25 µl

Injector temperature: 50C

Temperature of the cooling zone of the injector: 10C

Detector temperature: 300C

Temperature program of the column thermostat: 40C – 5 min, 7C/min, 130C – 5 min. Calibration Standards

Preparation of LPG calibration mixtures (liquid) was carried out by gravimety in constant pressure cylinders (floating piston cylinders, 2 dm3). Every component was added directly from a conventional cylinder to a piston cylinder, except iso-pentane, which was transferred to the piston cylinder with a syringe. In the case of propane (major component) the cylinder was slightly heated during transferring in order to maintain enough vapour pressure. Before and after addition of each component the piston cylinder was weighed accurately on RAYMOR HCE-25G balance against a tare cylinder. After filling the piston cylinders were pressurized with He to 2.0 MPa. Purity analysis of the parent substances was carried out by GC- FID, TCD 1 Primary Reference Standard (PSM) was used for calibration. Composition of calibration standard is shown in the table 1. Table 1

Cylinder N 2316

Component

Amount of sub-stance fraction, cmol/mol

ugrav, cmol/mol (k=1)

Ethane 2,2647 0,0007

Propene 9,1447 0,0005

n-Butane 9,9547 0,0004

1-Butene 3,061 0,0005

i-Butane 4,0289 0,0004

i-Pentane 0,9890 0,0004

Propane 70,5443 0,0009

28

Purity data for parent gases is shown ithe tables 2-8 Table 2 - Purity data for ethane

Cylinder N4877


cmol/mol Standard uncertainty (k=1)

cmol/mol

ethane 99,99988 -

n-butane 0,00012 0,00001

Table 3- Purity data for propene

Cylinder N4142



cmol/mol

propene 99,97184 —

propane 0,0209 0,0008

nitrogen 0,0070 0,0007

i-butane 0,00026 0,00003

Table 4 - Purity data for n-butane

Cylinder N 3405


cmol/mol

Standard uncertainty (k=1)

cmol/mol

n-butane 99,97095 —

neo-pentane 0,0244 0,0007

i-butane 0,0031 0,0002

trans-2-butene

0,00088 0,00009

cis-2-butene 0,00037 0,00004

propane 0,00030 0,00003

Table 5 - Purity data for 1-butene

Cylinder N 4142


cmol/mol


cmol/mol

1-butene 99,4508 —

n-butane 0,243 0,006

i-butene (2-methylpro-pene)

0,124 0,008

i-butane 0,093 0,002

nitrogen 0,059 0,006

trans-2-butene 0,0103 0,0007

oxygen 0,010 0,001

propene 0,0058 0,0002

propane 0,0017 0,0002

29

1,3- butadiene 0,0014 0,0001

cis-2-butene 0,0010 0,0001

Table 6 - Purity data for i-butane

Cylinder N4874



cmol/mol

i-butane 99,97725 —

n-butane 0,012 0,001

propane 0,0102 0,0004

i-butene 0,00055 0,00006

Table 7- Purity data for i-pentane

Cylinder N 8027-1


cmol/mol


cmol/mol

i-pentane 99,6822 -

n-pentane 0,255 0,015

neo-pentane 0,043 0,004

toluene 0,0072 0,0007

n-heptane 0,0030 0,0003

n-hexane 0,0027 0,0003

1-hexene 0,0016 0,0002

2-methyl-1-butene 0,0016 0,0002

cyclohexane 0,00115 0,00001

1-pentene 0,00057 0,00006

n-butane 0,00051 0,00005

n-nonane 0,00047 0,00005

cyclopentane 0,00029 0,00003

3-methyl-1-butene 0,00020 0,00002

2,2-dimethylbutane 0,00018 0,00002

2-methyl-2-butene 0,00014 0,00001

benzene 0,00012 0,00001

n-octane 0,00010 0,00001

trans-2-pentene 0,00010 0,00001

2-methylpentane 0,00009 0,00001

3-methylpentane 0,000077 0,000008

30

Table 8 - Purity data for propane

Cylinder N 3889


cmol/mol


cmol/mol

propane 99,9957 —

n-butane 0,0029 0,0001

propene 0,00076 0,00006

ethane 0,00035 0,00004

i-butane 0,00025 0,00003

Instrument Calibration

Single point calibration method was used to determine components mole fraction in the LPG mixture to be investigated (mathematical model – у=ax). Measurement sequence was in the order: Calibration mixture - Comparison mixture - Calibration mixture Analysis results were normalised to 100 %.

Sample Handling

The cylinders had been kept for at least 24 hrs at room temperature (t = (20 ± 2) ºС) before

measurements.

The injection of the sample was carried out by sampling valve for liquefied gases, which enables to maintain single-phase state for mixtures of liquefied hydrocarbons with saturated vapor pressure higher than atmospheric. Pressure in the injection system is provided by pressure in a working chamber of the piston cylinder (2.0 MPa).

Uncertainty evaluation

Component

Measurement result, cmol/mol

ugrav

(purity+weighing),

cmol/mol

uanal

(between and within day

measurements), cmol/mol

u (combined standard

uncertainty), cmol/mol

U (expanded uncertainty,

k=2), cmol/mol

U0 (relative expanded

uncertainty), %

Ethane 2,016 0,0008 0,009 0,009 0,018 0,9

Propene 8,867 0,0006 0,014 0,014 0,028 0,3

n-Butane 10,130 0,0005 0,025 0,025 0,05 0,5

1-Butene 2,983 0,0004 0,006 0,006 0,012 0,4

i-Butane 4,038 0,0004 0,008 0,008 0,016 0,4

i-Pentane 0,996 0,0004 0,005 0,005 0,010 1,0

Propane 70,97 0,0010 0,072 0,072 0,14 0,20

supplementary comparison coomet.qm-s4 - bipm · 2019-07-09 · supplementary comparison...

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