Differential Pressure Comparison From 5 Pa to 500 Pa With a Liquid Column Manometer Between CENAM...

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Differential pressure comparison from 5 Pa to 500 Pa with aliquid column manometer between CENAM (Mexico)and INTI – Fisica y Metrologia (Argentina)

Jorge Torres-Guzman a ,⇑ , Juan Forastieri ba Centro Nacional de Metrología, km 4.5 carr. a Los Cués, El Marques Querétaro, Mexicob Instituto Nacional de Tecnología Industrial, Av. General Paz y Albarellos, San Martín Pcia, de Buenos Aires, Argentina

a r t i c l e i n f o

Article history:Available online 11 August 2013

Keywords:Differential pressureComparison

a b s t r a c t

A differential pressure comparison was performed between CENAM (Mexico) and INTI(Argentina) by means of a liquid column manometer. The measuring range was 5–500 Pa. CENAM calibrated the transfer standard at the beginning and at the end of thecomparison. The transfer standard used was a Dwyer liquid column manometer modelMicrotector with an accuracy class of 0.013% of the reading. The compared pressure pointswere (5, 75, 125, 200, 250, 300, 350, 400, 450, 500) Pa. The uncertainty sources to be eval-uated included at least the following: (a) Uncertainty due to the standard used by the lab-oratory; (b) Uncertainty due to repeatability; (c) Uncertainty due to resolution; (d)Uncertainty due to hysteresis; (e) Uncertainty due to zero drift. The criteria used to com-pare the results obtained were the normalized error equation ( E n). The results obtained bythe laboratories were compatible according to the criteria | E n| 6 1.

2013 Published by Elsevier Ltd.

1. Introduction

A differential pressure comparison has been carried outbetween the National Metrology laboratories form Mexico(CENAM) and Argentina (INTI – Física y Metrología) bymeans of a liquid column manometer. The measuringrange was from 5 Pa to 500 Pa; the comparison took placefrom October 2010 to February 2011. CENAM calibrated

the transfer standard at the beginning and at the end of the comparison, in accordance to international references[1–3] . The transfer standard used for this comparisonwas a Dwyer liquid column manometer model Microtectorwith an accuracy class of 0.013% of the reading. Eleven dif-ferential pressure points were compared. The comparisonis registered at SIM as supplementary comparisonSIM.M.P-S6.

2. Comparison conditions

2.1. Transfer standard (TS)

The transfer standard (TS) used for the comparison isshown in Fig. 1 and its general specications in Table 1 .

2.2. Procedure

The procedure used for the comparison consisted of the TS calibration by measuring 11 differential pressurepoints distributed on the instrument range (5, 75, 125,200, 250, 300, 350, 400, 450, 500) Pa. Six series of mea-surements were taken, both ascending and descendingorder. The procedure was the ‘‘SIM technical protocol,supplementary comparison SIM.M.P-S6 in low pressure50–500 Pa’’ send for registration and approval to theSIM MWG7 (SIM working group 7, mass and relatedquantities).

0263-2241/$ - see front matter 2013 Published by Elsevier Ltd.http://dx.doi.org/10.1016/j.measurement.2013.06.023

⇑ Corresponding author. Tel.: +52 442 2110572; fax: +52 442 2110578.E-mail address: [email protected] (J. Torres-Guzman).

Measurement 46 (2013) 4328–4331

Contents lists available at ScienceDirect

Measurement

j o u r n a l h o m e p a g e : w w w. e l s e v i e r. c o m / l o c a t e/ m e a s u r e m e n t

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2.3. Laboratories standards used

CENAM used a measurement system consisting on 2high accuracy pressure balances (piston cylinder assem-

blies of 50 mm diameter). One pressure balance maintainsthe static pressure and the second balance generates thedifferential pressure. Details of the system used are shownin Table 2 . Fig. 2 shows a photo of the system.

Details of INTI ´s reference standard is shown in Table 3 .Fig. 3 shows a photo of the standard.

3. TS characterization

Table 4 shows the two CENAM ´ s calibrations. Results foreach measured pressure included error and uncertainty.Fig. 4 shows a graph of the measurements presented inTable 4 .

Fig. 1. Transfer standard, liquid column manometer.

Table 1

Transfer standard general specications.

Instrument Liquid column manometer

Make DwyerModel M1430Serial number S48HRange 1–50 mm H 2OAccuracy class 0.013% of the reading

Table 2

CENAM’s reference differential pressure measurement system.Piston – cylinder(differential)

Piston – cylinder(reference)

Manufacturer DH Instruments DH InstrumentsModel PC-7607-5 PC-7607-5Serial number 231 216 A

Fig. 2. CENAM’s reference system.

Table 3

INTI’s reference standard.

Manufacturer Junkalor, Dessau, D

Type Diving Bell

Fig. 3. INTI’s calibration standard.

Table 4

Transfer standard uncertainty and error of the 2 calibrations made byCENAM.

Differentialpressure(Pa)

TS error1st cal(Pa)

TS error2nd cal(Pa)

TS U (k = 2)1st cal (Pa)

TS U (k = 2)2nd cal (Pa)

50 0.04 0.05 ±0.19 ±0.16100 0.05 0.03 ±0.13 ±0.13125 0.04 0.02 ±0.13 ±0.13150 0.02 0.01 ±0.13 ±0.13200 0.18 0.14 ±0.16 ±0.14250 0.17 0.11 ±0.16 ±0.13300 0.16 0.13 ±0.14 ±0.14350 0.09 0.07 ±0.18 ±0.18400 0.04 0.04 ±0.13 ±0.12450 0.08 0.06 ±0.12 ±0.14500 0.03 0.02 ±0.13 ±0.16

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From the calibrations made to the TS and presented inTable 4 and Fig. 4 , it is considered that the TS is adequatefor the purposes of this comparison and the drift is of nosignicance for the level of uncertainties compared.

4. Laboratories calibration results

The calibration results made by the laboratories are in-cluded here. CENAM ´ s data used for this comparison is theaverage of the two calibrations performed.

Table 5 shows the data used as CENAM ´ s TS calibration(the average of the two calibrations performed). In Fig. 5the results are presented in a graph including errors anduncertainties for each differential pressure of the rangecompared.

Table 6 shows the results of the TS calibration made byINTI – Física y Metrología.

Fig. 6 shows INTI ´s results. The graph includes errors anduncertainties for each measured pressure.

5. Comparison results

The calibration results from CENAM and INTI are shownin Fig. 7 . The graph shows the results of both laboratoriesfor each pressure point and includes the associated uncer-tainty in the range, 50–500 Pa.

5.1. Uncertainty and comparison criteria

The uncertainty sources to be evaluated included atleast the following: (a) Uncertainty due to the standardused by the laboratory; (b) Uncertainty due to repeatabil-

Table 5

Transfer standard error and U used by CENAM.

TS pressure TS error U (k = 2)

50 0.04 ±0.17100 0.04 ±0.13125 0.03 ±0.13150 0.01 ±0.13200 0.16 ±0.15250 0.14 ±0.14300 0.14 ±0.14350 0.08 ±0.18400 0.04 ±0.12450 0.07 ±0.13

500 0.02 ±0.14

Table 6

INTÍs transfer standard error and uncertainty.

TS pressure TS error U (k = 2)

50 0.00 ±0.30100 0.03 ±0.30125 0.06 ±0.30

150 0.10 ±0.30200 0.13 ±0.30250 0.09 ±0.30300 0.13 ±0.30350 0.02 ±0.30400 0.02 ±0.30450 0.07 ±0.30500 0.00 ±0.30

Fig. 6. Transfer standard calibration results from INTI.

Fig. 4. Transfer standard uncertainty and error of the 2 calibrations madeby CENAM.

Fig. 5. TS error and U used by CENAM.

Fig. 7. Transfer standard error and uncertainty ( k = 2) from the calibra-tions made by CENAM and INTI.

4330 J. Torres-Guzman, J. Forastieri / Measurement 46 (2013) 4328–4331

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ity; (c) Uncertainty due to resolution; (d) Uncertainty dueto hysteresis; and (e) Uncertainty due to zero drift.

The criteria used to compare the results obtained by thetwo laboratories were the normalized error equation ( E n),which is calculated from Eq. (1) .

E n ¼ x INTI xCENAM

ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi U 2INTI þ U 2CENAM q ð1 Þ

where xCENAM is the error calculated by CENAM, xINTI is theerror calculated by INTI, U CENAM is the expanded uncer-tainty ( k = 2) estimated by CENAM, and U INTI is theexpanded uncertainty ( k = 2) estimated by INTI.

Table 7 shows the E n results between the twolaboratories.

6. Conclusions

The calibration of the differential pressure transferstandard obtained by CENAM (Mexico) and INTI (Argen-tina) in the range from 50 Pa to 500 Pa clearly shows thatthere is compatibility between the two laboratories. Theresults of the comparison were | E n | < 1 in all pressure

points compared, which meets the criteria of compatibility.

Acknowledgements

CENAM and INTI – Física y Metrología want to thanktheir pressure laboratories people for their involvementand collaboration in this comparison.

References

[1] A. Calcatelli, F. Arrhen, M. Bergoglio, J. Greenwood, R. Kangi, K. Jousten, J.-C. Legras, M. Rantanen, J. Verbeek, C. Matilla, D. Szaulich,Results of the regional key comparison EUROMET.M.P-K1.a in thepressure range from 0.1 Pa to 1000Pa, Metrologia 42 (Tech. Suppl.)(2005) 07004 .

[2] J.C. Torres-Guzman, S. Ruiz, P. Olvera, Ma. Nieves Medina, Differentialpressure comparison from 20 Pa to 3 500 Pa between CEM-Spain andCENAM-Mexico, Memories of XIX IMEKO World CongressFundamental an Applied Metrology, Lisbon, Portugal.

[3] J.C. Torres-Guzman, S. Zúñiga, P. Olvera, Caracterización de unmanómetro diferencial digital usado como patrón de transferencia a3.5 kPa [Characterization of a digital differential manometer used astransfer standard at 3.5 kPa], in: Simposio de Metrologia 2008,Queretaro, Mexico, October 2008.

Table 7

Normalized error between the laboratories.

Differential pressure(Pa)

Normalizederror

50 0.14100 0.03125 0.06150 0.26

200 0.10250 0.69300 0.04350 0.17400 0.18450 0.43500 0.07

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Differential Pressure Comparison From 5 Pa to 500 Pa With a Liquid Column Manometer Between CENAM...

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