mass metrology, april 2003mass metrology - susceptometer, june 2007 sartorius susceptometer - for...

Mass Metrology, April 2003Mass Metrology - Susceptometer, June 2007

Sartorius Susceptometer - for Precise Measurement of:Susceptibility and Magnetization of Weights

Benno GatzemeierMarket Manager Mass MetrologySartorius AG / Germany

June 2007


: Contents

: Introduction – Magnetic Properties of weights: Susceptometer Method: The Sartorius Susceptometer: Calibration Procedure and Factory Calibration: Long term stability of md

: Comparison Measurement


: Introduction

Influence Parameters in Mass Comparison :

• Air buoyancy• Contamination• Air draft• Object temperature• Magnetic properties

The golden rule in metrology is:Factors that influence the measurement are switched off, kept constant or considered.

• Magnetic properties


: Magnetic properties

The OIML R111 recommends to check the magnetic properties.

Standard Weights with a Susceptibility

MagnetN

S

Magnetic Forces

F

Susceptibility

Standard Weightwith Magnetization

Magnetic Forces

F

Magnetization

N

S

N

S


: The new OIML R111


: Susceptibility and Magnetization 0M (µT)

Susceptibility

0 a( ( ) )

zV

F dVz

H

M H

VHHz

µF

d2

0z VH

zMµ zz

d0

zF

H

zF

H - Hz

Magnetization 0M (µT)


: Recommended methods regarding the R111

E1 E2 F1 F25000kg1000kg S Susceptometer100kg S*50kg F fluxgate + permanent magnet

100g A attracting method50g Sp material specification10g2g1g1mg

F and A are prefered

OIML new R111 Table B.3(b)-SusceptibilityWeight

Sp SpSp

S / A S / AS S

S* / F / AS* / F / A

Sp

S* / F / A

S / F S / F / A S / F / A S / F / A


: Recommended methods regarding the R111

Permeability Indicator Gauss meter


: The Susceptometer Principe - Regarding the OIML R111

F1

F1 = - m1 * g

Susceptibility:

Fa =F1 + F2

2

=f (Fa...)

Magnetization:

Fb =F1 - F2

2

µ0MZ =f (Fb...)

F2

F2 = - m2 * g


: The Susceptometer Principe - Regarding the OIML R111

The R111 describes methods for the determination of the magnetic properties.

One of them is the Susceptometer principle.

A) Magnet

B) Weighing Pan

C) Bridge

D) Gauge blocks

E) Test Weight

F) Pedestal

F


: Sartorius Suszeptometer

The building guidance was the R111:

• A micro mass comparator • Internal magnet

• 5 different distances Z0

• Load plate for weights up to 50 kg • Software to compute the

formulae • Determination of:

- Susceptibility “ “- Magnetization “0M” (T)


: Vertical Distances Z0; Magnet <-> Weight

Magnet with md produces a maximum field H

Field H should not exceed initially:H 2000 A/m when testing class E1 H 800 A/m when testing class E2H 200 A/m for classes F1 and F2.

This is important to avoid permanent magnetization.Distance may be reduced only if the Susceptometer signal is too weak.

302 Zπ

mH d

Class Marking Colour of marking

Nominal Z0 in mm

Field H in A/m E1 E2 F1 F2

Z5 Green 43 200 Z4 Yellow 35 360 Z3 Yellow 27 800 Z2 Red 20 2000 Z1 Red 18 2700

Table 1: Initial values for testing class E1, E2, F1 and F2, magnetic (dipole) moment md 0.1 Am2


: Computation factors for Susceptibility and Magnetization:

• Weighing Result of the Magnet H

• Distance Z0 : Magnet <-> Weight H

• Geometry of the test weight S

• magnetic (dipole) moment md [Am2] S

• gravitational acceleration [m/s2] S

• Local magnet field BEZ –48-60 [µT] S

To measure the Magnetization, we have to rotate the magnet!H


3

2

1

214

1

o3

2

o

2o4

1

oa

1

31

1

31

1

)Z

R(

)Z/R(

Z

Z

)Z

R(

)Z/R(

Z

ZI

w

w

w

w

: Calculation of the Magnetic properties

232

o1

o

3

o

1

2

o

232

o

2

ob

11

2/

w

w

/

w

w

Z/Z

Z/R

Z

Z/

Z

R

Z

R

Z

R

I

a

a max a0.4

F

I F F

40

20

max 64

3

Z

m

π

μF d

221

a

FFF

221

b

FFF

EZb

0

d

b0 23.01

4

BI

Z

mF

Mµ Z

Calculation of the susceptibility

Calculation of the Magnetization


: The vertical rotation mechanics of the magnet

• Changes the orientation of the magnet

• Parts:Magnet Pedestal GearKnob


: Application Software

• Easy operating• Step by step guide through the measurement procedure• Initial distance is proposed• Results via a serial connection• Calculations, report and export• Recalibrating the necessary constants• Default parameters and user defined configurations• Shape description, OIML knob weights predefined• Export and import function for the sharp of the weights


: 1. Select weighing geometry


: Own cylinder - Geometry of the test weight


: 2. Input parameter


: 3. Remove test weight


: 4 Adjust vertical position Z2


: 5. Adjust test magnet to position “N”


: 6. Tare balance : 7. Place test weight


: 8. Determine measured value m1 for Z4 : 9. Remove test weight


: 10. Adjust test magnet to position “S”


: 11. Tare balance : 12. Load test weight


: 13. Determine measured value m2 for Z5 : 14. Remove test weight


: Push result button


: Technical specifications Sartorius Susceptometer

• Base area 338 x 286 mm• Height 249 mm• Maximum load 50 kg• Dipole moment of the magnet m ~ 0.1 Am2

• Geometry ratio of the magnet h/d = 0.87• Height Z0 adjustable in fixed steps Z1=18 / Z2=20 / Z3=27 / Z4=35

/ Z5=43mm• Field strength 2700 / 2000 / 800 / 360 / 200

A/m• Readability of the Mass Comparator 10 µg or 1 µg• Reverse gear for magnet external rotary knob with N-S marking


Calibration, check of the Susceptometer

1. Calibration of the Mass comparator (10 g)

2. Using a Susceptibility Referencewith certificate of the susceptibility

3. Measure the Susceptibility Reference on the Sartorius Susceptometer

4. Compare the result of the Susceptometer with the PTB-certificate.

5. The difference has to be less than 10%


Factory calibration

• We use a 1 kg stainless steel susceptibility standard (=0.004069)

• Additional information is used as check for the factory calibration:

– Value of the vertical distance Z0 from the mechanical adjustments in the manufacturing

– We use always the same three additional magnets.historical data (md )


1. Calibration of the mass comparatoruses a 10 g weight

2. Calibration of the dipole moment md, uses 3 additional magnets and measure the forces between each pair of magnets6 equations and 4 unknown dipole moments

3. Calibration of the distance Z0,uses a susceptibility standard at known

Calibration procedure / Adjustment

F1-2

F1-4 F2-3

F1-3

F3-4

F2-4

PTB


Comparison Measurement

Our references Susceptibilities4 x NPL Standards 1 x PTB Standard

Question: Calibration with susceptibility standard : =0.00401 Application range : 0 < 1


Our Susceptibility standards

PTB2419

NPL1005

NPL 1024

NPL11 NPL16

0.00401 0.0055 0.02657

0.1173 0.693

U() k=2 0.00004 0.00005 0.000205

0.00056 0.0034

H in kA/m 5.0 2.7 2.0 0.8 0.2

Diameter in mm

59 40 40 40 25

Height in mm

45 27 25 27 25

Position Z1 Z1 Z2 Z3 Z5


Comparison Measurement

Calibration with

/

PTB2419

0.00401

NPL10050.0055

NPL 10240.02657

NPL110.1173

NPL160.693

PTB2419 0.0 % -3.3 % -4.8% -5.2 % -5.8 %

NPL1005 3.1% 0.0 % -1.9 % -2.9 % -4.0 %

NPL1024 5.1 % 2.1% 0.0 % -1.5 % -2.8 %

NPL11 7.1 % 4.3 % 1.9% 0.0 % -1.6%

NPL16 10.0 % 7.3 % 4.6 % 2.1 % 0.0 %

Cathetometer

10.7 % 8.0 % 5.3 % 2.6 % 0.4 %


Susceptibility Reference PTB 2419

0,00390

0,00395

0,00400

0,00405

0,00410

0,00415

2002 2003 2004 2005

Long term stability of our reference Susceptibility

The change of the Susceptibility is in the range of the uncertainty and less than 2 %


Long term stability of our reference magnets md


Thank you for your attention

Benno GatzemeierMass Metrology

Sartorius AG / Germany

mass metrology, april 2003mass metrology - susceptometer, june 2007 sartorius susceptometer - for...

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