Mass Metrology, April 2003Mass Metrology - Susceptometer, June 2007 Sartorius Susceptometer - for Precise Measurement of: Susceptibility and Magnetization of Weights Benno Gatzemeier Market Manager Mass Metrology Sartorius AG / Germany June 2007

Mass Metrology, April 2003Mass Metrology - Susceptometer, June 2007 : Contents : Introduction – Magnetic Properties of weights : Susceptometer Method : The Sartorius Susceptometer : Calibration Procedure and Factory Calibration : Long term stability of m d : Comparison Measurement

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

Mass Metrology, April 2003Mass Metrology - Susceptometer, June 2007 : Magnetic properties The OIML R111 recommends to check the magnetic properties. Standard Weights with a Susceptibility Magnet N S Magnetic ForcesF Susceptibility Standard Weight with Magnetization Magnetic ForcesF Magnetization N S N S

Mass Metrology, April 2003Mass Metrology - Susceptometer, June 2007 : The new OIML R111

Mass Metrology, April 2003Mass Metrology - Susceptometer, June 2007 : Susceptibility  and Magnetization  0 M (µT) Susceptibility  H H - H z Magnetization  0 M ( µ T)

Mass Metrology, April 2003Mass Metrology - Susceptometer, June 2007 : Recommended methods regarding the R111

Mass Metrology, April 2003Mass Metrology - Susceptometer, June 2007 : Recommended methods regarding the R111 Permeability Indicator Gauss meter

Mass Metrology, April 2003Mass Metrology - Susceptometer, June 2007 : The Susceptometer Principe - Regarding the OIML R111 F1F1 F 1 = -  m 1 * g Susceptibility: F a = F 1 + F 2 2  =f (F a...) Magnetization: F b = F 1 - F 2 2 µ 0 M Z =f (F b...) F2F2 F 2 = -  m 2 * g

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

Mass Metrology, April 2003Mass Metrology - Susceptometer, June 2007 : Sartorius Suszeptometer The building guidance was the R111: A micro mass comparator Internal magnet 5 different distances Z 0 Load plate for weights up to 50 kg Software to compute the formulae Determination of: - Susceptibility “  “ - Magnetization “  0 M ” (  T)

Mass Metrology, April 2003Mass Metrology - Susceptometer, June 2007 : Limits for magnetic properties - Regarding the OIML R111 Table 3 - Maximum permanent magnetization,  0 M (µT) Table 4 - Maximum susceptibility,  Weight ClassE1E1 E2E2 F1F1 F2F2 M1M1 M2M2 M3M3 Maximum Magnetization, µ 0 M (µT) Weight classE1E1 E2E2 F1F1 F2F2 m  1 g g  m  10 g g  m

Mass Metrology, April 2003Mass Metrology - Susceptometer, June 2007 : Vertical Distances Z 0 ; Magnet Weight Magnet with m d 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 E2 H  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. Table 1: Initial values for testing class E1, E2, F1 and F2, magnetic (dipole) moment m d  0.1 Am 2

Mass Metrology, April 2003Mass Metrology - Susceptometer, June 2007 : Computation factors for Susceptibility and Magnetization: Weighing Result of the MagnetH Distance Z 0 : Magnet WeightH Geometry of the test weight S magnetic (dipole) moment m d [Am 2 ]S gravitational acceleration [m/s 2 ]S Local magnet field B EZ – [ µ T]S To measure the Magnetization, we have to rotate the magnet!H

Mass Metrology, April 2003Mass Metrology - Susceptometer, June 2007 : Calculation of the Magnetic properties Calculation of the susceptibility Calculation of the Magnetization

Mass Metrology, April 2003Mass Metrology - Susceptometer, June 2007 : The vertical rotation mechanics of the magnet Changes the orientation of the magnet Parts: Magnet Pedestal Gear Knob

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

Mass Metrology, April 2003Mass Metrology - Susceptometer, June 2007 : 1. Select weighing geometry

Mass Metrology, April 2003Mass Metrology - Susceptometer, June 2007 : Own cylinder - Geometry of the test weight

Mass Metrology, April 2003Mass Metrology - Susceptometer, June 2007 : 2. Input parameter

Mass Metrology, April 2003Mass Metrology - Susceptometer, June 2007 : 3. Remove test weight

Mass Metrology, April 2003Mass Metrology - Susceptometer, June 2007 : 4 Adjust vertical position Z2

Mass Metrology, April 2003Mass Metrology - Susceptometer, June 2007 : 5. Adjust test magnet to position “N”

Mass Metrology, April 2003Mass Metrology - Susceptometer, June 2007 : 6. Tare balance : 7. Place test weight

Mass Metrology, April 2003Mass Metrology - Susceptometer, June 2007 : 8. Determine measured value m1 for Z4: 9. Remove test weight

Mass Metrology, April 2003Mass Metrology - Susceptometer, June 2007 : 10. Adjust test magnet to position “S”

Mass Metrology, April 2003Mass Metrology - Susceptometer, June 2007 : 11. Tare balance: 12. Load test weight

Mass Metrology, April 2003Mass Metrology - Susceptometer, June 2007 : 13. Determine measured value m2 for Z5: 14. Remove test weight

Mass Metrology, April 2003Mass Metrology - Susceptometer, June 2007 : Push result button

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

Mass Metrology, April 2003Mass Metrology - Susceptometer, June 2007 : Technical specifications Sartorius Susceptometer Base area338 x 286 mm Height249 mm Maximum load50 kg Dipole moment of the magnetm ~ 0.1 Am 2 Geometry ratio of the magneth/d = 0.87 Height Z0 adjustable in fixed stepsZ1=18 / Z2=20 / Z3=27 / Z4=35 / Z5=43mm Field strength 2700 / 2000 / 800 / 360 / 200 A/m Readability of the Mass Comparator10 µg or 1 µg Reverse gear for magnetexternal rotary knob with N-S marking

Mass Metrology, April 2003Mass Metrology - Susceptometer, June 2007 Calibration, check of the Susceptometer 1. Calibration of the Mass comparator (10 g) 2. Using a Susceptibility Reference with 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%

Mass Metrology, April 2003Mass Metrology - Susceptometer, June 2007 Factory calibration We use a 1 kg stainless steel susceptibility standard (  = ) Additional information is used as check for the factory calibration: – Value of the vertical distance Z 0 from the mechanical adjustments in the manufacturing – We use always the same three additional magnets. historical data (m d )

Mass Metrology, April 2003Mass Metrology - Susceptometer, June Calibration of the mass comparator uses a 10 g weight 2. Calibration of the dipole moment m d, uses 3 additional magnets and measure the forces between each pair of magnets 6 equations and 4 unknown dipole moments 3. Calibration of the distance Z 0, uses a susceptibility standard at known  Calibration procedure / Adjustment F 1-2 F 1-4 F 2-3 F 1-3 F 3-4 F 2-4 PTB

Mass Metrology, April 2003Mass Metrology - Susceptometer, June 2007 Comparison Measurement Our references Susceptibilities 4 x NPL Standards1 x PTB Standard Question: Calibration with susceptibility standard :  = Application range : 0 <   1

Mass Metrology, April 2003Mass Metrology - Susceptometer, June 2007 Our Susceptibility standards PTB2419NPL1005NPL 1024NPL11NPL16  U(  ) k= H in kA/m Diameter in mm Height in mm PositionZ1 Z2Z3Z5

Mass Metrology, April 2003Mass Metrology - Susceptometer, June 2007 Comparison Measurement Calibration with  /  PTB NPL NPL NPL NPL PTB %-3.3 % -4.8% -5.2 %-5.8 % NPL %0.0 %-1.9 %-2.9 %-4.0 % NPL %2.1%0.0 %-1.5 %-2.8 % NPL117.1 %4.3 %1.9%0.0 %-1.6% NPL %7.3 %4.6 %2.1 %0.0 % Cathetometer10.7 %8.0 %5.3 %2.6 %0.4 %

Mass Metrology, April 2003Mass Metrology - Susceptometer, June 2007 Long term stability of our reference Susceptibility  The change of the Susceptibility is in the range of the uncertainty and less than 2 %

Mass Metrology, April 2003Mass Metrology - Susceptometer, June 2007 Long term stability of our reference magnets m d

Mass Metrology, April 2003Mass Metrology - Susceptometer, June 2007 Thank you for your attention Benno Gatzemeier Mass Metrology Sartorius AG / Germany