Sartorius Volume Comparator VD1005 A new Method for highly accurate Density Determination Benno Gatzemeier, Market Manager Mass Metrology, Sartorius AG / Germany, August 2008 | NCSL International Workshop and Symposium

Agenda 1.A Successful Cooperation 2.The Measuring Principle of VD The Measuring Steps according to OIML R111 4.VD1005 System Design Measuring Cabinet Measuring Mechanics The Double Load Alternator The Mass Comparator of the VD1005 The Hanging Weighing Pan Thermostatic Liquid Tank Control Unit 5.Included Software 6.Summary and Results

2008 NCSL International Workshop and Symposium page 3 A Successful Cooperation: Bundesamt für Eich- und Vermessungswesen Österreich Federal Office of Metrology and Surveying Austria Institut für Fertigungstechnik (IFT) Österreich Institute for Manufacturing Technology of the Technical University of Vienna Austria

2008 NCSL International Workshop and Symposium page 4 The Measuring Principle of VD1005: The basic design is based on OIML method A2 (hydrostatic comparison) The second load alternator in air is new F g (m rl )+ F g (m r1 ) ~ F g (m tl ) + F g (m r2 )~ F g (1 kg) Only one density reference is necessary Direct comparison of the primary density reference to any weight (1 g – 1 kg) Density method A1 and A3 is also possible Fully automatic density determination of the liquid and the air is integrated (using Si-spheres) see OIML R111 page 46 Weight holder Suspension wire Substitution weights

2008 NCSL International Workshop and Symposium page 5 The Measuring Steps according to Method A2, OIML R111  Determines the density of 1. The liquid with the volume reference (Si-spheres, t, m) 2. The air with a climate station (t, p, hr)  Measures the mass of the 1. Test weight in air 2. Reference weight in air 3. Test weight (B) in liquid 4. Reference weight (A) in liquid

2008 NCSL International Workshop and Symposium page 6 VD1005 System Design: Contents of the Volume Comparator: 1.The control system: PC with monitor and keyboard Mass comparator electronic box Temperature measuring bridge Load alternator drive control 2.The measuring cabinet: Mass comparator Load alternator Liquid tank Sensors (t air, t liquit p, hr)

2008 NCSL International Workshop and Symposium page 7 Measuring Cabinet: 1kg mass comparator V1005 Motors and gears for the load alternator and lifting system Load alternator in air with 9 positions (for substitution weights) Lifting system Isolated enclosure Load alternator in liquid with 9 positions (for test and reference weights) Thermostated double-walled liquid tank

2008 NCSL International Workshop and Symposium page 8 Measuring Mechanics: Magazine changer Load alternator in air for substitution weights 1 kg mass comparator Suspension system Locking device of both weighing pans Load alternator in liquid for reference and test weights Lifting system Silicon sphere density reference Test weight Weighing pan in air Weighing pan in liquid Overload protection

2008 NCSL International Workshop and Symposium page 9 The Double Load Alternator: 2 x 9 positions (air/liquid) Direct handling of weights, weighing groups Handling of Si-spheres up to 1 kg Direct loading of weights in range of 1 g – 1 kg Seawater resistance aluminum Safety lifting system

2008 NCSL International Workshop and Symposium page 10 The Mass Comparator of the VD1005: Weighing range:1 kg Readability:10 µg Typical repeatability:20 µg Capacity:1125 g Weighing range, electronic:350 g Monolithic weighing cell

2008 NCSL International Workshop and Symposium page 11 The Hanging Weighing Pan: Rubber surface protection Self centering hanging pan 2 hanging weighing pans, one pan in air, one in liquid Space between the tines < 0.3 mm Automatic weighing pan positioning system

2008 NCSL International Workshop and Symposium page 12 Thermostatic Liquid Tank: Tank with double-walled glass for clean water or other liquids Temperature controlled by thermostat Internal measuring cell (glass cylinder) 2 temperature sensors (1 mK) in liquid 9 position load alternator Lifting system Self centering hanging weighing pan Measurement cell fully in thermostated liquid Temperature stability < 0.01 K

2008 NCSL International Workshop and Symposium page 13 Control Unit: Industrial PC + monitor + key board Temperature measuring bridge (for 2 liquid temperature sensors) Climate station to measure the air density (t, p, hr) Mass comparator electronic box Control electronics for the load alternator Interfaces (USB, LAN, RS232)

2008 NCSL International Workshop and Symposium page 14 Included Software:  Windows ® based software  Control and calculation  Data based structure  Import and export function

2008 NCSL International Workshop and Symposium page 15 Analysis of the Measuring Results Result of a volume determination: Pyrex sphere; mass approx. 119 g, volume approx. 97 cm³  The result shows: mass, volume and density,  The documentation of all inputs and environment parameters

2008 NCSL International Workshop and Symposium page 16 Volume Comparison between BEV – OMH - PTB

2008 NCSL International Workshop and Symposium page 17 Summary and Results:  Fully PC controlled complete solution  Density application range1 g – 1 kg  Direct handling of weights, weighing groups and Si-spheres  2 x load alternators (in air and liquid)  2 x 9 magazine places  Volume uncertainty < 0.2 mm³  Density uncertainty< 0.6 kg/m³  Uncertainty, weighing cell< 0.04 mg  ABBA cycle time< 4 min

2008 NCSL International Workshop and Symposium page 18 Thank you for your attention ! Benno Gatzemeier Market Manager Mass Metrology Sartorius AG / Germany References: [1] International Recommendation OIML R111 [2] Mr. Buchner (BEV, Austria), poster session at the Metrology Conference in France 2007, [3] Mr. Buchner (BEV, Austria), WeighAhead No.9, Sartorius application magazine