MASS LABORATORY
       
      Quantity
      The Weight denotes a quantity of the same natures: the weight of a body is the standard weight of a body is the product of its mass and the standard acceleration due to gravity.
      Unit
      The basic unit kilogram (kg) is the unit of mass. It is equal to the Mass of the International prototype of the kilogram which kept at the BIPM. Other units used are gram (g = 10-3 kg), miligram (mg = 10-6 kg) and ton (t = 1000 kg).
      Tasks of the laboratory
      The main tasks of the Laboratory are research and development to the realisation and dissemination of the unit of mass, the kilogram.
      International comparisons
      The SMU Ptlr standards are calibrated in BIPM Sevres during the 20 years period.
1998 - Comparison measurement within PHARE Programme (under command of NPL, GB) of the SMU mass standards (5 kg, 1 kg, 200 g, 50 g, 10 g).
1998 - CCM 5 Key Comparison BIPM for calibration of mass scale.
2000 - COOMET Comparison measurement, Project No.127 of compare of the two 1 kg standards value.
  Available metrological services
      Calibration of sets of weights: accuracy class E1 (range 1 mg - 1 kg), accuracy class E2 (range 1 mg - 50 kg).
Verification and calibration of fine balances of I. and II. accuracy classes in the range up to 50 kg and up to 1000 kg.
    Methods of measurement:
      The SMU has two Pltr mass standards, which are verified in BIPM Serves, compared to the international kilogram prototype copies. At the SMU Mass Laboratory the mass unit value is transfered from Ptlr standards to stainless steel mass standards of 1 kg (direct comparison method at balance Mettler AT 1006) and the mass scale is calibrated in the range from 1 mg - 100 kg.
During the verification of standards and working weights the expanded uncertainties of determination of weight mass are lower than 1/3 of maximum permissible errors by OIML R111.
Expanded uncertainty is expressed as double value of combined standard uncertainty defined in GUM. At the calibration of balances of I. class accuracy (analytical balances) it is possible to reach uncertainties of mass determination of built in weights equal to E2 class accuracy of working weights.
       
  Supplementary activities
      Evaluation of pattern approval of balances of I., II. and partly of III. accuracy classes uo to 1000 kg. Providing of production and verification of mass standards and working weights of E2 accuracy class and production of standard balances of hightest accuracy classes up to 1000 kg (mechanical knives balances and electro-magnetic force compensation balances with flexure strips).
       
  Instruments in use
      Automatic weighting device for calibration of sets of weights range 1 kg to 100 g.
 SMU standard mechanical balance 1 kg to 100 g - constant load arrestment system.

 The National Mass Standard consists of 1 kg Ptlr Mass standards (compared to the international standards in BIPM Serves) and electronic mass comparator Mettler AT 1006 with device for air density determination (Klimet A 30). For the calibration of weights are used the following reference Mass standards and balances:
- 1 kg secondary mass standards;- sets of working standards from 1 g - 500 g made of steel with density of 8 g·cm-3 (E1-OIML);
- Pt standards from 1 mg - 500 mg and sets of steel standards from 1 g - 10 kg (E2-OIML);
- the Mass standards sets up to 50 kg and the total load of 1000 kg (20 pieces of 50 kg) of stainless non-magnetic steel;
      - SMU mechanical standard balances from 1 kg - 10 kg (s = 0.05 mg), these standard balances works by method without separation of knives from bearings and with constant load at the weights exchange, simutaneous calibration of two weight sets;
- the standard comparator balances of 100 kg ( s = 1 mg, toploader type with built - in weights, Cu-Be flexures, ± 100 g of electromagnetic force compensation and lifting/loading controlled mechanism);- computer controlled automatic weighting devices for calibration of sets of weights: ranges - from 1 kg to 100 g (with Mettler AT 1005), from 100 g to 1 g (with Mettler AT 106), from 1 kg to 10 kg (with Sartorius CC 10000), from 1 g to 1 mg (with sartorius CC 20).
      Each device has a vertical pan below the balance. The pan is for 6 weights individually loaded in necessary combination (by calibration schemes).
     
Contact
Dr. Robert Spurný Dr. Jana Bičárova Mr. Vladimír Tibenský
phone: + 421 2 60294 350 phone: + 421 2 60294 350 phone: + 421 2 60294 336
e-mail: spurny@smu.gov.sk e-mail: spurny@smu.gov.sk e-mail: tibensky@smu.gov.sk