E1 CLASS CALIBRATION WEIGHTS

1. General Description

E1 Class Calibration Weights are ultra-high accuracy mass standards used as reference standards for calibration of E2 and F1 class weights and ultra-precision analytical balances. These weights are intended for use in controlled laboratory environments.

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2. Standards & Metrological Compliance

• Accuracy Class: E1

• International Standard: OIML R-111-1

• Calibration Standard: ISO/IEC 17025

• Traceability:

  • Traceable to National Physical Laboratory (NPL), India or equivalent

  • SI unit of mass (kilogram)

• Calibration Requirement: Mandatory NABL accredited calibration

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3. Nominal Weight Range

• 1 mg to 500 mg (foil / wire type)

• 1 g to 1 kg (solid cylindrical type)
  (Higher capacities available on request, subject to feasibility)

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4. Metrological Characteristics (Typical)

(As per OIML R-111; actual uncertainty stated in NABL certificate)

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5. Material Specifications

• Material: Special non-magnetic austenitic stainless steel

• Alloy: High-purity SS (vacuum melted)

• Density: (8000 ± 10) kg/m³

• Magnetic Susceptibility: ≤ 0.005

• Residual Magnetism: ≤ 0.5 µT

• Surface Reactivity: Extremely low adsorption

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6. Construction & Surface Finish

• Design:

  • Cylindrical with adjusting cavity (g to kg)

  • Foil / wire type (mg range)

• Manufacturing: Ultra-precision CNC machining

• Surface Finish:

  • Super-polished mirror finish

  • Surface roughness Ra ≤ 0.1 µm

• Edge Geometry: Optimized to minimize air turbulence

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7. Dimensional & Thermal Stability

• Coefficient of Thermal Expansion:
  ~16 × 10⁻⁶ /°C

• Dimensional Stability:
  Extremely high, minimal mass drift

• Long-Term Stability:
  < 1/20 of MPE per year under controlled storage

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8. Air Buoyancy & Density Correction

• Reference Air Density: 1.2 kg/m³

• Air Buoyancy Correction: Mandatory

• Density Value: Individually measured & stated on certificate

• Suitability: Ideal for mass comparator calibration

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9. Environmental Reference Conditions (Calibration)

• Temperature: 20.0 °C ± 0.5 °C

• Relative Humidity: 45 % – 55 % RH

• Atmospheric Pressure: 950 – 1050 hPa

• Vibration: Negligible (metrology lab conditions)

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10. Handling & Usage Requirements

• Use powder-free gloves or tweezers only

• Never touch with bare hands

• Allow thermal stabilization (minimum 2–4 hours)

• Use in draft-free, temperature-controlled environment

• Clean only with approved laboratory methods

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11. Storage & Packaging

• Storage Case:

  • Wooden / Aluminium case with velvet or PTFE lining

• Protection:

  • Dust-proof & humidity-controlled

• Positioning:

  • Individual cavities with identification markings

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12. NABL Calibration Certificate Includes

• NABL logo & accreditation number

• Nominal and conventional mass

• Expanded uncertainty (k=2)

• Weight density

• Environmental conditions

• Traceability chain to NPL

• Date of calibration & validity

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13. Applications

• Primary & secondary mass standards

• Calibration of E2 / F1 weights

• High-resolution analytical & micro balances

• Research & national metrology labs

• Pharmaceutical & semiconductor industries

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14. Compliance Summary

✔ OIML R-111 compliant
✔ NABL / ISO-17025 traceable
✔ Ultra-low uncertainty
✔ Metrology-grade performance