Overview
EN ISO 12058-1:2018 - "Plastics - Determination of viscosity using a falling‑ball viscometer - Part 1: Inclined‑tube method" specifies the general principles and apparatus for measuring the dynamic viscosity of polymers and resins in liquid, emulsified or dispersed states using an inclined‑tube (Höppler-type) falling‑ball viscometer. The method is intended for Newtonian liquids (viscosity independent of shear rate) over a wide range of viscosities and temperatures.
Key topics and technical requirements
- Measurand and units: dynamic viscosity expressed in mPa·s.
- Measurement range: 0.6 mPa·s to 250 000 mPa·s.
- Temperature range: −20 °C to +120 °C (procedure emphasizes tight temperature control).
- Newtonian behavior: applicable only when shear stress is proportional to shear rate; non‑Newtonian fluids can give different results depending on ball or viscometer geometry.
- Apparatus:
- Inclined measurement tube (falling‑ball tube) with a jacket for thermal control; axis inclined at 10° ± 1° to vertical.
- Tube material: precision borosilicate glass (thermally aged and calibrated).
- Six balls available (diameters approx. 15.81 mm down to 11.0 mm) to cover the viscosity range; calibration constant K depends on tube internal diameter (example tube 15.94 mm ± 0.01 mm).
- Ends closed with plugs (one with capillary) to avoid pressure changes and evaporation.
- Timing and temperature measurement:
- Stopwatch scale interval ≤ 0.1 s (or electronic/automatic timers with comparable accuracy).
- Thermometer graduated ≤ 0.1 °C, calibrated and capable of ±0.03 K resolution; thermometer is immersed in jacket and protected from radiant heat.
- Thermostat must maintain jacket temperature to within ±0.03 K (specified range for stable control).
- Procedure elements: sampling, falling‑time measurement between marked positions, calibration of apparatus and balls, expression of results, precision and reporting requirements.
- Calibration / certification: each viscometer must have a test certificate listing apparatus constants; recalibration required after replacing tube or ball or after aggressive testing.
Applications and users
- Practical for quality control, research and development, and material specification of liquid polymers, resins, dispersions and emulsions that behave as Newtonian fluids.
- Typical users: polymer chemists, materials laboratories, QC engineers, rheology technicians, and manufacturers of plastics, coatings, adhesives and inks.
- Useful when cross‑comparing viscosity data obtained with falling‑ball viscometers (Höppler) or when selecting an appropriate viscometry method for a specified viscosity and temperature range.
Related standards
- ISO 12058 series (other parts on falling‑ball viscometry)
- Normative reference cited: ISO 2811-1 (Paints and varnishes - determination of density - pycnometer method)
Keywords: EN ISO 12058-1:2018, falling‑ball viscometer, inclined‑tube method, Höppler, viscosity determination, polymers, Newtonian, dynamic viscosity, viscometry, plastics testing.
