Overview
ISO 187:2022 - "Paper, board and pulps - Standard atmosphere for conditioning and testing and procedure for monitoring the atmosphere and conditioning of samples" - defines the standard atmosphere, conditioning procedure, and measurement requirements to establish reproducible moisture-equilibrium for pulp, paper and board. The third edition (2022) updates conditioning definitions, measurement procedures (Annex A) and guidance on temperature/relative-humidity interdependence (Annex B).
Key topics and technical requirements
- Standard atmosphere: primary test atmosphere is (23 ± 1) °C and (50 ± 2) % RH. In tropical zones, (27 ± 1) °C and (65 ± 2) % RH is permitted.
- Equilibrium definition: conditioning is achieved when two consecutive weighings at least 1 hour apart differ by ≤ 0.25 % of the specimen mass.
- Preconditioning: when hysteresis can affect results, precondition samples 24 h at 10–35 % RH and ≤ 40 °C (ensure preconditioning RH < conditioning RH). Laboratory sheets made by ISO 5269 methods shall not be preconditioned.
- Conditioning practice: allow free air access to all specimen surfaces; typical conditioning times: ~4 h for paper (longer for higher grammage; boards or special materials may need 48 h+). Minimize handling and avoid touching or breathing on test areas.
- Measurement and monitoring (Annex A): use a thermo‑hygrometer with 0.1 °C temperature resolution and ±2 % RH RH resolution (or equivalent apparatus). Record data every 2 minutes, compute 10‑minute averages and use the 10‑minute averages as test results.
- Control considerations (Annex B): temperature and RH are interdependent - small temperature changes alter RH (table provides change in RH per 0.5 °C). Maintain even air circulation and appropriate control capacity; avoid internal heat/moisture sources.
- Failure and reporting: excursions that could change moisture content require reconditioning; samples exposed to RH > 75 % must be discarded. Test reports must reference ISO 187:2022 and include atmosphere used, conditioning time, preconditioning status, deviations and test date.
Applications and who uses it
- Quality control and R&D laboratories in pulp, paper and packaging industries needing reproducible test conditions.
- Test labs performing physical, optical or mechanical property tests where moisture content affects outcomes.
- Manufacturers of conditioning and climate-control equipment, and standards developers calibrating test rooms and instrumentation.
- Procurement and compliance teams requiring consistent sampling and reporting practices.
Related standards
- ISO 5269-1 and ISO 5269-3 (laboratory sheet preparation) - referenced for laboratory sheet handling and exclusions.
- Historical reference: replaces ISO 187:1990.
Keywords: ISO 187:2022, standard atmosphere, paper conditioning, relative humidity, temperature control, conditioning procedure, thermo-hygrometer, pulp paper board testing.
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