Overview
ISO 14436:2010 specifies a standard tap water for pulp drainability measurements with an electrical conductivity between 40 mS/m and 150 mS/m. The document defines the composition, preparation and verification of this water (based on addition of a magnesium salt) to reduce variability in drainability tests caused by differing electrolyte levels in pulps. ISO 14436:2010 is applicable to all kinds of pulps and is intended for use in disintegration, beating and drainability determinations.
Key Topics and Requirements
- Conductivity range: 40 mS/m to 150 mS/m is required for the standard tap water.
- Primary reagent: magnesium sulfate (MgSO4 or MgSO4·7H2O) is used to raise conductivity; a recommended concentration is c(MgSO4) ≈ 0.5 g/L.
- Stock solution example: 100 g/L MgSO4 (or 204 g/L MgSO4·7H2O) and an example dosing of 5 mL stock per litre of water.
- Base water quality: distilled, deionized or potable tap water with conductivity ≤ 20 mS/m and trivalent ion (Fe, Mn, Al) concentrations ≤ 1 mg/L.
- Verification: final conductivity must be checked using the procedure in ISO 6587.
- Reporting: when reporting SR (Schopper‑Riegler), CSF (Canadian Standard Freeness) or WRV results, laboratories must state that standard tap water in accordance with ISO 14436 was used.
- Rationale: Annex A shows that raising conductivity to ~30–40 mS/m neutralizes the effect of small pulp-borne electrolyte variations on drainability (SR or CSF).
Practical Applications
- Ensures consistent, reproducible drainability measurements across labs and production sites by stabilizing electrolyte background in pulp suspensions.
- Used in quality control, laboratory testing, R&D and process development in the pulp and paper industry.
- Helpful for instrument manufacturers and test-lab service providers who supply or validate pulp testing equipment and procedures.
- Applicable where SR or CSF values are used to specify or compare pulp physical properties; reduces misleading variability caused by fluctuating salts in incoming pulp samples.
Related Standards
- ISO 6587 - procedure for determination of conductivity of aqueous extracts (used to verify conductivity).
- ISO 14487 - specification and preparation of standard distilled/deionized water for physical testing (related reference for laboratory water).
Keywords: ISO 14436:2010, standard tap water, drainability measurements, conductivity 40 mS/m to 150 mS/m, pulp testing, Schopper‑Riegler, magnesium sulfate, CSF, ISO 6587.