Overview
EN 1237:1995 (adopting ISO 5311:1992, modified) is a CEN standard that specifies procedures for determining the bulk density (tapped) of solid fertilizers (excluding powder fertilizers). The standard defines how to compact a known volume of fertilizer by tapping and calculate tapped bulk density as mass per unit volume (g/cm3). It is not suitable for materials that contain more than 20% by mass of particles larger than 5 mm in diameter. Two complementary methods are covered: a machine‑tapping method and a hand‑tapping method.
Key topics and technical requirements
- Scope and limits
- Applies to dry solid fertilizers; powders and materials with excessive coarse particles (>5 mm, >20% by mass) are excluded.
- Method 2 (hand tapping) is limited to spherical granules and prills, not sharp‑edged grains.
- Sample preparation
- Test samples must be prepared according to ISO 7742 and ISO 8358 (sample reduction and preparation).
- Test methods
- Method 1 - Machine tapping
- Pour fertilizer through a funnel into a specified measuring cylinder, then tap using a tapping machine (specified camshaft frequency ~250 min‑1).
- Typical procedure: controlled discharge time, use of a plastic collar, tap 2 500 times, remove surplus and weigh.
- Method 2 - Hand tapping
- Manual filling and tapping of the measuring cylinder (gentle taps during discharge, final drops/raises), scraping excess and weighing.
- Specific procedural steps include discharge time control and light hand tapping (2–3 taps/s), with final 2 mm–3 mm lifts/drops.
- Measurement and expression
- Bulk density (tapped) = mass of test portion (g) / volume of measuring cylinder (cm3).
- Repeatability: difference between two successive determinations by the same operator should not exceed 0.01 g/cm3.
- Test report requirements
- Include sample identification, method used, numerical result and units, any unusual observations and any deviations or optional operations.
Applications and users
- Useful for fertilizer manufacturers, QC/analytical laboratories, packaging and logistics planners, storage managers and regulators.
- Practical uses:
- Designing packaging and storage capacity (silos, bags, bulk containers).
- Calculating expected volume for bulk shipments and stock management.
- Quality control to ensure consistent physical properties and handling behaviour.
- Regulatory compliance and specification reporting.
Related standards
Keywords: EN 1237:1995, ISO 5311:1992, bulk density tapped, fertilizer testing, tapped bulk density, fertilizer quality control, packaging design, storage density.