🎓 Lesson 14
D5
Executing ISO 5682-2 Hydraulic Characterization Tests
ISO 5682-2 is a standardized test method that measures how well a sprayer nozzle delivers liquid—like water or slurry—by checking its flow rate, spray angle, and droplet size under controlled pressure.
🎯 Learning Objectives
- ✓ Calculate volumetric flow rate from pressure and nozzle orifice data
- ✓ Analyze spray angle deviation using ISO 5682-2’s optical measurement protocol
- ✓ Apply coefficient of uniformity (CU) to evaluate spray distribution quality
- ✓ Explain how droplet size (Dv50) influences drift potential and deposition efficiency
- ✓ Design a compliant test setup adhering to ISO 5682-2 environmental and instrumentation requirements
📖 Why This Matters
In mining, hydraulic nozzles are critical for dust suppression, ore washing, and reagent application in hydrometallurgy. A poorly characterized nozzle can waste 30–50% of water or chemical dosage—or worse, fail to suppress respirable dust (e.g., silica), risking health compliance and operational safety. ISO 5682-2 provides the universal 'language' engineers use to specify, compare, and validate nozzles—ensuring performance is repeatable, auditable, and fit for purpose.
📘 Core Principles
Hydraulic characterization rests on three interdependent domains: (1) Flow dynamics—governed by Bernoulli and orifice equations, where pressure drop drives volumetric delivery; (2) Spray geometry—defined by the solid cone, flat fan, or hollow cone pattern shape, quantified by spray angle and axial symmetry; and (3) Atomization physics—where fluid properties (viscosity, surface tension), nozzle design (orifice geometry, swirl chamber), and pressure jointly determine droplet size distribution. ISO 5682-2 standardizes measurement conditions (e.g., stable ±0.5 bar pressure, 20 ± 2 °C water, calibrated collection trays or laser diffraction systems) to isolate nozzle behavior from external variables—enabling fair comparison across brands and models.
📐 Coefficient of Uniformity (CU)
CU quantifies spray distribution evenness across a target plane—critical for ensuring consistent dust suppression or reagent coverage. It is calculated from mass collected in equally spaced radial trays aligned perpendicular to the spray axis. A CU ≥ 85% indicates acceptable uniformity per ISO 5682-2 Annex C.
Coefficient of Uniformity (CU)
CU = 100 × [1 − Σ|X_i − X̄| / (n × X̄)]Quantifies spatial consistency of spray distribution across collection trays.
Variables:
| Symbol | Name | Unit | Description |
|---|---|---|---|
| X_i | Mass collected in tray i | g | Measured liquid mass in each sequential tray |
| X̄ | Mean mass | g | Average of all tray masses |
| n | Number of trays | dimensionless | Minimum n = 8 per ISO 5682-2 Annex C |
Typical Ranges:
Acceptable industrial nozzles: 85 – 98%
💡 Worked Example
Problem: During an ISO 5682-2 test, eight 100 mm-wide aluminum trays were placed 500 mm from a flat-fan nozzle at 300 kPa. Collected masses (g) were: 12.4, 13.1, 11.9, 12.7, 13.3, 12.0, 12.6, 12.2.
1.
Step 1: Compute mean mass = (12.4 + 13.1 + 11.9 + 12.7 + 13.3 + 12.0 + 12.6 + 12.2) / 8 = 12.525 g
2.
Step 2: Calculate absolute deviations from mean: |12.4−12.525| = 0.125, etc.; sum of absolute deviations = 1.25 g
3.
Step 3: CU = 100 × (1 − [sum of absolute deviations / (n × mean)]) = 100 × (1 − [1.25 / (8 × 12.525)]) = 100 × (1 − 0.01246) = 98.75%
Answer:
The result is 98.75%, which falls within the acceptable range of ≥85% per ISO 5682-2.
🏗️ Real-World Application
At the Escondida copper mine (Chile), dust suppression nozzles on haul truck washdown stations failed to meet regulatory PM10 control targets. Post-ISO 5682-2 testing revealed CU values of only 62% (due to worn orifice inserts and inconsistent supply pressure) and Dv50 > 450 µm—too coarse for effective airborne particle capture. After replacing nozzles with ISO-certified flat-fan units (CU ≥ 92%, Dv50 = 210–280 µm at 250 kPa), dust-related downtime dropped 40% and regulatory non-conformance incidents ceased for 18 months.
🔧 Interactive Calculator
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