ISO 17491-4:2024

Overview

ISO 17491-4:2024 - "Protective clothing - Test methods for clothing providing protection against chemicals - Part 4: Determination of resistance to penetration by a spray of liquid (spray test)" defines a laboratory spray-test method to assess the resistance of full-body chemical protective clothing to inward leakage from liquid sprays. The standard covers two intensity levels: Method A (low-level spray) for limited exposure and Method B (high-level spray) for garments with spray‑tight connections (Type 4 and Type 6 protective clothing). This test addresses spray penetration only and does not cover chemical permeation of materials.

Key Topics and Requirements

• Test principle: an aqueous spray containing a visible dye tracer is applied to a garment worn by a human test subject; internal leakage is detected on an absorbent overall worn underneath.
• Test liquid composition: methyl blue dye (0.20 ± 0.02 g/L) and citric acid stabilizer (2.45 ± 0.05 g/L). A surfactant is added to reach the required surface tension.
• Surface tension targets:
  • Method A: approx. 52.0 ± 7.5 × 10^-3 N/m
  • Method B: approx. 30.0 ± 5.0 × 10^-3 N/m (Example surfactant: Genapol LRO at specified concentrations - ISO gives this as a non‑endorsement example.)
• Apparatus: absorbent overall, calibrated stain procedure (25 ± 5 µL droplet, minimum stain area ≥ 1 cm² after 5 min), turntable (≥60 cm diameter, rotation 1.0 ± 0.1 rpm), spray booth dimensions, spray boom with four nozzles (≈45 cm spacing), hydraulic pump (minimum 400 kPa), stopwatch and other calibrated equipment.
• Procedure notes: requirements for nozzle alignment, liquid temperature (20–30 °C), daily verification of surface tension and temperature, calibrated stain measurement, and defined pass/fail criteria per the relevant product standard.
• Repeatability: Interlaboratory studies reported in Annex D show the method provides repeatable pass/fail outcomes.

Applications and Users

ISO 17491-4:2024 is intended for:

• PPE manufacturers validating garment designs against spray exposure levels (Type 4/Type 6).
• Test laboratories and certification bodies performing standardized spray penetration testing.
• Occupational safety professionals and procurement teams specifying and selecting chemical protective clothing for processes with spray or splash hazards.
• Regulatory and compliance groups referencing standard test evidence in safety assessments.

Practical benefits include objective pass/fail results, harmonized test conditions for procurement comparisons, and guidance on apparatus and test-liquid preparation.

Related Standards

• ISO 11610 (Protective clothing - Vocabulary)
• Other parts of the ISO 17491 series (for related test methods and product-specific requirements)

Keywords: ISO 17491-4:2024, spray test, chemical protective clothing, Type 4, Type 6, resistance to penetration, methyl blue, surface tension, absorbent overall, calibrated stain.