ISO 17168-5:2018

Overview

ISO 17168-5:2018 specifies a laboratory test method to evaluate the air‑purification performance of semiconducting photocatalytic materials for the removal of methyl mercaptan (methanethiol) under simulated indoor lighting. Intended primarily for flat-sheet, board, plate and honeycomb ceramic materials (and plastics/papers with ceramic microcrystals), the standard defines how to expose a test piece to a model polluted air stream while irradiating with an indoor‑light source and measuring net pollutant removal. This document is focused on air purification performance only and does not apply to powders/granular photocatalysts or to other attributes such as self‑cleaning, antifogging or antibacterial actions.

Key Topics and Requirements

• Test principle: Continuous flow photoreactor exposure of a test piece under indoor light; comparison of illuminated vs dark tests to separate photocatalytic removal from simple adsorption.
• Test specimens: Flat or honeycomb forms, typical test-piece area and spacing specified (example: 99.0 × 49.0 mm test piece with a 5.0 ± 0.5 mm air gap to the optical window).
• Light source & illumination: Cool‑white fluorescent lamp with a UV sharp cut‑off filter; illuminance at specimen surface 6 000 lx ± 300 lx, uniformity ±5 %.
• UV cut‑off filter specs: Transmittance <0.1 % at <365 nm, <1 % at 380 nm, >80 % between 400–780 nm; half‑transmittance wavelength at 390 nm ± 5 nm.
• Test gas & flow control: Standard methyl mercaptan cylinder (commonly 100–1 000 µl/l in N2); thermal mass‑flow controllers and humidifier to supply pollutant at controlled flow, temperature and humidity. Flow accuracy within ±5 % is recommended.
• Photoreactor design: Low‑adsorption materials (acrylic, stainless steel, glass, fluoropolymers), optical window material (quartz/borosilicate), and flow path that ensures test gas passes only between window and test piece.
• Analysis: Methyl mercaptan quantified by gas chromatography; calculations provide net removal quantity (µmol) and removal percentage.
• Limitations: Not applicable where stable methyl mercaptan concentration cannot be maintained in test time.

Applications and Users

• Manufacturers of photocatalytic construction materials (coatings, panels, honeycombs)
• R&D teams developing indoor‑light‑active photocatalysts (e.g., TiO2‑based semiconducting oxides)
• Accredited testing laboratories and conformity assessment bodies (ISO/IEC 17025)
• Product certification bodies and environmental engineers assessing indoor air purification claims

Related Standards

• ISO 17168-1 (Removal of nitric oxide) - comparable test setup
• ISO 22197 series - other pollutant removal methods
• ISO 14605 - light source requirements for indoor photocatalyst testing
• ISO 6145-7 - calibration of thermal mass‑flow controllers
• ISO/IEC 17025 - testing laboratory competence

Keywords: ISO 17168-5:2018, fine ceramics, photocatalytic materials, air‑purification, methyl mercaptan, indoor lighting, TiO2, photoreactor, gas chromatography.