EN ISO 172:1998

Overview

EN ISO 172:1998 - Plastics: Phenol-formaldehyde mouldings - Detection of free ammonia defines a qualitative laboratory method to detect the presence of free ammonia or other volatile bases in phenol-formaldehyde (phenoplast) mouldings. The method is intended for use where the absence of free ammonia is a requirement for material acceptance, safety or further processing.

The procedure detects alkaline vapours released from a moistened powdered sample by exposing a universal indicator paper to the vapour inside a sealed flask. The method is simple, rapid and suitable as a screening test for free ammonia in thermosetting materials.

Key Topics

• Scope and purpose: Qualitative detection of free ammonia and volatile bases in phenol-formaldehyde mouldings.
• Principle: Alkaline vapours from a powdered, moistened sample change the colour of a universal indicator paper when contained in a sealed vessel.
• Sample preparation: Reduce a representative portion of the moulding to powder by filing, milling, grinding, turning or drilling, taking care to avoid undue heating of the material.
• Typical parameters (from the standard):
  • Test portion: approximately 1 g
  • Container: glass-stoppered flask, 50 ml capacity
  • Indicator: universal indicator test paper (pH range 1.0 to 11.0)
  • Balance accuracy: 0.01 g
  • Exposure time: examine the indicator paper after 30 minutes
• Result interpretation: If the indicator paper changes colour consistent with alkaline vapour exposure, report the presence of free ammonia or other volatile bases; if no colour change occurs, report absence.
• Reporting requirements: The test report shall include the standard reference, sample identification, method of powdering, and the presence or absence of free ammonia/volatile bases.

Applications

This ISO method is valuable for stakeholders involved in plastics production, quality assurance and material safety:

• Incoming inspection of phenol-formaldehyde mouldings to confirm absence of free ammonia before assembly, coating or bonding.
• Routine screening in production or QA labs to detect contamination or incomplete cure that may release volatile bases.
• Safety and compliance checks where ammonia-free specification is required by customer, regulatory or downstream process needs.

Benefits of using the EN ISO 172 qualitative method include its low cost, minimal equipment requirements, and ease of integration into standard QA workflows.

Related Standards

• ISO standards for plastics testing and terminology developed by ISO/TC 61 (Plastics).
• Complementary material testing standards for thermosetting resins and phenolic mouldings (refer to current national or regional standards for additional quantitative analysis methods).

For implementation, follow the standard text for exact procedural steps, sample handling and reporting to ensure consistent, repeatable screening for free ammonia in phenol-formaldehyde mouldings.