ISO 6425:2018

Overview

ISO 6425:2018 - "Horology - Divers' watches" is the international standard that defines requirements and test methods for divers’ watches (including saturation divers’ watches). It applies to watches designed to withstand diving to at least 100 m and that include a secured diving time indicator visible in darkness. The standard specifies performance criteria, laboratory tests for homologation (type testing) and production checks, plus the marking manufacturers may apply.

Key topics and technical requirements

• Scope and purpose: Requirements for SCUBA and saturation diving watches; Annex A covers saturation-diving specifics.
• Diving time indicator: Must be secured against accidental operation and readable to a resolution of 1 minute or better for at least 60 minutes; analogue 5‑minute marks must be clear.
• Visibility tests:
  • In light: legible at a minimum of 50 lx.
  • In dark: evaluated after prescribed light exposure (ISO 17514) with checks at 25 cm, 180 min post-exposure; time and diving-time readability must meet an uncertainty of ±2.5 min or better.
• Type testing sequence (homologation): Visibility → Magnetic resistance → Temperature cycling → Salt spray (with bracelet) → Shock resistance (watch head) → Water-resistance → Shock resistance (free-fall) → Resistance of attachments.
• Magnetic and shock resistance: Tested in accordance with referenced standards (ISO 764 for magnetic, ISO 1413 for shock).
• Environmental durability:
  • Temperature cycling (including submersion at low temperature).
  • Salt spray corrosion test with bracelet (ISO 9227).
  • Condensation and water‑resistance tests (functional checks in shallow water and overpressure tests).
• Manufacturing checks: Every production watch must pass the water overpressure test (100% single-watch testing).
• Marking and documentation: Clause 5 defines permitted markings; Annex D provides usage and maintenance recommendations.

Practical applications - who uses ISO 6425

• Watch manufacturers and designers (product development, quality, compliance).
• Test laboratories and certification bodies (type approval, batch testing).
• Retailers and buyers (to verify claims such as “ISO 6425 certified” or “diver’s watch 200 m”).
• Professional divers, dive operators and technical procurement teams relying on verified water resistance and durability.

Related standards

• ISO 764:2002 - Magnetic resistant watches
• ISO 1413:2016 - Shock-resistant wrist watches
• ISO 9227:2017 - Salt spray test
• ISO 17514:2004 - Photoluminescent deposits test methods
• ISO 22810:2010 - Water-resistant watches

ISO 6425 is the primary global reference for designing, testing and certifying reliable divers’ watches, ensuring safety and durable performance under real diving conditions.