ISO 14119:2024 norm for safety interlocks
What is new in the ISO 14119:2024?
And why is this norm important?
Anyone working with moving machinery knows that access to hazardous areas must be strictly controlled and that safety interlocks play a central role in this process. ISO 14119 is the international standard that defines the requirements for safety interlocking devices. In 2024, this standard was significantly revised to improve operator protection and to better align with modern technologies and risk assessment strategies. For engineers, procurement specialists and HSE managers, this revision means existing design choices must be re-evaluated. It’s no longer just about what technically works, but also about what demonstrably meets the latest requirements for tamper resistance, functional safety and mechanical reliability. Fortress Safety offers interlock solutions that are directly aligned with these new requirements. But what has actually changed?
The revised edition of ISO 14119 brings improved clarity in terms and structure, but the most important changes can be grouped into four key areas: prevention of defeat, mechanical testing, trapped key interlocking, and diagnostics in series-connected devices.
A major improvement is Table 5, which provides guidance on additional design measures in cases where operators may be motivated to bypass safety interlocks. This includes both intentional and unintentional defeat, such as overriding a device to increase speed or ease of access. The standard now provides recommendations per type of interlock, and in cases of higher manipulation risk – such as with basic mechanical actuators – the use of coded solutions is strongly recommended. RFID-coded actuators, as used in Fortress Safety’s amGardpro series, significantly reduce the likelihood of tampering due to their uniquely coded mechanisms. This aligns with the core message of the revised standard: safety components must not only be present, but also effective in real-world use.
The revisited edition also introduces new mechanical testing procedures in Annex I, covering locking force and impact resistance. An interlock must now demonstrate that it remains functional and secure even under mechanical stress, such as when subjected to forceful pulling or impact. This is especially important in environments with heavy machinery or frequent physical interactions. Fortress’s use of metal housings and robust mechanical design ensures compliance with these new requirements – and offers documented test results as proof.
Another key change is the integration of ISO/TS 19837 as Annex K, which sets requirements for trapped key interlocking systems. These systems enforce a defined sequence of operations before access is granted, often used in applications involving energy isolation or zone control. Fortress provides modular trapped key systems, including exchange units, in which keys are only released when specific conditions are met. For example, a door can only be unlocked once energy has been safely removed and the corresponding key is inserted into a separate unit. This ensures physical safety without the need for software-based logic, a crucial advantage in ATEX zones or in low-voltage environments.
Lastly, the former technical report ISO/TR 24119 is now included as Annex J. This section addresses fault masking, a risk that occurs in series-wired interlocks where one fault can be hidden by another. In daisy-chain setups, such as with multiple doors connected in sequence, faults may go undetected. Annex J provides guidance on assessing the diagnostic coverage (DC) and the achievable Performance Level (PL) of the complete system. Fortress’s tGard system can be configured with diagnostic feedback to allow detection at the individual device level – significantly reducing the risk of undetected failures.
Why do these changes to ISO 14119 matter?
These updates are not theoretical. They impact the day-to-day reliability and safety of machines in real operation. ISO 14119:2024 supports broader risk reduction strategies under ISO 12100 and connects directly to functional safety standards such as ISO 13849 and IEC 62061. For machine builders working under CE certification, and soon under the new EU Machinery Regulation (EU 2023/1230), these updated requirements are essential for compliance. Procurement teams also need to update their specifications. Whereas a basic door switch may have been sufficient in the past, the new standard demands components that are tamper-resistant, test-verified and able to provide traceable safety performance. This calls for close collaboration with specialised safety suppliers and a stronger focus on technical documentation, testing and verification during the procurement process.
Fortress Safety has long specialised in designing interlocking solutions that meet high standards for durability, tamper resistance, and integration into advanced safety systems. RFID-coded interlocks, high-strength metal housings and modular diagnostic options are all part of a product portfolio that aligns with ISO 14119:2024. The amGardpro range offers heavy-duty interlocks with RFID and fieldbus communication; the tGard system provides compact, modular safety with optional diagnostics; and the FRANK trapped key range ensures enforced safety procedures through physical key sequencing, fully compliant with Annex K. Whether you’re working with a multi-zone production line, a complex packaging installation, or a maintenance scenario involving energy isolation, Fortress provides technically robust and regulation-compliant solutions.
For more information on Fortress Safety products, or to find the right solution for your application, contact our sales engineers at sales@usp-safety.com or call +31 (0)10 822 44 00.
