IEC 61508 Safety Case Example: Diving Equipment

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Deep Life's product safety design process is certified to IEC EN 61508, the Gold Standard in Functional Safety and High Integrity. All products designed and managed in accord with that process can be certified to EN 61508, up to SIL 3. We accept projects on a case by case basis to SIL 4, the most onerous level..

Deep Life can support any or all parts of your safety product lifecycle, from concept, definition, hazard and risk analysis, safety assessment and allocation, through the design and implementation of electronics, ASICs, software and mechanics, validation, and onward to production support and maintenance, to the final decomissioning or disposal. Our business exists to improve the stability and success of your business, by improving safety, reducing product liability and operational risks.

As an example of Deep Life's work, we present here a full safety case for a family of diving rebreathers designed by Deep Life. Diving is one of the product areas we specialise in: the others being gas monitoring, and fast ASICs. The rebreathers we design are manufactured and sold through our clients, which include Apollo Military and Open Safety Equipment Ltd. Deep Life managed the entire product lifecycle from conception, through design, production monitoring and recyling. This equipment is the first dive equipment ever to be certified to a recognised Functional Safety standard, achieving IEC EN 61508:2004 at SIL 3 - a very onerous level.

It is hoped that this dissemination promotes greater awareness of the reality of Functional Safety within the marine, subsea oil and diving industries. Deep Life has pioneered the application of Functional Safety in this field. Some sectors in the diving industry oppose Functional Safety vigorously, even vehemently; others have welcomed it as the means to achieve a clean and traceable safety record moving forwards. Many lives can be saved by adopting IEC EN 61508 throughout marine and subsea industry.

Extending Functional Safety systems through the marine and subsea industries is good custodianship. Functional Safety can safeguard resources, avoid profit erosion from accidents, and enhance the health and safety of the workforce. Functional Safety gives strong evidence that management have minimised risks as far as it is economically and technically viable to do so: efficient lifecycle management processes save money in the medium and long term - an intrinsic part of the vocabulary of every business with a long term perspective.

The main safety data is contained in the following document sets:

Safety Integrity Level Assignment for Dive Systems (325KB)
The EN61508 Safety Integrity Level assessment and assignment for the different subsystems and applications for rebreathers. The SIL assignment for eSCR and eCCR is SIL 3 to 4, the communications has a SIL assignment of SIL 2, independent PPO2 monitor is assigned SIL 2, Topside monitoring software is assigned SIL 1.


Formal (maths) models
Maths models for the rebreather, its environment, and decompression algorithms. These are in Matlab and Simulink for ease of use, and for Monte Carlo testing of independently written code.


Accident Database and Reviews
The Comprehensive Database of Rebreather Fatal Accidents, and incident analysis: a data-mine that can improve safety in the design and training processes.


Design Validation Reports
These are the detailed test and validation reports that identify the limits of each subassembly.


A selection from the Formal HAZOP and safety review reports developed for the O.R.Project . The HAZID reviews also contribute to Volume 6 of the FMECA.


There are 10 volumes in total covering the whole design, from top down and from bottom up, for the electronics, software and mechanics, including a Fault Tree Analysis.


Open Revolution Rebreathers
Presentations on Deep Life's Open Revolution family of rebreathers. Further information can be obtained from the OEMs who check, produce and sell these systems.


Exploded Drawings
Full set of exploded drawings for the Open Revolution family of rebreathers.