Design for Safety

Understanding Design for Safety in Modern Product Development

In the realm of product development, few considerations carry as much weight as safety. Design for Safety (DfS) represents a systematic approach to identifying, evaluating, and mitigating potential hazards throughout the entire product lifecycle. For engineering firms operating in Atlantic Canada, where industries range from marine equipment manufacturing to agricultural machinery and energy sector components, integrating safety principles from the earliest design stages is not merely best practice—it is an essential requirement for protecting end users, meeting regulatory obligations, and ensuring long-term commercial success.

The fundamental premise of Design for Safety is straightforward: it is far more effective and economical to engineer hazards out of a product during the design phase than to address them through warnings, training, or protective equipment after the fact. Studies consistently demonstrate that approximately 70-80% of a product's lifecycle costs are determined during the design phase, and this principle extends directly to safety-related expenses including warranty claims, liability costs, and regulatory compliance efforts.

For manufacturers and product developers across Nova Scotia and the Maritime provinces, understanding and implementing robust DfS methodologies can mean the difference between a successful product launch and costly recalls or liability issues. This comprehensive guide explores the key principles, methodologies, and practical applications of Design for Safety in contemporary product development.

The Hierarchy of Controls: A Foundation for Safe Design

At the core of every effective Design for Safety programme lies the hierarchy of controls—a systematic framework for prioritising safety measures based on their effectiveness. This internationally recognised approach, codified in standards such as CSA Z432 and ISO 12100, provides engineers with a structured methodology for addressing identified hazards.

Elimination and Substitution

The most effective safety measures involve completely eliminating hazards or substituting hazardous elements with safer alternatives. In practical terms, this might involve:

• Redesigning a mechanism to remove pinch points entirely rather than guarding them

• Substituting toxic materials with environmentally friendly alternatives that pose no health risks

• Eliminating sharp edges through design geometry changes rather than adding edge protection

• Removing the need for manual intervention in hazardous processes through automation

For example, a Nova Scotia-based manufacturer developing fish processing equipment might eliminate knife-change hazards by designing a tool-free blade replacement system that keeps operators' hands away from cutting edges at all times, rather than relying on cut-resistant gloves and training.

Engineering Controls

When elimination is not feasible, engineering controls provide the next level of protection. These physical safeguards include:

• Fixed guards that prevent access to hazardous areas

• Interlocked barriers that shut down equipment when opened

• Light curtains and safety scanners that detect personnel presence

• Two-hand controls requiring simultaneous activation

• Emergency stop systems with redundant circuits

Engineering controls must be designed to be tamper-resistant, as studies indicate that up to 25% of machine-related injuries involve defeated or bypassed safety devices. Effective DfS anticipates these behaviours and designs systems that maintain protection even when users attempt workarounds.

Administrative Controls and Warnings

The lowest levels of the hierarchy—administrative controls, training, and warning labels—should only be relied upon when higher-order controls are genuinely impractical. While these measures have their place, they depend entirely on human compliance and attention, making them inherently less reliable than engineered solutions.

Risk Assessment Methodologies for Product Design

Effective Design for Safety requires rigorous risk assessment processes that systematically identify potential hazards and evaluate their associated risks. Several methodologies have proven particularly valuable in product development contexts.

Failure Mode and Effects Analysis (FMEA)

Design FMEA (DFMEA) examines potential failure modes of product components and systems, evaluating their effects on safety, reliability, and performance. The methodology assigns numerical ratings for:

• Severity (S): The seriousness of the failure's consequences, rated 1-10

• Occurrence (O): The likelihood of the failure occurring, rated 1-10

• Detection (D): The probability of detecting the failure before it reaches the customer, rated 1-10

The Risk Priority Number (RPN), calculated as S × O × D, helps prioritise design improvements. Items with RPNs exceeding threshold values (typically 100-125) require corrective action before design release. Modern approaches increasingly emphasise the Action Priority method outlined in AIAG-VDA FMEA guidelines, which provides more nuanced prioritisation than traditional RPN calculations.

Hazard and Operability Study (HAZOP)

Originally developed for chemical process industries, HAZOP methodology has been successfully adapted for product design applications. The technique uses guide words (No, More, Less, Reverse, Other Than) combined with process parameters to systematically explore deviations from intended design function.

For Maritime manufacturers developing pressure vessels, fluid handling systems, or thermal processing equipment, HAZOP provides a structured approach to identifying potentially dangerous operating conditions that might not be apparent through conventional design review.

Fault Tree Analysis (FTA)

Fault Tree Analysis works backward from an undesired top event to identify the combinations of component failures and conditions that could cause it. This deductive approach is particularly valuable for safety-critical systems where understanding failure pathways is essential.

For products with target reliability requirements—such as those used in Nova Scotia's offshore energy sector—FTA can demonstrate that design meets quantitative safety targets. A typical safety-critical system might require failure probability below 10^-6 per operating hour, validated through rigorous fault tree calculations.

Canadian Regulatory Framework and Standards Compliance

Product developers in Canada must navigate a complex regulatory landscape that includes federal legislation, provincial requirements, and voluntary standards that often become mandatory through regulatory reference or contractual obligations.

Canada Consumer Product Safety Act (CCPSA)

The CCPSA establishes the general requirement that consumer products must not pose unreasonable dangers to human health or safety. Products that present serious safety defects may be subject to recalls, and manufacturers can face significant penalties for non-compliance. The Act places primary responsibility on manufacturers and importers to ensure their products are safe before reaching the market.

CSA and Other Standards

Canadian Standards Association (CSA) standards provide detailed technical requirements for numerous product categories. Key standards relevant to Design for Safety include:

• CSA Z432: Safeguarding of Machinery—the fundamental Canadian standard for machine safety

• CSA C22.2 series: Electrical safety requirements for equipment and products

• CSA Z460: Control of hazardous energy—lockout and other methods

• CSA Z1002: Occupational health and safety—hazard identification and elimination

For products destined for export or used in regulated industries, international standards such as ISO 12100 (Safety of machinery—General principles for design), IEC 62368-1 (Audio/video and IT equipment safety), and sector-specific requirements from organisations like Transport Canada or Health Canada may apply.

Provincial Considerations

Nova Scotia's Occupational Health and Safety Act and associated regulations establish requirements that affect product design when equipment will be used in workplace settings. Products must be designed to facilitate safe installation, operation, maintenance, and eventual disposal in compliance with these requirements. Understanding how your product will be used across Atlantic Canada's diverse industrial landscape—from Cape Breton's manufacturing facilities to New Brunswick's forestry operations—ensures designs meet regional workplace safety expectations.

Human Factors and Ergonomic Design Considerations

Design for Safety must account for the humans who will interact with products throughout their lifecycle. Human factors engineering—the scientific discipline concerned with understanding interactions between humans and system elements—provides essential insights for safe design.

User Population Analysis

Effective DfS requires understanding the full range of potential users, including their:

• Physical characteristics: Anthropometric data covering height, reach, strength, and mobility variations across the 5th to 95th percentile of the user population

• Cognitive capabilities: Attention span, decision-making processes, and susceptibility to error under various conditions

• Training levels: Range from novice operators to experienced technicians

• Environmental factors: Operating conditions including lighting, noise, temperature extremes common in Maritime industrial settings, and personal protective equipment requirements

Products designed for Atlantic Canada's harsh winter conditions, for example, must account for operators wearing heavy gloves, reduced visibility during snowstorms, and cold-induced decrements in manual dexterity and cognitive function.

Error-Tolerant Design

Human error is inevitable, and safe designs must accommodate this reality. Error-tolerant design principles include:

• Affordances: Design elements that suggest correct usage (handles that indicate proper grip, buttons sized for appropriate force)

• Constraints: Physical features preventing incorrect assembly or operation (asymmetric connectors, interlocks)

• Feedback: Clear indication of system state and response to user inputs

• Reversibility: Ability to undo actions before consequences occur

Research indicates that well-designed interfaces can reduce human error rates by 50-90% compared to poorly designed alternatives. Investing in human factors analysis during product development yields significant safety dividends throughout the product lifecycle.

Lifecycle Safety Considerations

Design for Safety extends beyond operational use to encompass every phase of a product's existence, from manufacturing through disposal.

Manufacturing Safety

Product designs should facilitate safe manufacturing processes. This includes specifying materials that can be processed without exposing workers to hazardous substances, designing geometries that minimise sharp edges and handling hazards during assembly, and avoiding tolerances so tight that they create quality pressure leading to safety shortcuts.

Installation and Commissioning

Products must be designed for safe installation, considering:

• Weight distribution and lifting points for heavy components

• Electrical and mechanical connection safety during setup

• Clear marking of hazards that exist before protective systems are activated

• Commissioning procedures that verify safety system functionality

Maintenance and Service

Maintenance activities account for a disproportionate share of product-related injuries because they often require defeating normal safeguards. DfS addresses this through:

• Designing for zero-energy maintenance where possible

• Providing clear lockout/tagout points compliant with CSA Z460

• Locating maintenance points away from persistent hazards

• Specifying service intervals that prevent degradation to unsafe conditions

End-of-Life Considerations

Safe designs anticipate eventual decommissioning and disposal. This includes avoiding materials that become hazardous during demolition, designing for safe disassembly, and marking components containing hazardous substances for proper handling.

Documentation and Design History

Comprehensive documentation serves multiple critical functions in Design for Safety: it ensures design decisions are properly communicated, provides evidence of due diligence for liability protection, and creates institutional knowledge that improves future designs.

Essential Documentation Elements

A complete DfS documentation package typically includes:

• Risk assessment records: FMEA worksheets, HAZOP studies, fault trees, and action closure evidence

• Standards compliance matrix: Mapping of applicable requirements to design features

• Test reports: Verification that safety features function as intended

• Design rationale: Explanation of why specific safety approaches were selected

• User documentation: Operating instructions, warnings, and maintenance procedures

Maintaining this documentation throughout the design process—not reconstructing it after the fact—ensures accuracy and demonstrates the systematic approach courts and regulators expect in liability matters.

Partner with Experts for Safe, Successful Product Development

Design for Safety is not merely a regulatory checkbox—it represents a fundamental commitment to protecting the people who manufacture, install, operate, and maintain the products we create. For companies across Nova Scotia and Atlantic Canada, integrating robust DfS methodologies into product development processes delivers measurable benefits: reduced liability exposure, improved regulatory compliance, enhanced market acceptance, and most importantly, products that serve their users without causing harm.

Successfully implementing Design for Safety requires expertise spanning risk assessment methodologies, applicable standards, human factors engineering, and practical design solutions. Sangster Engineering Ltd. brings decades of professional engineering experience to product development challenges across Atlantic Canada. Our team understands both the technical requirements of safe design and the practical realities facing Maritime manufacturers.

Whether you are developing new products, updating existing designs to meet current safety standards, or seeking independent review of your safety documentation, Sangster Engineering Ltd. provides the expert guidance you need. Contact our Amherst office today to discuss how we can help ensure your next product development project achieves the highest standards of safety and regulatory compliance while meeting your commercial objectives.

Partner with Sangster Engineering

At Sangster Engineering Ltd. in Amherst, Nova Scotia, we bring decades of engineering experience to every project. Serving clients across Atlantic Canada and beyond.

Contact us today to discuss your engineering needs.