Machine Design

# Designing Safer Products Proactive Hazard Analysis

Hazard analysis is the foundation of many other product-safety activities.

The objective of productsafety efforts is to correct or address safety problems.

There are many types of hazard analysis: Failure Mode and Effects Analysis (FMEA), Fault Tree Analysis (FTA), and Preliminary Hazard Analysis (PHA), among others. Some are also more complicated and take more effort to implement. FMEA and FTA, for example, involve mathematical modeling with very detailed historical data. Problem is, the data often are not available.

My approach is to use PHA. It does not give any statistical information but does a good job of using history and looking at all identifiable hazards from different viewpoints.

PHA is a methodical way to examine a product and anticipate any potential hazards that might result from it. There are several questions that get asked in any PHA investigation. Typical queries:

• Does the product have a sound design, or are there inherent safety problems?
• Who will use the product, and how will they use it?
• Where will the product be used?
• What sort of misuse can be anticipated, and will any misuses cause hazardous situations?
• How will the product be shipped and stored?
• How will the product be disposed?
• Does the product contain anything that will contaminate a landfill, such as a mercury switch?

Hazard analysis is most effective when conducted early in a product design phase. The reason is that a problem not identified until after the product is sold can bring additional expenses such as a product recall, a field retrofit program, and, last but worst, an expensive product liability court defense.

Developers complete a hazard analysis using a sequence of procedures something like this:

• Identify all safety hazards.
• Evaluate the risk and severity of each hazard.
• Determine the approach to address each hazard: Do we redesign the product, guard the hazard, or address the hazard with warning labels?

A real-life example illustrates the power of PHA. A manufacturer needed to determine whether a product was too dangerous for commercial introduction. He made the decision by performing a PHA on a cardboard model just before entering the design phase of the product. The result: The product was indeed too dangerous. There were major changes made in the concept as a result of this simple check before a design team wasted precious days on more detailed work.

Hazard analysis takes into consideration not just users of the product, but also others who come in contact with it. A thorough review would consider service personnel, shippers, manufacturers of the product, installers, and even those who might walk past users in an exposed area.

Full documentation must start when a hazard analysis begins and should continue through all corrective measures that result from the analysis. If worse comes to worse, any holes in the documentation may be construed as a cover-up. Good documentation is extremely useful in defending a product liability lawsuit.

The leaders in this regard are the auto manufacturers.

Lanny Berke

Lanny Berke is a registered professional engineer and a Certified Safety Professional involved in forensic engineering since 1972. Got a question about safety? You can reach Lanny at [email protected].