Designing Effective Machine Safety Signs

Safety signs are an important part of risk reduction for machinery – they are intended to identify and warn against specific hazards. They also may describe safety precautions, advise evasive actions to take or provide other directions to eliminate or reduce hazards.

When designing machine safety signs, it is important to use a consistent visual layout along with a uniform system for the recognition of potential personal-injury hazards. This will help to effectively communicate hazard information.

For safety signs that will be used on machines in the United States, the best standards to reference are ANSI Z535.4-2007, Product Safety Signs and Labels; ANSI Z535.3-2002, Criteria for Safety Symbols; and ANSI Z535.1-2006, Safety Colors. Together, these standards contain the information needed to specify formats, colors and symbols for machine safety signs. They also provide information on widely recognized principles that can aid in the development of effective safety signs.

ANSI Z535 standards can be purchased online at http://global.ihs.com.

Types of Panels

A machine safety sign usually consists of three types of panels: a signal-word panel, a message panel and a safety-symbol panel.

1. Signal-Word Panel

The signal-word panel is the area of a machine safety sign that contains the safety alert symbol (exclamation point inside an equilateral triangle) followed by the signal word. The signal word is the word that calls attention to the safety sign and designates the hazard classification. This classification is based on the probability of being injured if the hazard is not avoided and on the severity of the resulting injury.

For machinery, the three hazard classifications are designated by the signal words “DANGER,” “WARNING” and “CAUTION.” Annex E of ANSI Z535.4-2007 provides excellent guidance for estimating risk and selecting a signal word. ANSI Z535.1-2006 provides technical definitions, color standards and color tolerances for the safety colors specified for the signal-word panel by ANSI Z535.4-2007.

2. Message Panel

The message panel is the area of the safety sign that contains the word messages that typically identify the hazard, indicate how to avoid it and advise of the consequence of not avoiding it. The order in which the message panel’s content appears is flexible; however, factors to consider when determining the order include the target audience’s degree of prior knowledge of the hazard and the reaction time required to avoid the hazard.

When developing word messages, many issues must be considered – from sentence structure to typesetting specifications – so that they are concise and easily understood. A few ways to do this are to:

• Write in “headline style.”
  
• Use active voice.
  
• Avoid prepositional phrases.
  
• Use sentence-style capitalization.
  
• Use sans-serif fonts.
  
• Use left-aligned text.
  

In addition, lettering must be of a size that enables a person to read the message-panel text at a safe viewing distance from the hazard. Determination of safe viewing distance for the message-panel text must take into consideration a reasonable hazard-avoidance reaction time.

3. Safety-Symbol Panel

The safety-symbol panel is the area of the safety sign that contains the safety symbol. The safety symbol is a graphic representation intended to convey a message without the use of words. It may represent a hazard, a hazardous situation, a precaution to avoid a hazard, a result of not avoiding a hazard or any combination of these messages.

The safety symbol should be readily understood and should effectively communicate the message. To aid in the design, evaluation and use of safety symbols, ANSI Z535.3-2002 should be used. This standard’s purpose is to promote the adoption and use of uniform and effective safety symbols for safety communications.

Annex A of this standard contains several principles and guidelines for the graphical design of safety symbols, and it shows numerous examples of the human body and specific body parts in various positions and orientations including their interaction with various hazards.

The Importance of Safety Signs

When designed and used properly, safety signs can play an important role in risk reduction for machinery. The ANSI Z535 standards are the best references, as they specify formats, colors and symbols for machine safety signs. They also provide information on widely recognized design principles.

Use of these standards to develop a uniform visual layout and a consistent system for the recognition of potential hazards will help in designing the most effective machine safety signs.

Ryan Ebens is president of Danray Products LLC, a Rockton, Ill.-based manufacturer of machine safeguards and accessories, including machine safety shields, lathe chuck shields, portable (handheld) chip/coolant shields, machine lamps, safety signs and a guard safety scale for compliance with applicable OSHA, ANSI and Canadian Standards Association safety standards for machinery.