Occupational Safety & Health

16 Sep, 2011

What is a “Spark-proof” tool?

Posted by: admin In: Chemical Safety|Chemical Spill|Confined space|Fire Safety|Gas Detector|OSH concept

“Spark-proof”, “non-sparking”, “spark reduced” or “spark-resistant” tools are tools made of metals such as brass, bronze, copper-aluminum alloys (aluminum bronze), Monel metal (copper-nickel alloy), or copper-beryllium alloys (beryllium bronze).

Usually, hand tools are often manufactured of steel alloys for its strenght at work. “Spark-proof” metals have lower tensile strength than steels. It means the metal has less strength or resistance to tearing apart when stretched under test conditions. It also means that these tools are softer, higher wear and tear compare to ordinary steel tools, and have to be redressed more often.

What is the most important thing to know about “non-sparking” tools?

Non-sparking tools also generate sparks sometimes referred to as “cold sparks”. These cold sparks have a low heat level and do not ignite carbon disulfide, which has the lowest ignition point of any substance known to man. Therefore while “non-sparking” tools would have lower risk of a spark, but they do not eliminate the possibility of sparks. The name “non-sparking” is somehow misleading because these tools are capable of producing a spark. The term of  “reduced-sparking tools” better describes these tools.

Non-metals like wood, leather, and plastic are suitable for some tools like shovels, scrapers or scoops and do not pose a friction spark hazard.

Non-sparking tools provide protection against fires and explosions in environments where there is a concern about sparks igniting flammable solvents, vapors, liquids, dusts or residues. There are many standards and recommendations that have been published by OSHA (Occupational Health and Safety Administration) and NFPA (National Fire Protection Association) that advise the use of non-sparking tools in hazardous environments.

NOTE: It is important to assess each situation carefully and use the appropriate tools for the hazards that are present. In some cases, “non-sparking” tools may still be able to produce a spark. Contact the tool manufacturer, and the producer of the flammable material (for example) for recommendations and more information.

What are the hazards of both “sparking” and “spark-proof” tools ?

Both “sparking” and “spark-proof” materials can cause ignition. Two types of hazards are associated with tools manufactured of either material:

  1. Ignition by friction, with impact on each other or on other materials such as steel or concrete, in which an “ordinary” (mechanical or frictional) spark is generated. All tools can ignite flammable mixtures by sparks generated by friction or impact. Nevertheless, this is true only when a spark that has to have enough heat content (eg. enough mass and sufficiently high temperature)and last long enough to heat a flammable air-vapour mixture above its ignition temperature. This is more likely in the case of sparks formed when using a metal grinder than a spark generated when a hammer strikes some metal.
  2. Ignition by a chemically-generated spark: caused by impact between certain metals and some oxygen-containing substances (eg. rust).

How should you use and maintain “spark-proof” tools?

Follow the guidelines below to reduce the risk of explosion and fire.

  1. Make sure all “spark-proof” tools are kept away from ferrous or other contaminants, which may destroy the non-sparking properties.
  2. Do not use “spark-proof” tools in direct contact with acetylene, which may form explosive acetylides, especially in the presence of moisture.
  3. Use local exhaust or ventilation systems to remove hazardous materials, dusts and vapors from the workplace.
  4. Adhere to safety procedures when sharpening non-sparking tools, eg. the provision of eye and face protection, adequate extraction and dust collection facilities.

What is the best practices to safeguard against accidental explosions?

Follow safe work procedures, always evaluate a job to be done in a hazardous environment (even the simplest one)!

  1. Use proper tools and equipment that eliminate ignition such as electric motors that can be certified as “explosion proof” for use in most hazardous work locations or non-sparking tools with proper use and maintenance.
  2. Keep in mind that there are no truly non-sparking tools. In any work where flames are used, or sparks are produced, make sure that an explosive atmosphere does not develop. Such atmospheres include flammable vapour-air mixtures and organic dust clouds like flour or coal dust.
  3. Isolation, ventilation and purging are methods of insuring a safe working atmosphere.
  4. Use gas detector to monitor the lower explosive limit (LEL) of a workplace, stop work and evacuate immediately when it exceed.

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