Revisiting Pneumatic Nail Gun Trigger Recommendations

Abstract

Use of a pneumatic nail gun with a sequential actuation trigger (SAT) significantly diminishes the risk for acute traumatic injury compared to use of a contact actuation trigger (CAT) nail gun. A theoretically-based increased risk of work-related musculoskeletal disorders from use of a SAT nail gun, relative to CAT, appears unlikely and remains unproven. Based on current knowledge, the use of CAT nail guns cannot be justified as a safe alternative to SAT nail guns. This letter provides a perspective of ergonomists and occupational safety researchers recommending the use of the sequential actuation trigger for all nail gun tasks in the construction industry.

Figure 1

The full sequential actuation trigger (SAT) nail gun is safer because it requires that the two controls be actuated in a specific sequence. First the safety tip is pressed against the lumber (left panel), then the trigger is depressed to fire the nail (middle panel). When the nail gun fires, recoil of the tool away from the workpiece (right panel) can result in a second, unintended, contact of the safety tip. With the SAT a nail will NOT fire on the second contact of the safety tip because the trigger must first be released and then actuated after the safety tip. Conversely, a contact actuation trigger (CAT) fires with the controls actuated in either sequence and the trigger need not be released between successive nails fired. With a CAT nail gun unintended firing occurs when the tool is held or positioned with the trigger pressed and the tip inadvertently contacts the body or other object.

Figure 2

It is natural and more efficient to grip a tool handle with a full power grip, which includes use of the index finger in the grip. With most nail guns the index finger must actuate the trigger to contribute to the grip of the tool, as shown above.