Nail gun injuries occur in the hand and fingers, and more than one-quarter of these situations involve structural damages to tendons, joints, nerves and bones. Nail gun injuries can also be found in legs, knees, foot and toes. Although less frequent, some of these injuries have led to paralysis, brain damages, bone fractures and deaths. OSHA has developed a guide applicable to nail guns, emphasizing on framing nail guns. Framing nail guns usually tend to fire the largest nails, being considered the most dangerous and powerful nail guns.
Nail Gun: Triggers
Nail gun safety can be increased if the employee knows about the different types of trigger mechanisms. These mechanisms vary depending on the order in which the controls are activated and whether the trigger can discharge multiple nails of just single acting release mechanism. The different nail gun triggers are described in the following paragraphs.
Nail Gun: Full Sequential Trigger
This is the safest type of nail gun trigger. This trigger will only fire a nail when the controls are activated in a certain order. Also known as single-shot trigger, restrictive trigger, or trigger fire mode.
Nail Gun: Contact trigger
A nail gun with a contact trigger, fires a nail when the safety contact and trigger are activated in any order. Also known as bump trigger, multi-shot trigger, successive trigger, dual-action, touch trip, contact trip, and bottom fire.
Nail Gun: Single Sequential trigger
Like the full sequential trigger, this trigger will only fire a nail when the controls are activated in a certain order.
Nail Gun: Single Actuation trigger
Like the contact trigger, this trigger will fire a single nail when the safety contact and trigger are activated in any order. A second nail can be fired by releasing the trigger.
Nail Gun: Safety Precautions
These six practical steps contractors should take to prevent nail gun injuries. These are:
- Use full sequential trigger nail guns;
- Provide training;
- Establish nail gun work procedures;
- Check lumber for knots, straps or hangers that can affect the nail gun process;
- Always use your dominant hand when operating the equipment;
- Provide personal protective equipment (PPE);
- Use clamps to brace instead of your hands;
- Encourage reporting and discussion of injuries and close calls; and
- Provide first aid and medical treatment.
Nail Guns: Major Risk Factors
The most common risk factors that can produce a nail gun injury are:
- Unintended nail discharge from double fire. Occurs with CONTACT triggers. Double fire can be a particular problem for new workers who may push hard on the tool to compensate for recoil.
- Unintended nail discharge from knocking the safety contact with the trigger squeezed. Occurs with both contact and single actuation triggers. Holding or carrying contact trigger or single actuation trigger nail guns with the trigger squeezed increases the risk of unintended nail discharge.
- Nail penetration through lumber work piece. Occurs with ALL trigger types. Nail penetration is especially a concern for placement work where a piece of lumber needs to be held in place by hand.
- Nail ricochet after striking a hard surface or metal feature. Occurs with ALL trigger types. When a nail hits a hard surface, it has to change direction and it can bounce off the surface, becoming a projectile.
- Missing the work piece. Occurs with ALL trigger types. Injuries may occur when the tip of the nail gun does not make full contact with the work piece and the discharged nail becomes airborne.
- Awkward position nailing. Occurs with ALL trigger types. Unintended discharges are a concern in awkward position work with contact and single actuation triggers. Nailing in awkward positions where the tool and its recoil are more difficult to control may increase the risk of injury.
- Bypassing safety mechanisms. Occurs with ALL trigger types. Bypassing or disabling certain features of either the trigger or safety contact tip is an important risk of injury.