Take a Powder: PATs

Powder-actuated tools (PATs) are common at virtually every job site. A PAT is a nail gun used to join hard materials, such as steel, masonry and concrete. PATs are based on technology referred to as “direct fastening,” which uses a controlled explosion that is created by a small chemical propellant charge. This process is very similar to how the technology used to discharge a firearm functions.

PATs are classified according to several criteria. In the direct-acting tool, the charge acts on the head of the fastener; indirect action uses an intermediate piston to hit the fastener. The charges are loaded into the tool singly or magazine-fed on a plastic strip. Also, charges can be automatically or manually fed.

PATs are convenient for attaching materials that are difficult to join. This convenience comes at a price: these tools can be extremely dangerous, even lethal, if not handled correctly.

Due to this heightened level of danger, the Occupational Safety and Health Administration (OSHA) requires that anyone using a PAT be trained and certified on the particular tool. All qualified operators are required to carry a valid certification card. A large portion of the training for PAT certification involves safety. This is imperative because a PAT is a potentially lethal weapon.

Australia takes this threat so seriously that PATs are classified and controlled as firearms. In the United States, two types of certification are available, depending on where PAT users live. California has its own requirements, and the certification is good for three years. The other 49 states have a common certification that lasts a lifetime.

It is crucial that even those certified and experienced in using PATs take time to read and understand the operating instructions. These will remind the user of the correct way to handle the tool, fastener length, what types of base materials are too hard or soft, and the correct way to determine powder load. Reading the operation manual could prevent improper usage and serious injuries. There are some general safety rules when using a PAT that, when followed, will ensure everyone’s safety.

First, the loads PATs use have a very precise amount of a special powder to sustain a consistent driving speed for the fastener. The powder level of the charge is designated by color, which is coded according to the velocity at which they fire. The colors are ranked from lowest velocity to highest as follows: gray, brown, green through yellow, red and purple. The owner’s manual is an excellent resource to determine the appropriate color and level powder load. As a rule of thumb, the harder the base material, the more powder is needed.

Before firing the PAT, it is important to know the thickness and type of base material present and to test the fastenings, starting with the lowest powder level. When there is a possibility that the base material may chip, such as with concrete, or spark, such as with steel, it is important to use a spall shield to help reduce injury from those results.

When ready to load the PAT to start fastening, it is important to insert the fasteners into the tool before the powder load. A PAT should never be loaded until it is needed, and a loaded PAT should never be left unattended.

PAT safety features have been built in to help prevent injuries. One such feature is that the tool cannot be fired unless the muzzle is compressed against the work surface and until the sliding action of the barrel stops. This will prevent the PAT from firing into anything other than the desired surface.

Additional safety tips include the following:

• American National Standards Institute/OSHA-approved eye and ear protection and a hard hat must always be worn when operating a PAT.

• When loading or handling the tool, always point it away from your body or face.

• Never put any part of the body in front of the muzzle.

• Be certain that the work area is clear on all sides.

• Be certain that the work area is posted with warning signs to notify coworkers and bystanders that a PAT is in use.

• Always unload a PAT before disassembling, assembling, replacing the barrel or cleaning the tool.

• Never carry fasteners or other hard objects in the same pocket or container with powder loads.

• When the PAT is not in use, it should be unloaded and locked in the storage container with the charges.

Although some of these safety precautions may be seen as excessive and time-consuming, they are more than made up for by the convenience of the PAT and having all employees leave the job site safely.

KELLY is a safety and health specialist with Intec, a safety consulting, training and publishing firm that offers on-site assistance and produces manuals, training videos and software for contractors. She can be reached at 800.745.4818 and dkelly@intecweb.com. Joe O’Connor edited this article.

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