A powder-actuated tool (PAT, often generically called a Hilti gun or a Ramset gun after their manufacturing companies) is a type of

nail gun A nail gun, nailgun or nailer is a form of hammer used to drive nails into wood or other materials. It is usually driven by compressed air (pneumatic), electromagnetism, highly flammable gases such as butane or propane, or, for powder-actuate ...

used in construction and manufacturing to join materials to hard substrates such as steel and concrete. Known as ''direct fastening'' or ''explosive fastening'', this technology is powered by a controlled explosion of a small chemical propellant charge, similar to the process that discharges a firearm.

Features

Powder-actuated tools are often used because of their speed of operation, compared to other processes such as drilling and then installing a threaded fastener. They can more easily be used in narrow or awkward locations, such as installing steel suspension clips into an overhead concrete ceiling. Powder-actuated tools are powered by small explosive cartridges, which are triggered when a firing pin strikes a primer, a sensitive explosive charge in the base of the cartridge. The primer ignites the main charge of powder, which burns rapidly. The hot gases released by the burning of the propellant rapidly build pressure within the cartridge, which pushes either directly on the head of the fastener, or on a piston, accelerating the fastener out of the muzzle. Powder-actuated tools come in high-velocity and low-velocity types. In high-velocity tools, the propellant charge acts directly on the fastener in a process similar to a firearm. Low-velocity tools introduce a piston into the chamber. The propellant acts on the piston, which then drives the fastener into the substrate. The piston is analogous to the bolt of a

captive bolt pistol A captive bolt (also variously known as a cattle gun, stunbolt gun, bolt gun, or stunner) is a device used for stunning animals prior to slaughter. The goal of captive bolt stunning is to inflict a forceful strike on the forehead with the bo ...

. A tool is considered low velocity if the average test velocity of the fastener is not in excess of with no single test having a velocity of over . High-velocity tools may not be made or sold in the United States; however, some made decades ago are still in use in the shipbuilding and steel industries. Powder-actuated fasteners are made of special heat-treated steel; common nails are unsafe for this application. There are many specialized fasteners designed for specific applications in the construction and manufacturing industries.

History

Powder-actuated technology was developed for commercial use during the

Second World War World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposi ...

, when high-velocity fastening systems were used to temporarily repair damage to ships. In the case of hull breaches, these tools fastened steel plates over damaged areas. These tools were developed by Mine Safety Appliances, for the United States Navy. Powder-actuated tools were investigated and used prior to this development; they were used in

anti-submarine warfare Anti-submarine warfare (ASW, or in older form A/S) is a branch of underwater warfare that uses surface warships, aircraft, submarines, or other platforms, to find, track, and deter, damage, or destroy enemy submarines. Such operations are t ...

during the First World War and were the subject of a 1921 United States patent (US Patent No. 1365869).

Types

file:Ramset-gun.jpg, A Ramset powder actuated fastener tool and supplies. The colored straws in the tray contain cartridges that are loaded singly into the tool. Also visible are 75 mm hardened steel nails with 8 mm heads. Powder actuated tools can be variously classified: * Direct acting (the charge acts directly on the head of the nail or high velocity), or indirect (using an intermediate piston or low velocity) * Single-shot, or magazine-fed * Automatic or manual piston cycling * Automatic or manual feed of the charges

Energy sources

Strip-fed cartridges for a nail gun Powder-actuated tools are powered by specially-designed blank firearm cartridges, also informally called "loads", "boosters", "rounds", or "charges". In many cases, the charges are ordinary firearm cartridges with modified casings, and the bullets omitted. The

.22 Short .22 Short is a variety of .22 caliber (5.6 mm) rimfire ammunition. Developed in 1857 for the first Smith & Wesson revolver, the .22 rimfire was the first American metallic cartridge. The original loading was a bullet and of black powd ...

, developed by Smith & Wesson, is common. These charges may be hand-fed (single-shot), or manufactured and distributed on a plastic carrier strip.

Color coding

Fin-stabilized rounds, one fitted with an orange-colored sabot Yellow sabot near the tip of the round The three single-shot strengths or colors typically sold to the general public are brown, green, and yellow in brass-colored casings. Not all powder-actuated tools are rated for high-capacity charges—the strongest charge (nickel-purple at ), for example, is dangerous in a tool not rated for the high pressures it generates. The table above is for a slug from a test device.

Safety and regulation

As with their air-actuated cousins, powder-actuated guns have a muzzle safety interlock. If the muzzle is not pressed against a surface with sufficient force, the firing pin is blocked and cannot reach the load to fire it. This helps ensure that the gun does not discharge in an unsafe manner, causing the nail to become an unrestrained projectile. Due to their potential for causing personal injury,

OSHA OSHA or Osha may refer to: Work * Occupational Safety and Health Administration, a federal agency of the United States that regulates workplace safety and health * Occupational Safety and Health Act (United States) of 1970, a federal law in the Un ...

regulations in the US require certification specific to the tool being used before any person is permitted to rent or use powder-actuated equipment. Most manufacturers of powder-actuated nail guns offer training and certification, some with free online testing. In addition, special instruction is necessary if the prospective user is unable to distinguish colors used in the color code system that identifies proper power levels. Most certifications are accepted for life; however, in California they must be renewed every three years. The ownership and use of these tools is regulated in Australia. The owner has to register the tool, and an operator of one of these tools is required to have a license and to have undergone training in their use. These laws are in keeping with Australia's extremely strict

firearm laws Gun laws and policies, collectively referred to as firearms regulation or gun control, regulate the manufacture, sale, transfer, possession, modification, and use of small arms by civilians. Laws of some countries may afford civilians a right t ...

References

{{refs Mechanical hand tools