A carabiner or karabiner is a metal loop with a sprung or screwed gate that is used to quickly and reversibly connect components in safety-critical systems. The word comes from "Karabinerhaken", meaning "hook for a carbine

Carbine

A carbine , from French carabine, is a longarm similar to but shorter than a rifle or musket. Many carbines are shortened versions of full rifles, firing the same ammunition at a lower velocity due to a shorter barrel length....

" in German

German language

German is a West Germanic language, related to and classified alongside English and Dutch. With an estimated 90 – 98 million native speakers, German is one of the world's major languages and is the most widely-spoken first language in the European Union....

.

Use

Carabiners are widely used in rope-intensive activities such as climbing

Climbing

Climbing is the activity of using one's hands and feet to ascend a steep object. It is done both for recreation and professionally, as part of activities such as maintenance of a structure, or military operations.Climbing activities include:* Bouldering: Ascending boulders or small...

, caving

Caving

Caving—also occasionally known as spelunking in the United States and potholing in the United Kingdom—is the recreational pastime of exploring wild cave systems...

, sailing

Sailing

Sailing is the propulsion of a vehicle and the control of its movement with large foils called sails. By changing the rigging, rudder, and sometimes the keel or centre board, a sailor manages the force of the wind on the sails in order to move the boat relative to its surrounding medium and...

, construction

Construction

In the fields of architecture and civil engineering, construction is a process that consists of the building or assembling of infrastructure. Far from being a single activity, large scale construction is a feat of human multitasking...

, and window cleaning. Carabiners used in sports tend to be of a lighter weight than those used in industrial rope work and rope rescue

Rope rescue

Rope rescue is a subset of technical rescue that involves the use of static nylon kernmantle ropes, anchoring and belaying devices, friction rappel devices, various devices to utilize mechanical advantage for hauling systems, and other specialized equipment to reach victims and safely recover...

. Carabiners can be made from steel

Steel

Steel is an alloy that consists mostly of iron and has a carbon content between 0.2% and 2.1% by weight, depending on the grade. Carbon is the most common alloying material for iron, but various other alloying elements are used, such as manganese, chromium, vanadium, and tungsten...

 or aluminium

Aluminium

Aluminium or aluminum is a silvery white member of the boron group of chemical elements. It has the symbol Al, and its atomic number is 13. It is not soluble in water under normal circumstances....

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Locking mechanisms

There are two broad categories of carabiner, locking and non-locking.

Non-locking

Non-locking carabiners have a sprung swinging gate that accepts a rope, webbing sling, or other hardware. Rock climbers frequently connect two non-locking carabiners with a short length of nylon web to create a quickdraw

Quickdraw

Quickdraws are used by rock climbers to connect the climbing rope to bolt anchors or other protection, while lead climbing...

.

Three gate types are common:

• Straight gate: The most utilitarian, and hence most popular.

• Bent gate: Curved gates allow for easier clipping in and out in special situations, such as connecting a rope to a quickdraw. Gate strength remains on a par with straight-gate carabiners.

• Wire gate: The lightest type, with a strength roughly equal to the others, allowing more to be carried for a given weight. Wire gates are less prone to icing up than solid gates, an advantage in Alpine mountaineering and ice climbing. The reduced gate mass makes their wire bales less prone to 'gate flutter,' a dangerous condition which momentarily opens the gate (and thus lowers the breaking strength of the carabiner) created by irregular impact forces generated by the rope itself or contact with hard surfaces in a fall.

Locking

Locking carabiners have the same general shape as non-locking carabiners but have an additional sleeve securing the gate. These sleeves may be either threaded or spring-loaded twist-lock.

• Twist-lock: May either be manually engaged or auto-locking. Auto-locking offer the advantage of engaging without user input. Being spring-loaded either type is prone to spring fatigue or their mechanisms becoming balky from dirt, ice, or other contamination. They are also difficult to engage one-handed.

• Screw-lock: Are threaded and must be engaged and disengaged manually. Fewer moving parts than spring-loaded mechanisms, less prone to malfunctioning, easier to employ one-handed. More effort and more time-consuming.

Shape

Carabiners come in four characteristic shapes:

• Oval: Symmetric. Most basic and utilitarian, also the least expensive. Smooth regular curves are gentle on equipment and allow easy repositioning of loads. Their greatest disadvantage is that a load is shared equally on both the strong solid spine and the weaker gated axis.

• D: Asymmetric shape transfers the majority of their load onto the spine, the carabiner's strongest axis. Slightly more expensive.

• Offset-D: Variant of a D with a greater assymmetry, allowing for a wider gate opening. More expensive yet.

• Pear/HMS: Specialized oversized offset-D's used in belaying. Most expensive and heaviest carabiner. Essential when using a Munter hitch
  Munter hitch
  The Munter hitch, also known as the Italian hitch, is a simple knot, commonly used by climbers and cavers as part of a life-lining or belay system. To climbers, this knot is also known as HMS, the abbreviation for the German term Halbmastwurfsicherung, meaning half clove hitch belay...
  
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Europe

• Recreation: Carabiners sold for use in climbing in Europe must conform to standard EN 12275:1998 "Mountaineering equipment - Connectors - Safety requirements and test methods," which governs testing protocols, rated strengths, and markings. A breaking stress of at least 20 kN (20,000 newtons = approximately 4,500 pounds of force which is significantly more than the weight of a small car) with the gate closed and 7 kN with the gate open is the standard for most climbing applications, although requirements vary depending on the activity.http://www.paci.com.au/Downloads/S-EN12275_simplified.pdf

Carabiners are marked on the side with single letters showing their intended area of use, for example, K (via ferrata

Via ferrata

A via ferrata or klettersteig is a mountain route which is equipped with fixed cables, stemples, ladders, and bridges. The use of these allows otherwise isolated routes to be joined to create longer routes which are accessible to people with a wide range of climbing abilities...

), B (base), and H (for belaying with an Italian or Munter hitch

Munter hitch

The Munter hitch, also known as the Italian hitch, is a simple knot, commonly used by climbers and cavers as part of a life-lining or belay system. To climbers, this knot is also known as HMS, the abbreviation for the German term Halbmastwurfsicherung, meaning half clove hitch belay...

).

• Industry: Carabiners used for access in commercial and industrial environments within Europe must comply with EN 362:2004 "Personal protective equipment against falls from a height. Connectors." The minimum gate closed breaking strain of a carabiner conforming with EN 362:2004 is nominally the same as that of EN 12275:1998 at around 20 kN. Carabiners complying with both EN 12275:1998 and EN 362:2004 are available.

United States

• Fall protection: Carabiners use for fall protection in US industry are classified as "connectors" and are required to meet Occupational Safety and Health Administration
  Occupational Safety and Health Administration
  The United States Occupational Safety and Health Administration is an agency of the United States Department of Labor. It was created by Congress of the United States under the Occupational Safety and Health Act, signed by President Richard M. Nixon, on December 29, 1970...
  
   standard 1910.66 App C Personal Fall Arrest System which specifies "drop forged, pressed or formed steel" construction and a minimum breaking strength of 5000 lbf (22.2 kN).

American National Standards Institute

American National Standards Institute

The American National Standards Institute is a private non-profit organization that oversees the development of voluntary consensus standards for products, services, processes, systems, and personnel in the United States. The organization also coordinates U.S. standards with international...

/American Society of Safety Engineers

American Society of Safety Engineers

Founded in 1911, the American Society of Safety Engineers is the oldest safety society and is committed to protecting people, property and the environment. Its more than 33,000 occupational safety, health and environmental professional members manage, supervise, research and consult on safety,...

 standard ANSI Z359.1-2007 Safety Requirement for Personal Fall Arrest Systems, Subsystems and Components, section 3.2.1.4 (for snap hooks and carabiners) is a voluntary consensus standard. This standard requires that all connectors/ carabiners support a minimum breaking strength (MBS) of 5000 lbf (22.2 kN) and feature an auto-locking gate mechanism which supports a minimum breaking strength (MBS) of 3600 lbf (16 kN).

• Rescue: Minimum breaking strength requirements and calculations for rescue carabiners are set out in National Fire Protection Association
  National Fire Protection Association
  The National Fire Protection Association is a United States trade association that creates and maintains private, copywrited, standards and codes for usage and adoption by local governments...
  
   standard 1983 Fire Service Life Safety Rope and Equipment. The standard defines two classes of rescue carabiners. Light use rescue carabiners are required to have minimum breaking stengths of 27 kN gate closed, 7 kN gate open and 7 kN minor axis. General use rescue carabiners are required to have minimum breaking stengths of 40 kN gate closed, 11 kN gate open and 11 kN minor axis. Testing procedures for rescue carabiners are set out in ASTM International
  ASTM International
  ASTM International, known until 2001 as the American Society for Testing and Materials , is an international standards organization that develops and publishes voluntary consensus technical standards for a wide range of materials, products, systems, and services...
  
  standard F 1956 Standard Specification of Rescue Carabiners.