INTRODUCTION

 

CARABINERS ARE THE SINGLE MOST USEFUL ITEM you’ll use for work at height. No one has ever regretted having some extras on hand. As a window cleaner, you’ll use them for anchoring, descending, your back up line, and tons more. But, how do they work? What should be looking for when you decide what carabiners to purchase? This guide will answer your carabiner questions.

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SHAPE


OVAL

LET’S START SIMPLE with some of the different shapes carabiners come in! These shapes will include the Oval, D, and Pear shape. The oval shaped carabiner fits nicely into the any size hand allowing easy opening, and it also prevents shifting when loaded. One drawback is that the Oval shape is smaller, and will not be able to carry as much as some of the larger carabiners.

D Shaped

D Shaped

THE D SHAPED CARABINER IS LARGER and has a wider gate opening than the Oval. This shape is the “standard” carabiner. This will pair well with any decent device, and is most commonly used.


Pear

THE PEAR SHAPED CARABINER (aka the “Offset D”) will have an extra-large gate opening. You can use this carabiner to anchor several ropes or other gear together, which is very handy! These Pear shaped carabiners can sometimes be more difficult to operate, especially if you have smaller hands.

 

LOCKING MECHANISM

 

CARABINERS CAN ALSO BE CATEGORIZED by their locking mechanisms. The two main types are Screw Gate and Auto-Locking. There are also a few exotic ones that can’t really be categorized but are super cool.


Screw Gate

SCREW GATE OR “MANUAL LOCKING” CARABINERS will need to be manually twisted to open and shut the gate. Many people prefer Screw Gate carabiners because they like manually locking the carabiner themselves rather than relying on an automatic mechanism. Screw Gate carabiners are popular with recreational users and fire departments. In some countries they are also popular with rope access technicians.

Screw Gate

Auto-Locking

AUTO-LOCKING OR “SELF-LOCKING” CARABINERS will automatically close when the gate is released. They are available in non-locking (open) double locking (twist-open), and triple locking (pull-twist-open). ISC even offers a quad-locking carabiner… but for 99% of applications that just excessive. Double locking carabiners are by far the most popular because they are easier to operate, especially when wearing gloves. Non-locking carabiners should only be used for non-critical applications. Auto-Locking carabiners are popular in industrial work such as tower climbing and rope access.


Specialty

THERE ARE ALSO SOME SPECIALTY GATE OPENINGS. Petzl makes the Ball-Lock (which sounds really painful!). It has a small button that you push in to open the gate. Rock Exotica makes the Orca Lock which is half triple-lock and half non-lock. You can make the gate stick in the non-lock position so that it can be easily clipped onto things. Then once the gate opens and closes it automatically switches back to triple locking.

Specialty
Black Diamond Magnetron

Magnetron

AND THEN THERE’S THE BLACK DIAMOND MAGNETRON (awesome name, right?). Its locking mechanism uses magnets. It’s the coolest carabiner you’ll ever hold. It’s not rated for industrial use unfortunately, but still worth checking out. You can find one at REI.

 

Material


MANUFACTURERS HAVE CREATED CARABINERS out of different materials (mostly steel and aluminum). Which one you choose is based on weight and environmental considerations. Out of these types steel is going to be the strongest and most durable especially if you’re getting stainless steel (which holds up well in corrosive environments). But steel is also very heavy compared to aluminum. Aluminum carabiners are much lighter than steel, but not as strong.

Screw Gate

 

LATCH TYPES

 

There are a variety of latch types that secure your gate when its closed. The best is keylock because it is smooth and avoids snagging. Few things are more annoying than having a carabiner snag on something while you are trying to remove it.

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  • claw  
  • pin and notch 
  • keylock  
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LET’S TALK CERTIFICATION! The ANSI Z359 Standard will require an auto-locking carabiner that is marked and rated as being able to hold 5,000 pounds on the major axis, and 3,600 pounds on the minor axis/gate rating. The ANSI standard applies to industrial fall protection applications. This is the most applicable standard for window cleaning. Unless you have a good reason, you should use ANSI rated carabiners for window cleaning.

 

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FOR NFPA 1983 RATED CARABINERS you have NFPA T (formerly L for light) and NFPA G. Light use carabiners must have a major axis breaking strength of 27kn (6069lbf). Whereas General use carabiners must have a major axis breaking strength of 40kn (8992lbf). NFPA T is for lighter “technical” loads while NFPA G is for heavier “general” loads. NFPA would apply for fire, electrical, and building safety. 

 

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FOR SPRAT (SOCIETY OF PROFESSIONAL ROPE ACCESS TECHNICIANS) SAFE PRACTICES WOULD BE:

 

“Carabiners and similar connectors with screw-gates or self-locking methods of closure are the only types that can provide the required level of security for this type of work. If used to clip onto steel cable, shackles or eye bolts, they should be constructed of steel or other suitably hard metals. Those that are to clip to any anchorage (e.g., hanger, eye bolts, or shackles) should be of such a design and size that they can rotate freely in them without hindrance and without loosening the anchorage. Minimum strength: 22 kN (5,000 lbs)” SPRAT Safe Practices August 2, 2012 Edition

 

SPRAT guidelines are followed by highly trained rope access technicians. They are best practices, but are less stringent than ANSI Z359 in their carabiner requirements.

If you are working in an industrial setting, make sure you are using ANSI rated gear, or that you are prepared to coherently explain to OSHA why you aren’t. 

 

PROPER USE

OF COURSE WITH ANY PIECE OF EQUIPMENT you want to make sure you are using your hardware properly. If used incorrectly you can reduce the overall strength of the carabiner, and even bend or break the hardware.

 

Your carabiner is much stronger on the major axis, which is where you will want any load hanging from. Whenever you have a load that isn’t on the major axis, that’s called cross-loading. Make sure to avoid cross-loading your carabiner by loading in the correct position, with the gate facing you to prevent your gate from opening.

 

Always make sure that your gate is fully closed before using it. Even Auto-Locking carabiners can “stick”, so double check before hanging on them.

carabiner
 
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  • claw  
  • pin and notch 
  • keylock  
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HOW CARABINERS ARE MADE

 

How are carabiners made? To find out we talked to Rock Thomson, the founder of Rock Exotica and maker of the coolest hardware around.

 

Q: Can you describe how carabiners are made?

A: There are quite a few steps.

  1. Start with Aluminum rod in T0 Condition. That means it’s soft, which is important because we need to ben it.
  2. Chop it off to length.
  3. Bend it. We use constant pressure which yields consistency.
  4. Put it into a press. This puts it into the shape we want and adds any graphics.
  5. Heat treat it. We use a two step process. This hardens the metal and makes it stronger.
  6. Hardness test. We want to make sure all the carabiners are the proper hardness.
  7. Break some samples. We break about 1% of each batch at this stage to make sure they are proper strength.
  8. Machine them. We have to add some holes such as the rivet hole for the gate.
  9. Tumble them. They are put into a large container of beads to smooth off any rough edges.
  10. Anodize them.
  11. Machine gate and sleeve from solid rod.
  12. Tumble gate and sleeve.
  13. Assemble pieces. We put the body, gate, and sleeve together.
  14. Rivet them together.
  15. Test to half rated strength. We test every carabiner to half its rated strength to make sure it will perform properly. We’ve never had one fail out of hundreds of thousands, except when the gate wasn’t closed properly before testing.
  16. Straighten if necessary. We want to make sure every carabiner that leaves Rock Exotica operates smoothly.
  17. Laser Mark.
  18. Final Inspection.

Q: How are carabiner strengths determined?

A: By breaking them. We test our carabiners internally, and send them out to a CE lab for certification. We also use UL labs for NFPA certification.

In most cases we are testing to the breaking point, not deformity. So, a carabiner can start to bend before it’s actually broken.

Q: How much variance in strength will you see from one carabiner to another in the same batch.

A: Usually up to 5%. A lot of it has to do with where the pins in the tensile tester go exactly. Sometimes they aren’t perfectly on the major axis and you’ll see the strength go down a bit.

 

Thanks to Rock for lending his expertise!

 

And speaking of strength, what’s three sigma? UL labs and others use three sigma to determine the final strength that is printed on the carabiner. It is a statistical model where you break a number of carabiners, determine the average, and then move three standard deviations below that. This means that 99.87% of carabiners will be at least as strong as what’s stamped on the side.

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