Hotwire Questions and Answers
Chris Harmston
Diamond has received about the Hotwire, its properties, and testing we
have conducted. This post is in response to more of these same questions
and is not intended as advertisement in any way. If anyone has questions
about this message, about unanswered Hotwire issues, or any quality
related issue with Black Diamond equipment please contact me directly.
Chris Harmston
Quality Assurance Manager
chr...@bdel.com.
August, 1995
Fellow climbers:
Thanks for your interest in the HotWire Carabiner. The questions we've
been sent via mail and e-mail about the HotWire show that many climbers
are curious about how this unique biner works. We are glad that you
don't take your gear for granted and want to know more. This flyer
addresses the most frequently asked questions about the HotWire, and
clarifies some common misconceptions about its unusual design. Black
Diamond would like to hear any additional comments you might have.
Contact us at:
Black Diamond Equipment, Ltd.
2084 East 3900 South
Salt Lake City, UT 84124 USA
Phone: (801) 278-5533; Fax: (800) 775-7625;
E-Mail: cl...@bdel.com
Why is the HotWire so strong?
There are two basic reasons: body shape and gate material. The HotWire's
body is designed so that a significant percentage of its mass is
concentrated at the nose--the most common breaking point for biners--to
give the HotWire its superior 25 kN closed-gate strength. The HotWire can
afford to have a thicker, stronger nose and still maintain its light
weight due to the negligible mass of the gate itself. The body's
cross-section design gives the HotWire its open-gate strength; at 10 kN,
few biners can rival it.
Unlike conventional carabiners, the HotWire's gate is not aluminum. The
gate wire is made of stainless spring steel which significantly exceeds
the strength of an aluminum gate.
Is the wire gate as strong as a conventional gate when it is
cross loaded?
It's not just as strong, it is stronger. When a conventional carabiner
gate is cross loaded beyond its strength it will break, causing total
failure of the biner. At the load where aluminum gates start failing,
the HotWire's gate will have already bent but remains an intact "closed
loop." Although the HotWire gate may deform at a lower cross load than a
conventional biner, the force which finally causes the HotWire to fail is
about 20% greater than the failure load for conventional biners.
We test the HotWire's minor axis strength by applying a load
perpendicular to the gate, pulling the biner apart between two 12-mm pins
or between a pin and a climbing rope. Out of the one hundred-plus
HotWires we have pulled to failure in a cross-load configuration, none
have failed because the gate wire broke. In fact, in cross-load tests
the HotWire is stronger than any other carabiner that Black Diamond
makes.
HotWires easily surpass the updated UIAA and CEN standards which require
carabiners to have a minimum 7 kN strength along the minor axis. But
it's not only the rating that's important; the method used to establish
the rating is just as relevant to a biner's strength. By using the Three
Sigma Rating System we establish ratings which are extremely
conservative. This means that the 7 kN minor axis rating we give the
HotWire is a significantly lower number than what our tests indicate the
actual cross-load strength is. (Contact us for a copy of our Spring 1995
Catalog or our Carabiners Pamphlet if you'd like more information on the
Three Sigma System.)
Could the gate of the HotWire damage a rope?
The possibility of shredding your rope if it should cross load a
carabiner's gate is sobering. Cross loading any carabiner is very
dangerous, both for the biner and the rope, and should be avoided at all
costs. Refer to our Carabiners Pamphlet for advice on carabiner use.
We performed a series of tests cross loading HotWires with a 10-mm rope,
to measure the effects that the wire gate had on climbing ropes. We
preformed similar cross-load tests on regular carabiners for comparison.
The gate wire itself does not cause rope damage, although most types of
biners caused moderate rope damage near their breaking points.
Carabiners can, in extremely rare instances, slice a rope sheath if the
biner is cross loaded. Because the HotWire's gate is a smooth continuous
loop, the absence of interruptions or sharp edges on the wire gate can
actually help to prevent rope damage.
What is the expected longevity of the gate and its spring action?
The wire is the strongest part of the carabiner; the body will fail
before the wire gate will break. With a 25 kN closed gate Three Sigma
rating, the HotWire is among the strongest carabiners ever designed. To
test the integrity of the gate-spring action, we measured the gate force
of several samples of HotWires on our Carabiner Test Machine, then cycled
them on a fatigue test station which repeatedly opens and closes the
gates. After testing the samples with more than 300,000 cycles, we
remeasured the samples on the Carabiner Test Machine, which showed no
measurable change in gate-spring action or failure strength. The wire
gate's action will not wear out or weaken under normal use.
How effectively do HotWires prevent "whiplash" (carabiner gate oscillation)?
Whiplash is a sudden opening of a rope-carrying carabiner's gate in
reaction to a sudden force, such as when the biner is loaded by a fall,
or if it slams against the rock. On very rare occasions, this
instantaneous opening of the gate can result in carabiner failure, if the
biner is loaded at the precise moment the gate is open. The low mass of
the HotWire's gate helps to eliminate whiplash, as does its stiff gate
action. By using high speed photography, we observed how HotWire gates
reacted to sudden forces. The wire gates proved to be much less
susceptible to whiplash movement, where conventional biner gates
oscillated substantially more.
Can HotWires be used on both ends of a quickdraw?
Yes. The gate's flat surface makes clipping the rope into the HotWire as
easy as clipping a bent-gate biner. The HotWire can also be used for
clipping bolts, pro, anchors (doubled up and opposed of course) and for
all other general carabiner uses. Any biner which clips easily can also
be prone to unclipping; take precautions to prevent situations where this
could happen.
If your quickdraws have HotWires on both ends, we recommend that you use
one end exclusively for clipping the rope and use the other end just for
clipping bolts. Why? As you've probably noticed, on regular quickdraws
with one bent gate and one straight gate biner, the straight-gate biner
gets worn on the inside from the bolt hanger. Everyday wear on the
inside of the biner body does not affect strength, but can create small
edges that could damage a rope. This applies to HotWire carabiners too.
If your quickdraws have HotWires on the top and bottom, we suggest you
mark your draws to identify which is the bolt-clipping biner.
Are HotWires just for sport climbing?
HotWires are for ALL types of climbing: long gear routes, sport climbs,
ice, mountaineering, aid. The HotWire's testing has included extensive
field use with both prototype and production models. Their performance
out of the lab has been nothing short of excellent across the spectrum of
climbing environs. Alpine climbers appreciated a super-strong,
lightweight biner that wouldn't freeze up due to its one piece
gate/spring mechanism. HotWires were also popular with aid climbers and
long-route aficionados for their versatility and minimal
weight.
Are there any applications in which HotWires should not be used?
We do not recommend that you use HotWires to make a carabiner-brake
rappel. You won't break the biner, but you could bend the gate,
rendering the biner unusable in the future.
Does taping around the gate improve the biner?
We don't recommend that you tape the gate. Wrapping tape around the gate
wire restricts the spring action of the gate. The two legs of the wire
work independently against each other to act like a spring; when they
cannot move freely, the gate action is compromised.
Chris Harmston (chr...@bdel.com)
Quality Assurance Manager/Materials Engineer
Black Diamond Equipment Ltd.
2084 East 3900 South, SLC, UT 84124 phone: 801-278-5552