Chapter 7: Ropes and knots Flashcards
life safety rope:
designed to be used only for rescue and other emergency operations
o also used to raise, lower or support firefighters during training
o should not be used for any other purpose
NFPA 1983
specifies that only rope of block creel construction using continuous filament virgin fiber for load bearing elements is suitable for life safety applications
block creel construction
method of manufacturing rope without any knots or splices; a continuous strand of fibre runs the entire length of the ropes core
In order to be reused in life safety situations, the standard also requires that ropes met the following criteria:
o No abrasions
o No exposure or heat or direct flame
o No exposure to any impact load
o No exposure to the liquids, solids, gases,mists or vapours of any chemical or other material that can deteriorate rope
Remove a life safety rope from service if
it has been subjected to an impact load, fails inspection, has been used only as utility rope, or is marked for destruction
Life safety rope that has been converted to utility rope is referred to as
downgraded
rope log
Start and keep a rope log throughout the ropes working life
Utility Rope
can be used to hoist equipment, secure unstable objects or cordon off an area
- NFPA does not have standard s
- Inspect utility rope regularly to see if its damaged
Synthetic fibers
are used to construct both life safety and utility ropes while natural fibers are only permitted for utility ropes
The main difference between syntetic and natural fibers ropes is
the material used for the construction, which affects the use and longjevity of each type of rope
Synthetic ropes are replacing natural ropes as utility ropes because
natural fibrer rope loses its strength when it gets wet and rots rapidly
Synthetic fibers include:
o Polypropylene
o Nylon
o Kevlar
o Polyester
o Polysteel
o Spectra
A disadvantage of synthetic fibers
is that they will melt when exposed to heat
Synthetic fiber rope has the following advantages;
o Excellent resistance to water, mildew, mold, rotting and shrinkage
o Longer life span than natural fibre rope
o Lightweight yet very strong
o Easy to maintain
Most natural fiber rope is made from
plant fibers such as:
o Manila
o Hemp
o Sisal
o Cotton
natural fibre rope should not be used for
Should not be used for life safety applications
natural fibre disadvantages
-Prone to mildew and mold
-Deteriorates when exposed to chemicals and It burns
Natural fiber rope does have the following advantages
o More resistant to sunlight than synthetic rope
o Chars rather than melts (fails) when exposed to heat
The most common types of rope construction are
o Kernmantle
o Braided
o Laid
o Braid on braid
Kermantle rope
jacketed synthetic rope composed of a braided covering or sheath (mantle) over a core (kern) of the main load-bearing strands
kermantle core
- The core strands run parallel with the rope’s length and work in conjunction with the covering to increase the ropes stretch resistance and load characteristics
- The core is made of high fibers usually nylon which accounts for 75% of the total strength of the rope
kermantle rope sheath
The sheath protects the core from abrasions and contamination
Comes in both ______ and _______ types
Comes in both dynamic (high stetch) and static (low stretch) types
Dynamic rope and advantages
is used when long falls are a possibility
o To reduce the shock of impact in falls, dynamic rope is designed to stretch without breaking
dynamic rope disadvantage
when trying to raise or lower heavy loads, dynamic rope is not used for hoisting applications other than as belay line
Static rope
is used for most rope-rescue operations
o It is designed for low stretch without breaking
o Used for rescue, rappelling and hoisting where falls are not likely
NFPA 1983 low stretch rope must not elongate more than ____ when tested under a load equal to ____ of its breaking strength
NFPA 1983 low stretch rope must not elongate more than 10% when tested under a load equal to 10% of its breaking strength
Laid ropes
are constructed by twisting fibers together to form strands then twisting the strands (typically three) together to make the final rope
- Used exclusively as utility ropes
One disadvantage of laid ropes is
that they are susceptiple to abrasion and other physical damage
o Damage also immediately affects the ropes strength
One advantage of laid (twisted) rope
this strand exposure is that it makes laid ropes easy to inspect
Braided rope
constructed by uniformly intertwining strands of rope together in a diagonally overlapping pattern
- Used as utility rope
- Most braided ropes are synthetic
advantage and disadvantage of braided rope
It is less likely to twist during use than laid rope but its load bearing fibers are still vulnerable to direct abrasion and damage
Braid on braid rope:
consists of a braided core enclosed in a braided sheath
- Braid on braid rope has a braided core running the length of the rope
- Very strong
- Half its strength is in the sheath and the other half is in the core
- Used as utility rope
A disadvantage of braid on braid rope is
that it does not resist abrasion as well as kermantle rope
o The sheath may slide along the inner core of rope
Double braided rope is sometimes confused with
kermantle
Personnel should inspect all ropes when?
after each use and inspect unused rope at least once a year
If any of the following damage is found, remove the rope from service and have it destroyed:
o Imbedded shards of glass
o Metal shavings
o Wood splinters
o Foreign objects that can damage the fibers
Inspecting kermantle rope for damage is somewhat difficult because
the damage may not be obvious
- When inspecting put a slight tension on the rope while feeling for lumps, dpressions, or soft spots
o Soft spots are caused by bends of knots
o If you feel a soft spot inspect the outer sheath; if the sheath is damaged, the core is probably damaged as well
- If there is any doubt about the ropes integrity, it should be removed from service, downgraded to utility status or destroyed
In addition to inspecting kermantle rope for damage to the core and sheath, inspect the rope for:
o Irregularities in shape or weave
o Foul smells
o Discoloration from chemical contamination
o Roughness
o Abrasions
o Deterioration (fuzziness)
Rope that is excessively fuzzy in one spot or overall should be removed from service
Synthetic laid rope
should be untwisted so that all the sides of each strand can be inspected
- Mildew must always be removed, after which the rope should be cleaned and reinspected
When inspecting synthetic rope look for the following:
o Sift, crusty, stiff or brittle spots
o Cuts, nicks or abrasions
o Dirt or grease
o Excessive stretching
o Chemical damage
o Other obvious flaws