Confined Space

Lesson 8: RESCUE EQUIPMENT

INSTRUCTIONAL GOAL

Upon completion of this topic, the student will understand the need to properly select and use -rescue equipment for confined space entry and rescue.

ENABLING OBJECTIVE

Based on the information presented in the classroom and in the student guide, the student will be able to:

1. Explain the uses and limitations of static kernmantle rescue rope. 2. Identify various rope rescue hardware components and explain their use. 3. Demonstrate the correct procedure for tying the following and hitches: a) Simple figure-8 b) Figure-8 on a knot c) Figure-8 follow-through knot d) Figure-8 bend e) f) Munter hitch g) Double fisherman‘s knot h) knot i) Butterfly knot

OVERVIEW This chapter provides information on different types of rope rescue equipment that can be used in confined space entry and rescue. Proper use and care of the equipment as well as any limitations that the user should be aware of will be covered.

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Rescue , W ebbing, and Equipm ent

The 1990 revision of the NFPA 1983 Standard on Fire Service Rope Life Safety Rope, Harness, and Hardware states that a life safety rope shall have a maximum working load of not less than 300 pounds for a one-person rope and 600 pounds for a two-person rope. It further states that the minimum breaking strength shall not be less than 4,500 pounds for a one-person rope and 9,000 pounds for a two-person rope.

Rope Strength

At first glance it may seem odd as to require a breaking strength of 4,500 pounds for a one-person rope. Common sense would indicate that a person would not be suspended on the rope with 4,500 pounds, but the possibility of the rope needing to withstand 4,500 pounds of force is a real possibility.

Force, simply defined, is anything that can cause a moving object to change its shape, change its direction of motion, and/or change the speed at which it is moving. As an example, you apply forces to your car when driving. Every time you step on the accelerator or the brake, you change the speed of your car. Likewise, when you a corner, you change direction. If you collide with something, you change the shape and speed or even direction of your vehicle. The force that causes these changes is called kinetic energy.

Kinetic Energy

Kinetic energy is expressed mathematically as KE = ² mv2 where m is the mass (weight) of the object and v is the velocity (speed) that the object is moving. It should be apparent that the larger the mass of an object, the more kinetic energy it will possess, assuming that the velocity remains constant. This is easy to see when comparing the stopping distance for a car traveling 60 mph with the stopping distance of a freight train traveling 60 mph. The relationship between mass and kinetic energy is a linear 1. That is, if the velocity is held constant and the mass is doubled, the KE is doubled; if mass is tripled, the kinetic energy is tripled, and so on.

Free-fall is different. An object in free-fall, such as when a person slips in a confined space vertical entry, will accelerate at a constant 32 feet per second for every second of fall (32 feet/second2) because of the force exerted by gravity. W hat this means is that acceleration changes the velocity, so the velocity is no longer constant. However, the mass of the falling object does remain constant. By looking at the mathematical expression for kinetic energy, KE = ² mv2, it should

≤HMTRI 2004 Page 50 Confined Space be noted that as velocity doubles, the KE quadruples (increases by four times) since the velocity in the expression is raised to the second power, or "squared" (v2). Subsequently, if the velocity triples, the kinetic energy increases by a factor of 9.

The following table shows the relationship between distance and time of free-fall and the kinetic energies generated:

Kinetic Energy Chart for a 160-Pound Falling Body

Height of Fall Time of Fall Velocity of Fall KE or Force of Impact (feet) (seconds) (feet/second) 2 (pounds)

10 0.80 25.6 1,638 20 1.10 35.2 3,097 30 1.40 44.8 5,017 40 1.60 51.2 6,553 50 1.78 56.9 8,410 60 1.95 62.4 9,732 70 2.10 67.2 11,287 80 2.25 72.0 12,960 90 2.38 76.1 14,477 100 2.50 80.0 16,000

As stated earlier, a rope must absorb the force of a falling object in order to stop its fall. According to the data table, it does not require much falling distance to generate 4,500 ft/lbs of force. A person weighing 160 pounds (not including equipment) in falling only 1.4 seconds would require a rope to withstand 5,017 ft/lbs of force. If this person fell 75 feet, a speed of nearly 50 mph would be attained and they would impact with a force of almost 6 tons!

Consider the act of jumping from a chair onto the floor with your knees locked and landing flat-footed. The jar or jolt received upon impact with the floor is rather large because the collision is non-elastic. In other words, the energy of impact was dissipated in a very short period of time. However, if the jump is repeated with knees bent and landing upon the balls of the feet, the impact jolt is reduced since the collision time is increased. It is for this reason that the dashboards of cars are made of foam rubber rather than steel. The "give" in the foam allows the force of the collision to be dissipated over a longer period of time, reducing instantaneous kinetic energy.

This same principle is applicable to rope work when friction devices or brakes are used to gradually slow a fall rather than stop it with a jolt. By lengthening the time of deceleration, the force that the rope must absorb at any one instant is kept fairly low. More importantly, ropes stretch. The NFPA Standard indicates that a lifeline breaking elongation shall not be less than 15 percent or more than 55 percent. Stretching the rope is another way of spreading the shock energy over a longer period of time. This advantage is not present in cable systems.

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W ork, Mechanical Advantage, and the Pulley

The pulley is one of six simple machines with particular application in confined space entry and rescue. Basically, the pulley is used to do two things: (1) change the direction of a rope‘s force, and (2) produce mechanical advantage. To understand the concept of mechanical advantage, one needs to look at the definition of work. In science, work is defined as the product of force and distance and can be expressed mathematically as shown here:

W ork = Force x Distance

For example, it takes force to push a refrigerator across the floor. The farther it is pushed, the more work it will take. If you have a 120-pound weight that needed to be lifted 2 feet, that would require:

W ork = Force x Distance = 120 lbs x 2 ft = 240 ft/lbs.

If you had a pulley attached just above the weight and a rope was strung through the pulley and attached to the weight, by pulling the rope 2 feet, you could lift the weight 2 feet. This would be equivalent to 240 ft/lbs of work. The pulley only changed the direction of the rope. It did not offer any mechanical advantage. Suppose that you now have a two- pulley system where one pulley is anchored above the weight, and the other pulley is attached directly to the weight. W hen the rope is pulled this time, the pulley attached to the weight moves. Moving pulleys provide mechanical advantage. In other words, the 120-pound weight will not feel as heavy because of the mechanical advantage that the moving pulley provides. How much lighter will it feel? Since you now have a 2:1 (pronounced two-to-one) mechanical advantage system, the weight will feel one-half as heavy. How can the presence of a moving pulley reduce the apparent weight of this object? The answer lies in the mathematical definition of work. Notice that if you raise the weight 1 foot using a 2:1 system, you will have to pull 2 feet of rope through the pulley system. So, to lift the 120-pound weight 2 feet, you will need to pull 4 feet of rope through the system. This is expressed mathematically as:

W ork = Force x Distance = 60 lbs x 4 ft = 240 ft/lbs

Note that you still had to supply 240 ft/lbs to lift the weight 2 feet. Consequently, no matter how you get it there, lifting the weight 2 feet is going to require the same amount of work. W hat is variable is how long you spread that work out. Instead of doing all of the work through 2 feet of rope, you do the work over twice the time. Therefore, you would only have to supply half the effort at any one time. It's like loading a piano into the back of a truck. You can apply a lot of force in a short time and lift it straight up or apply less force at any one time by using a ramp and spreading that same amount of work over a longer period of time. Likewise, if you build a 3:1 system you will cut the force needed at any one time by applying the force over a longer time.

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W ork = Force x Distance = 40 lbs x 6 ft = 240 ft/lbs

A 4:1 mechanical advantage rope system is very common in confined space entry and rescue. If a person weighs 200 pounds, his apparent weight will be 50 pounds. If that person has to be lifted 80 feet though, at least 320 feet of rope will be necessary. However, having that length of rope in a system virtually guarantees that the rope will twist and become tangled. Methods of applying mechanical advantage systems to single ropes will be covered in a later section.

Mechanical advantage also works in reverse. Suppose that a 4:1 mechanical rope system is being used. Furthermore, three healthy individuals pull on the rope. If one individual could pull with 100 pounds of force, three individuals could each pull with 100 pounds of force on the end of the rope for a total of 300 pounds of force being transmitted to the mechanical advantage system. That doesn't seem so bad. Suppose, however, that the person they were lifting became stuck and the people pulling the rope just kept on pulling. How much force would be applied to the entrant? Three hundred pounds of force magnified by a 4:1 system would result in 1,200 pounds of force being applied to the entrant! That's quite enough force to break bones and cause severe injury. For that reason, it is recommended that no more than two people pull on systems that are 4:1 or greater. The haul team (people who pull the rope) must be very sensitive to increases in rope load.

Rope Types / Properties

No one rope is perfect for all applications. Nylon rope has been the mainstay in rescue for years, but several new fibers are now available for confined space rescue. If you have special concerns, contact a reputable dealer.

ñ Nylon: Melts at 480 to 500°F. High strength. Resistant to caustics. Affected by some acids. Good abrasion resistance. Loses 10 percent strength when wet, regains strength when dry. Handles shock loading. Good ultraviolet (UV) resistance.

ñ Polyester: Melts at 480°F. Strength loss above 300°F. Less elastic and lower strength than nylon. Better resistance to acids than nylon. Affected by caustics. Good UV resistance. Good abrasion resistance.

ñ Polyolefin: Polypropylene melts at 225 to 270°F. Low strength. Poor abrasion resistance. Poor UV resistance. Impervious to acids. Not for rescue use.

ñ Spectra: Melts at 300°F. Strength loss above 150°F. Good UV resistance. Good abrasion resistance. Good resistance to most chemicals. High strength. Low elongations. Poor shock loading.

ñ Kevlar: Chars at 600°F. High strength. Poor abrasion resistance. Poor shock loading. Does not handle sharp bends.

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Rope Construction Types

Kernmantle: Core (kern) - Braided sheath (mantle). Core provides 50 to 85 percent of strength. Mantle 15 to 50 percent of strength.

Static Kernmantle (Low stretch): Desired in most rescue applications. Two percent stretch with a 200-pound load; 3 to 4 percent stretch with 900 pounds of load; 20 percent stretch at failure. Should not be used if fall factor is greater than 1. Fall factor above 0.3 can cause injury. (Fall factor is the number of feet of fall divided by the number of feet of rope between the anchor and the falling body.)

Dynamic Kernmantle (High stretch): Desired in applications with high fall factors; 35 to 45 percent stretch at failure. Not recommended for raising and lowering rescue systems. These ropes are designed to absorb fall factors greater than 1.

Double : Braid of rope inside a second braided rope. Not common in rescue ropes. Some fire departments use this type. A new multi-fiber rope of this design is available.

Standards and Organizations

OSHA has no standard for rescue ropes other than a 5,400-pound 6-foot fall safety lanyard standard. The National Fire Protection Association (NFPA) has a written standard on rope rescue and related equipment. Consequently, it is best to consult with reputable vendors regarding ropes and rope utilization and to follow the NFPA recommendations:

Static Kernmatic Rope

ñ 15:1 safety factor. ñ W orking load of 300 pounds per person. ñ One-person load rope strength of 4,500 pounds with a rope size of 3/8 to 7/16 inches. ñ Two-person load rope strength of 9,000 pounds with a rope size of one- half inch. ñ Rope used in an actual rescue must be new and unused.

Rope Care and Storage A written history should be kept on all ropes. This will ensure that all ropes are within the recommended specifications for use. All ropes should be protected from UV light (sunlight), hydrocarbons, chemicals, high temperatures, and dirt. Storage should be in a cool dry place.

Training Ropes Training ropes should be inspected after each use. This inspection should be visual as well as by feel. Any rope should be retired after five years, after being involved with a 5-foot fall, if sheath penetration occurs, or soft spots develop in the core. The ropes can still be

≤HMTRI 2004 Page 54 Confined Space used, but not for rescue or rescue training. Store training ropes in rope bags and prevent exposure to chemicals. W hen in doubt, throw it out.

The question is, "W hat to use?“ W hen possible, nylon static Kernmantle is the rope of choice. The following is a list of various rope types available:

D/d NFPA Type Material Strength Ratio Certified Kernmantle 100% Nylon ²" 9,000 lbs 4:1 Yes Kernmantle Polyester sheath, nylon ²" 9,000 lbs 4:1 Yes core Kernmantle 100% Polyester ²" 9,000 lbs 4:1 Yes Double Polyester cover ²" 15,800 lbs 8:1 No Braid Kevlar/Spectra core

W ebbing

W ebbing is utilized for rigging, anchors, and to tie harnesses. W hile several types are available, one-inch tubular is the most common. Other types of webbing construction include: ñ Nylon 1" tubular (spiral weave) 4,000 lbs. ñ Nylon 1" solid type 18 flat 6,000 lbs. ñ Nylon 2" tubular 6,000 lbs.

It is important to note that tubular webbing will not withstand shock loading and has poor abrasion resistance.

Prusik Cord

Prusik cord is another type that consists of a 7 to 9 mm nylon cord with 2,000 to 3,000 pounds strength. It is used for tie-offs, prusik lines, and substitute ascenders. Again, it is important to note that this material will not withstand shock loading.

Carabiners

Carabiners are metal links used in joining gear with gear or a person with gear. These links are designed to be loaded on the long axis and not designed for double axis load. Strengths vary depending upon the type of carabiner.

Several types of carabiners are available in varying strengths and sizes. Aluminum carabiners have a breaking strength of up to 6,500 pounds and are designed to handle a one-person load. Steel carabiners have a breaking strength of up to 12,000 pounds and are designed to handle a two-person load. Steel carabiners are generally preferred in rescue situations. All carabiners used in rescue operations should be designed to lock the gate shut to prevent the gate from opening while the rescuer is on-line.

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It is important to not over-tighten the carabiner latch or to tighten the latch while it is under a load. Doing so will make it almost impossible to loosen the latch later. If a carabiner is dropped over 5 feet to a hard surface, it must be replaced. The integrity of the carabiner cannot be guaranteed unless tested.

Triangular Screw Links (Tri-Links)

Rescue tri-links are triangular-shaped metal screw links used in place of carabiners when three-way loading is expected to occur. Rescue screw links are specially designed with a large gate opening to accommodate rope up to 5/8“ in diameter. The tri-link is also a compact lightweight alternative to carabiners for semi-permanent attachment. The tri-link is constructed of galvanized or stainless steel and has a breaking strength of at least 9,900 pounds. Links are marked with a normal working load, (NW L), which is about one-fifth of their breaking strength.

Figure-8 W ith Ears

A figure-8 with ears is an aluminum or steel descender device used for lowering or rappelling. The strength is 9,000 to 11,000 pounds and is intended for short lowerings only. The ears are designed to prevent an unloaded rope from slipping over the sides of the large hole and forming a girth hitch, thereby locking the figure-8 to the rope when loaded again. Many rescue groups prefer descenders with ears to lock off the rope and help prevent the rope from slipping. Limitations include no variable friction capability and its use causes twists and kinks in rope.

Ascenders

An ascender is a mechanical coming device used to ascend a fixed rope. It can also be used as a haul and safety cam in rescue systems. There are two types of ascenders: handled ascenders (not for rescue use) and cam ascenders. Brand name cam ascenders currently on the market are the Gibbs and Rescuecender.

Cam ascenders grab one-fourth to one-inch of rope when used. They can damage or destroy the rope if overloaded. Strengths vary from 2,500 to 6,000 pounds. Gibbs are pull-tested to 1,000 pounds. An important note is that cam ascenders cannot catch a load in a dynamic belay situation and ascenders will cause the rope to fail at less than one- third of the rope's strength.

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Prusik Knots

Some agencies prefer doubled triple-wrap prusik knots in place of safety cams and single triple-wrap prusik knots in place of haul cams. W hen comparing ascenders and prusik knots, both have strengths and weaknesses.

Strengths

ñ Inexpensive. ñ Simple to tie. ñ Can be used to ascend or descend loaded and unloaded ropes. ñ Can be used for self-rescue. ñ Can be use to assist hoisting and hauling when mechanical- advantage systems are stacked or piggybacked

W eaknesses

ñ Can be difficult to slide or untie after load has been placed on it. ñ Must be small diameter cord. ñ May slip in wet or icy conditions.

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Pulleys

The pulley is a simple machine that has a particular use in permit space entry and rescue. Pulley construction consists of metal wheels, side plates, and bearings. W hen sizing pulleys, use a 4:1 ratio as a minimum. (That means that if a one-half inch rope is used, the diameter of the pulley should be at least four times as large or, in this case, 2 inches.)

A pulley is a type of lever. It can be fixed in one spot or be movable. A pulley makes work easier by changing the direction of applied force or producing a mechanical advantage.

Rescue Harness Harnesses are the link by which a person is connected to the rescue or retrieval system. NFPA places harnesses into three categories:

ñ Class I a) Fastens around the waist b) Designed for one-person load c) Common ladder belt ñ Class II a) Fastened around waist and thighs or under buttox b) Rapelling seat ñ Class III a) Fastens around waist, around thighs or under buttox, and over shoulders b) Used when inverting is possible c) Recommended for confined space entry and rescue d) D-rings provide at least 5,000 pounds of strength

Full-Body Harness

Other body designs will work but are uncomfortable when hanging. Harnesses need attachment points at the front waist and center back. Remember, no one harness can meet the needs of every situation.

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Helm ets

A critical piece of PPE is the helmet. Select a helmet with a four-point suspension system, substantial construction, and little or no brim. Standard construction hard-hats do not provide adequate protection, while fire helmets are too bulky for confined space entry and rescue.

Gloves

Proper gloves should be worn at all times during a rescue. Leather gloves are best for rope work. It is important to remember that leather cannot be decontaminated should exposure occur.

Fall Protection and Retrieval Equipm ent

Make certain that the equipment used is rated for a life-safety load. Some are designed for equipment use only. Always follow the manufacturer‘s instructions for equipment utilization.

Tripods are rated for a one-person load (350-pound working load and 5,000-pound break strength). They are designed to evenly load all three legs, so it is important to ensure the legs are stable before using. Always use a safety chain to secure the legs when in use.

Cable winches are used for lowering/retrieval and arresting falls. Some winches are not designed for life-safety loads. If a winch is used for lowering, separate fall protection must be provided. W inches usually have a 350-pound working load.

Cables are utilized in retrieval and lowering systems. A 3/16" cable has a 350- pound working load. Cable breaking strength varies from 3,700 to 4,200 pounds depending upon the cable type. Cable lacks the ability to absorb shock; thus, the shock loading ability is built into the winch system.

Lanyards, when used, should allow no more than 6 feet of fall. They need a break strength of 5,400 pounds and should be replaced after one fall.

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Knots

There are many knots and variations of knots that can be and are used in rescue and rescue systems. The knots discussed and demonstrated here are basic for confined space entry and rescue. The major concepts surrounding knots are: 1. Tie it. 2. Dress it. 3. Tighten it. 4. Secure it with safety knot.

The following knots are recommended for personnel to become familiar with and competent in tying. Proficiency is obtained only by practice and use.

ñ Simple figure-8 knot ñ Figure-8 on a bight knot ñ Figure-8 follow-through ñ Clove hitch ñ Munter hitch ñ Bowline ñ Butterfly knot ñ Square knot

Simple Figure-8 Knot

The basic knot for the figure-8 group is the simple figure-8. The simple figure-8 is easy to recognize because of its distinctive "8" shape. Use this knot as the basis for more complex figure-8 knots. The simple figure-8 is frequently used as a "stopper" knot. W hen rigging a rope through hardware, tying a simple figure-8 in the top end of the rope will help prevent the rope from accidentally running out through the equipment.

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Figure-8 on a Bight Knot

The figure-8 on a bight forms a non-slip loop in the rope and is usually used for clipping the rope to something. The figure-8 on a bight is frequently used to attach a rope to a rescue harness by attaching the loop to a locking carabiner and then attaching the carabiner to the harness D-ring. This knot can also be used to attach a rope to an anchor where there is already an anchor with a carabiner attached.

After you have tied the knot, "dress" it. W hen dressing a knot, work the knot so the strands are parallel to one another. Then compact the knot by pulling all the strands tight. Make certain enough tail is left at the end of the rope so that it doesn‘t pull through when loaded. Many rescuers like the added security of tying a safety knot, such as an or a . The single or double overhand knot should be tied close to the main knot.

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Figure-8 Follow-Through

The figure-8 follow-through is used to tie a rope directly to an anchor or directly to a harness. Tying a simple figure-8 in the rope end and leaving about three feet of rope on the end does this. Take the short end of the rope and thread the rope back through the simple figure-8 knot, retracing it back all the way. Finish the knot off with an overhand safety knot to prevent the figure-8 from accidentally untying.

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Butterfly Knot

The butterfly knot is used primarily to tie a non-slip loop in the middle of a rope. This knot may be loaded in different directions without significant distortion (and weakening) of the knot.

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Bowline

The bowline knot is used primarily to make a fixed (non-slip) loop in the end of a line.

This knot should always be secured with an overhand safety knot tied on the loop formed by the bowline.

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Double Fisherman's Bend

The single fisherman's bend lays two lines parallel to each other but pointing in the opposite direction, then forms a double overhand knot with each end around the standing part of the other line. Pulling on the standing parts jams the two knots against each other. For the triple fisherman‘s bend, take an additional turn toward the inside of the knot before tucking in the working end.

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Clove Hitch

The clove hitch is primarily used to attach a rope to a pole or rod. This knot only secures when under tension. An overhand safety knot should always be tied to prevent it from untying. Because it passes around an object in only one direction, it puts very little strain on the rope fibers.

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Munter Hitch

The munter hitch is used as a belay device for a person suspended by rope. Belaying is the incorporation and manning of a separate safety line connected to a rescuer via an independent anchor. The munter hitch is designed to arrest and hold a one-person load in the event of a main-line system failure.

In almost all rescue work, this will be a top belay in which the belayer will take in or play out rope in time with the ascent or descent. The belayer ensures that as little slack as possible develops between the belay device and the load but will be careful not to inhibit free movement of the load by keeping the belay too tight. If a belay line is under continual load, it is no longer a belay but a lowering line.

Square Knot

The square knot is used to tie the ends of a rope together. A square knot can be loosened after it has been under tension. The square knot is not a secure knot, and overhand safety knots should be tied on each side of it to prevent it from being accidentally untied.

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Ring Bend (W ater Knot)

The ring bend is one of the few bends suitable for use in flat material such as webbing. The bend is begun by tying a simple overhand knot in one end of the webbing. The second running end is then traced back over the first knot in such a manner that the ends finish facing away from each other.

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