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Q&A: Energy Absorber Systems and Safety Lines

Friday, September 28, 2018

READER QUESTION: 
Is an energy absorber system needed on the safety line to help limit the impact forces should the belay system be engaged to arrest the falling load?

ROCO TECH PANEL ANSWER: 

Thank you for your question. Roco uses traditional untensioned safety lines in most all of our rescue systems, and we do indeed incorporate an energy absorber (shock) in those belay systems. While OSHA does not address specifics when it comes to rescue systems, there is some overlap from the OSHA as well as the ANSI standards that is helpful when considering the belay system during rescue. 

NFPA 1006 Standard for Technical Rescue Personnel Professional Qualifications, sections 5.2.9 through 5.2.11, provides guidance for the construction of a belay (safety line) system. Specifically, the 5.2.11 objective statement calls for the belay system to ensure “the fall is arrested in a manner that minimizes the force transmitted to the load.” The annex information to 5.2.9 adds: “A.5.2.9 Belay systems are a component of single-tensioned rope systems that apply a tensioned main system on which the entire load is suspended and a non-tensioned system with minimal slack (belay) designed, constructed, and operated to arrest a falling load in the event of a main system malfunction or failure. 

While these traditional systems used for lowering and raising are in common use, two-tensioned rope systems can also be used to suspend the load  while maintaining near equal tension on each rope, theoretically reducing the fall distance and shock force in the event of a singular rope failure. To be effective, two-tensioned rope systems must utilize devices that will compensate appropriately for the immediate transfer of additional force associated with such failures.”

Additionally the NFPA 1006 definition of belay is “3.3.9* Belay. The method by which a potential fall distance is controlled to minimize damage to equipment and/or injury to a live load.” And Annex information “A.3.3.9 Belay. This method can be accomplished by a second line in a raise or lowering system or by managing a single line with a friction device in fixed-rope ascent or descent. Belays also protect personnel exposed to the risk  of falling who are not otherwise attached to the rope rescue system."

So, where can OSHA help in all of this? OSHA requires the maximum force of a fall arrest system not to exceed 1,800 pounds. ANSI is more protective and requires arresting forces not to exceed 900 pounds. NFPA does not state what the arresting forces need to be limited to, but the performance measurement is to “minimize damage to equipment and/or injury to a live load.” OSHA and ANSI have already done the homework on this and stated their performance requirements. One proven way to meet NFPA 1006 as well as OSHA and ANSI requirements is to incorporate an energy absorber in the belay (fall arrest) system. Whether 1,800 pounds or the ANSI required 900 pounds is appropriate, or if you use a two tensioned system, this is up to your AHJ. 

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Inspection Process for Roco Training Ropes

Tuesday, August 28, 2018

Question: We recently had a student ask how our training rope is monitored for wear and tear because of its extensive use...

Answer: Good question, and it’s a big job for us, no doubt. We’ve used and inspected a lot of rope in the past 35+ years, but this aspect of life safety can never be overlooked or taken lightly. As always, we urge everyone to carefully follow the care, use and inspection guidelines provided by their rope manufacturer. For added safety and as standard practice, we also use secondary back-up ropes and hardware in all field activities. 

Because we train thousands of students per year, we must accept the fact that there are numerous opportunities for our ropes to be exposed to wear such as being stepped on or exposed to dirt and gravel. It is for these reasons that we perform rigorous inspection of the ropes before and after use. Plus, we also conduct an annual competent person equipment inspection as recommended by NFPA.

As added safety, we also expect our students to do their part in monitoring the equipment during a class, and that’s why we’re glad you brought this up.
We teach and enforce rope care and inspection of all equipment, including ropes, in all of our classes. Inspections are accomplished at multiple times during any given class including during inventory. Additionally, all equipment is inspected by a Roco employee at the conclusion of each class. If there are any signs of damage or degradation that would render the rope unserviceable according to the manufacturer’s instructions for use, that rope will be taken out of service.

Of course, we’ve seen some rope damaged over the years, which is to be expected with the use our rope receives. However, to my knowledge, we’ve never had a rope failure. We’ve seen cut sheaths and sheath slippage, evidence of broken core fibers, and other damage that failed the rope inspection. But, not once, have we had a rope fail while it was being used to support a life load. The construction and the minimum breaking strength requirements of life safety rope provide a very substantial margin of safety. And, there again, we also have the redundancy of a back-up system in place.

All manufacturers of life safety rope are required by NFPA 1983 (2017 edition) to provide the following inspection criteria information in their instructions for use:

(1) Rope has not been visually damaged.
(2) Rope has not been exposed to heat, direct flame impingement, or abrasion.
(3) Rope has not been subjected to impact load.
(4) Rope has not been exposed to liquids, solids, gasses, mists, or vapors of any chemical or other material than can deteriorate rope.
(5) Rope passes inspection when inspected by a qualified person following the manufacturer’s inspection procedures both before and after each use.

The following inspection tips are provided by PMI Life Safety Rope:

HOW TO INSPECT YOUR ROPE

LOOK AT IT.... ALL OF IT!
Start at one end and look at every inch of the rope. Watch for signs that might indicate possible damage such as discoloration, chemical odors, abrasion, cuts or nicks in the outer sheath and visible differences in the diameter of the rope in one area in relation to the rest of the rope.

WRAP IT IN SMALL LOOPS AND LOOK!
Wrap the rope around your hand to form small loops at different random points along the ropes length. Look at these small loops as you make them, the consistency of the loop should be uniform throughout. If it’s not, you might have a problem with the rope’s core.

FEEL THE ROPE!
While you are looking at every inch of the rope, run it through your bare hands and feel it for changes that might indicate damage to the core. Changes may include any inconsistencies in rope diameter, soft or “mushy” spots, or extraordinarily stiff areas.

WRITE IT ALL DOWN!
Write the results of your inspection on the Rope Log included with your rope. Be sure to include anything you found in your inspection that might be or become a concern and document other important information about the rope such as an occurrence of uncontrolled or excessive loading, rope older than 10 years, contact with harmful chemicals, and history of use.

IF IN DOUBT, THROW IT OUT!
If you are not sure about the integrity of a rope........DON’T USE IT!
Consult the manufacturer if you need help.

So, thank you again for asking about the rope used continuously in our training programs. Even with our many years of experience, we do not take rope safety margins as a license to misuse our ropes. And that is why we are diligent in caring for and inspecting all of our equipment including the ropes. 

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Why Use a High-Point Dorsal Connection Point?

Friday, July 06, 2018

We recently had a Facebook inquiry about attaching a rappeler's belay line (safety line) to their high-point dorsal connection on their harness. We choose to do this for a number of reasons including: (a) compliance with applicable regulations; (b) adherence to safe and practical rescue procedures; and, (c) the physiological effects of falls – how the body absorbs an impact force. Let’s take a general look at these considerations.

Compliance

OSHA considers our rappel/lower main lines as “work positioning” lines and our belay or safety lines as “fall protection.” The fact that they and we, as rescuers, consider the safety line as fall protection, or more accurately as our Personal Fall Arrest System (PFAS), kicks in a few requirements and considerations for all private sector responders and for municipal responders governed by OSHA-approved State Plans. These responders are required to comply with applicable OSHA regulations.

However, keep in mind, these regulations are designed to protect workers (and rescuers) from harm and injury. During training, since it is not a real rescue, we should be following the applicable regulations and standards for safety as well as liability reasons. Even during actual rescues, it is important to adequately protect our people from injury. The days of “rescue at all costs” are gone. We are responsible for designing training, systems and SOPs/SOGs that protect our people in a rescue situation.

Note the following key points from OSHA 1926.502(d):

• Limiting the free fall distance (max free fall 6 feet)
“…be rigged such that an employee can neither free fall more than 6 feet (1.8 m), nor contact any lower level”

• Deceleration distance of 3.5 feet (41 inches)
“…bring an employee to a complete stop and limit maximum deceleration distance an employee travels to 3.5 feet (1.07 m)”

• Maximum allowable impact load 1,800lbf.
“…limit maximum arresting force on an employee to 1,800 pounds (8 kN) when used with a body harness”

• Improvised anchorage strengths of 5,000lbf or twice the anticipated load.

“Anchorages used for attachment of personal fall arrest equipment shall be…capable of supporting at least 5,000 pounds (22.2 kN) per employee attached…”
“Have sufficient strength to withstand twice the potential impact energy of an employee free falling a distance of 6 feet (1.8 m), or the free fall distance permitted by the system, whichever is less.”

• Harness attachment should be to the high-point dorsal connection point.

“The attachment point of the body harness shall be located in the center of the wearer's back near shoulder level, or above the wearer's head.”

You may have heard the statement, “Firefighters/rescuers don't need fall protection or need to follow OSHA.” This is not true for the 27 State Plan states where OSHA regulations do apply to public sector employees including emergency responders. It puts the burden on the employer, agency or department to establish fall protection and rescue protocols that would adequately protect their people.

To illustrate this, here is an excerpt from an article written by Stephen Speer, a NY career firefighter, for “Fire Rescue” magazine which deals with potential OSHA violations during rescue operations and training exercises. (Note: New York is a State-Plan state.)

“I spoke to a New York State Public Employee Safety & Health (PESH) supervisor about the following scenario and asked if there were areas that could be potential violations.

Scenario: A firefighter operating from a roof ladder is cutting a ventilation hole on a pitched roof. The firefighter falls from the roof and is injured.

In what areas, if any, could an incident commander or company officer be cited? In response, I received 12 pages of documentation. The documents showed that in evaluating potential violations of the general duty clause to see if anyone is responsible, the following four elements must be met:

1. The employer failed to keep the workplace free from a hazard to which employees of that employer were exposed.
2. The hazard was recognized.
3. The hazard was causing or likely to cause death or serious physical harm.
4. There was a reasonable and adequate method to correct the hazard.

NFPA 1500, chapter 8.5.1.1, states that operations should be limited to those that can be completed safely. In this scenario, there is the potential for citation if all four elements apply. As the above scenario illustrates, whether or not you have an aerial apparatus, you must consider fall arrest protection.”

Practicality

When rescuers are sent into a vertical confined space, we use the safety line (PFAS) to protect them as they are being lowered and raised from the space. It is also used as “an immediate means of retrieval” should something go wrong inside the space. Having the safety/retrieval line attachment point at the high-point dorsal position allows us to attempt an emergency retrieval with the victim being extracted in a low profile to fit through a narrow portal.

Physiological Effects

There have been numerous studies on the effects on the body when subject to a fall and arrest while in a harness. They generally come to the same conclusion that high-point dorsal attachment is the most survivable and provides for the greatest injury reduction. Here are excerpts from two studies.

1) Excerpt from a study conducted by Dr. M. Amphoux entitled, “Exposure of Human Body in Falling Accidents,” which he presented at the International Fall Protection Seminar in 1983:

In experiments on the position of the attachment point on the harnesses, Amphoux found that a high attachment point was preferable because “it gave a better-disposed suspension” and that it was “especially effective when the attachment is on the back. When the falling stops, the neck flexes forward. If the attachment point is in the front of the sternum, the neck flexes backwards and the lanyard may strike the face.”

Amphoux continued that it would be better for the compression to be localized on the body of vertebrae and not on the posterior joints, which were too fragile. “Therefore,” he said, “the attachment point would be better on the back than pre-sternal and should be high enough to reduce the potential neck injury. In addition, the forward flexion would be stopped by the thrust of the chin on the chest.”

This was why Amphoux and his colleagues strictly recommended attachment high on the back. It also protected the face from the lanyard when falling. In the case of falling head first, regaining a feet-first position would involve flexion of the head, whereas if the attachment were pre-sternal, the head would more often be projected backwards [whiplash effect].

However, it was accepted that a front attachment might be preferred in a few working situations. This was only acceptable when the height of the potential fall was very short. Whatever the choice of body support, it should not be forgotten that it was only a compromise and not a guarantee of absolute security.

2) Excerpt from “Survivable Impact Forces on Human Body Constrained by Full Body Harness,” HSL/2003/09 by Harry Crawford:

The one-size-fits-all policy of some harness manufacturers may not be suitable for the range of body weight 50kg to 140kg. Although it may be possible for those in the wide range of body weight/size to don such a harness, the position of the harness/lanyard attachment is of paramount importance. For best performance and least risk of injury, the attachment should be as high as possible between the shoulder blades.

Note: They also concluded that the shorter the fall, the less impact and less chance of injury no matter which type of harness or where the connection point was.

Conclusion

Like any rescue or work safety technique, you need to look at all the variables and decide which technique and equipment will best protect you or your co-workers. We choose the high-point back connection because of the variety of situations and locations we might face during a rescue based on the three considerations mentioned earlier in this article.

Thanks for a great question and taking the time to look into the reasons why systems or techniques are used. I hope this answers your question. If you have additional questions, please contact me at 800-647-7626.

By Dennis O'Connell, Roco Director of Training

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Job Assignments and Rescue Duties

Wednesday, May 02, 2018

QUESTION: Should industrial rescue team members be informed of any scheduled confined space entries at the beginning of their shift?

ANSWER: While OSHA does not mandate that individual team members be notified; common sense and best practices do. Here’s our reasoning for encouraging this “information sharing” at the beginning of each shift.

First of all, it is the Entry Supervisor’s responsibility to ensure that the rescue service is available prior to each PRCS entry. This verification should be performed in a way that confirmation of availability can be documented. There are various reasons that the in-house team may not be immediately available, so it’s up to the Entry Supervisor to plan ahead and coordinate with the team. Most often in-house industrial rescue team members have regular job assignments in addition to their rescue duties. Depending on the particular assignment, he or she may or may not be available to respond to a rescue emergency. In fact, we have heard of incidents where the Entry Supervisor just “assumed” that because the facility had an in-house rescue team that the team would always be ready to respond. In one instance when an in-house team was notified of a PRCS emergency, only one (1) team member was on shift and available to respond. Apparently, other team members were on sick leave, vacation, or at shift change. As you can see, two-way communication between the Entry Supervisor and the rescue service is a must!

Having a system in place that allows on-duty team members to be aware of PRCS entries that are scheduled during a given shift allows them to start the preplan process, which will help reduce response and preparation times. It also provides Team Leaders (IC) with a better understanding of possible rescue needs and how best to utilize available resources if an emergency situation should arise. And, these are just some of the reasons we recommend that on-duty team members be accounted for and be made aware of any entries occurring during their shift - including the location, the type of entry and the hazards involved. It simply provides for better preparation; thus, making everyone safer.

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Calculating Compound M/A

Tuesday, June 13, 2017

We recently had a request for additional information beyond what was shown in our “Theory of Mechanical Advantage” video by Chief Instructor Dennis O'Connell. The reader would like to know more about calculating compound mechanical advantages.

First of all, a simple mechanical advantage (MA) is quite easy to calculate as long as you follow a couple of basic rules.

MAs are generally expressed in numeric ratios such as 2:1, 3:1, 4:1, etc. The second digit of the ratio, or the constant "1" represents the load weight. The first digit, or the variable 2, 3, 4, etc. represents the theoretical factor that we divide the load weight by, or inversely multiply the force we apply to the haul line.

I say theoretical as these calculations do not take into account frictional losses at the pulleys and resistance to bend as the rope wraps around the pulley tread. So a 3:1 mechanical advantage would make the weight of a 100-pound load feel like 33 pounds at the haul line, but we do lose some advantage due to those frictional losses. An even more important consideration is the fact that we multiply our hauling effort by the variable, which is important to understand when we think about the victim or an on-line rescuer that has become fouled in the structure. This is also important when considering the stresses on the haul system including the anchor, rope, and all components in the system.

We also need to pay attention to the amount of rope that must be hauled through the system to move the load a given distance. If we are using a 4:1 MA and need to move the load 25 feet, we need to pull 100 feet of rope through the system (4 X 25 feet = 100 feet).

To calculate a simple MA, remember this: if the anchor knot is at the load, it will be an odd mechanical advantage (3:1, 5:1, 7:1, etc.). If the anchor knot is at the anchor, it will be even (2:1, 4:1, 6:1, etc.) “even/anchor-odd/load.” And if you count the number of lines coming directly from the load, you will determine the variable (remember not to count the haul line if it passes one final change of direction pulley). For instance, if the knot is at the anchor and there are four lines coming from the load, this will result in a 4:1 simple MA. And if your haul line is being pulled away from the anchor, that only means you have created one final change of direction which oftentimes is done to allow the addition of a progress capture device (ratchet), or simply to make it a more convenient direction of pull. But this 5th line, called the haul line, does not come directly from the load. It comes from the final directional pulley to the haul team and is not to be counted in the simple MA ratio. We would call this set up a 4:1 MA with a change of direction (CD).

Calculating compound MAs is also quite easy. Compound MAs (sometimes called a stacked MA) simply means we are attaching a second MA to the haul line of the original MA. When we do so, we multiply the first digit of the original MA by the first digit of the second MA. If you attach a 2:1 MA to the haul line of a 4:1 MA (2 X 4 = 8), you end up with an 8:1 compound MA. Keep in mind that we have added even more frictional losses into this system, but it is still a pretty powerful MA.

There are potential benefits as well as potential penalties when using compound MAs. One benefit includes using less gear when stacking MAs. For instance, to build a simple 6:1 MA, you will require at least five pulleys, and if you want a final CD, that would require one last pulley for a total of six pulleys. If you decide to build a 6:1 compound MA, you can get away with as few as three pulleys by attaching a 2:1 MA to the haul line of a 3:1 MA. If you wanted one final CD, you would again add one more pulley for a total of four pulleys. The obvious advantage is that fewer pulleys are required, but hidden in there as another advantage is fewer pulleys for the rope to wrap which translates to less frictional loss and bend resistance.

Another benefit to stacking MAs may be the reach you need to attach to the load. If the load is 25 feet away from the anchor and you are using a 6:1 simple MA, you will need at least 150 feet of rope, plus some extra to tie the anchor knot, and some spare to wrap over the final directional - if you use one. If the load is 50 feet below the anchor and you want to stick with the simple 6:1 MA, you are looking at a minimum of 300 feet of rope.

So, what if we send a 3:1 MA down from the anchor to the load 25 feet below and attach a 2:1 to the haul line of the original 3:1 to build a 6:1 compound MA?

Well, in this case we would need 75 feet of rope plus some extra for knots for the original 3:1, and two times the length of the compounding MA throw. Throw? What the heck is throw? Throw is a term we use when we have a limited distance between the compounding MA anchor and where we can safely attach the compounding MA to the haul line of the original MA.

In the diagram below you can see the original 3:1 MA extending from its anchor to the load. The added MA, which in this case is a 2:1 has a total throw of 10 feet which requires a little over 20 feet of rope to construct. So, if we add the 75+ feet of rope required for the original 3:1 to the 20+ feet for the added 2:1, we arrive at a bit over 95 feet of rope required for this compound 6:1 MA to reach a load 25 feet from the anchor. This can be two separate ropes, one a bit over 75 feet and a second a bit over 20 feet, or it can be one rope a bit over 95 feet that we can treat as if they were two separate ropes. More on that in a bit.



Remember that we must consider the amount of rope that we need to pull through the system in order to move our load the required distance. So, using a 6:1 compound MA to move the load 25 feet we must pull a total of 150 feet of rope through the system. Whoa, wait a minute! I thought we determined that our total rope needs were only a bit over 95 feet, so how did we come up with 150 feet of rope? One of the disadvantages of compound MAs is the need for resets when the throw is not long enough to move the load the needed distance. So, even though we are using in the neighborhood of 95 feet of total rope, we are pulling the same section of rope through the second MA multiple times.

Well, this is one of the big disadvantages of a compound MA. We need to reset the system multiple times to move the load the required distance. To help envision a reset cycle, let’s assume we have our original 3:1 mounted to an anchor, and 25 feet from that anchor is the 3:1 attached to the load. The haul line of the original 3:1 goes through a final CD, and we have attached a ratchet at that final CD to capture the progress of the loads movement. One option is to find a second anchor and in this case we found one 10 feet away from the final CD of the 3:1. We tie an anchor knot and attach it to that second anchor and route the remaining 20+ feet of rope through a pulley which we attach to the haul line of the original 3:1 with a rope grab. We now have our 2:1 pulling on the haul line of a 3:1 resulting in a 6:1 compound MA.  But…… and there’s always a “but,” isn’t there? We can only move the load a bit over 3 feet at a time before we completely collapse the 2:1 and need to reset it for the next haul. Remember, the 2:1 only has a 10-foot travel or “throw” and that distance is divided by 3 as it is pulling on a 3:1 MA. In addition to that, we have pulled about 20 feet of rope through the 2:1 just to move the load a bit over 3 feet. In order to move the load the entire 25 feet we will need to reset the system about 8 times and that is some slow going. Just to point out one option to speed up the haul by reducing the amount of resets needed, if you sent the original MA to the victim as a 2:1 and then stacked a 3:1 MA with 10 feet of throw onto that 2:1, you would still have your compound 6:1 but would only need to do about 5 resets and could do it with a bit over 80 feet of rope.




There are all sorts of options when deciding what type and ratio of MA to use in a rescue effort. You can get pretty creative when building MAs, but be aware that creativity can sometimes lead to crazy. Remember the KISS principle…keep it simple and safe.

If you are overbuilding an MA just to show a cooler way of doing it, you may be missing the point of the job. There is someone in trouble that is relying on you getting them up and out of their predicament, and sometimes we can get a little carried away with our creativity, especially when it comes to MAs. 3:1 Z-rigs are a great option especially with the addition of devices like the Petzl ID or the CMC MPD as your first MA change of direction and progress capture device. Plus, this gives you the ability to convert to a lower with friction control already built in. But you can really complicate things by compounding a second MA onto a Z-rig to get a higher ratio MA. You will soon learn that now you have to perform two separate resets of the haul cams. And, if you are out of sequence in the reset, the haul cam of the second MA will jam into the traveling pulley of that system and stop you in your tracks. There are some tricks to really make the resets for this system go nicely, but that will have to wait for another day.

There are hundreds of variations that you can use for compounding MAs, but once again I caution you to remember KISS. I have my favorites and every once in a while the situation calls for something a little different, and that’s where understanding the advantages and disadvantages of the systems is of great value.

For additional video resources on mechanical advantage as well as other techniques and systems, visit Roco Resources.

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