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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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Pre-entry Atmospheric Clearance Measurements

Friday, March 17, 2017

The following article was written by Russell Warn and published in ISHN magazine (ishn.com), December 2016. Roco comments have been added to the article and are noted in red.

Working in confined spaces presents a unique and dangerous challenge in combatting the unseen – oxygen deficiency, poisonous or explosive gases, and other hazardous substances are among the most frequent causes of accidents associated with work in confined spaces and containers.

From 2005-2009, the Bureau of Labor Statistics reported nearly two deaths per week, or roughly 96 per year, could be attributed to confined space, with about 61 percent occurring during construction repair or cleaning activities.

With conditions subject to change in a moment’s notice, taking steps to protect against life-threatening dangers should always be a top priority in confined spaces. Performing a thorough clearance measurement is a demanding — yet crucial — task that dictates the safety environment, and should not be taken lightly. To help guide you along your road to enhanced safety, outlined below are several best practices based on frequently asked questions.

When should I perform a clearance measurement?

Conduct clearance measurements immediately before operations begin. Environmental factors such as temperature and air flow can change the atmosphere, causing readings to fluctuate. One shift’s measurement taken at 7 a.m. is not representative of the conditions when work operations commence for another shift at 4 p.m. New clearance measurements must be taken immediately to account for the nine hours of changing temperatures and ventilation patterns, depicting the accurate readings of present conditions.

Roco Comment: In addition to pre-entry clearance measurements, entry into permit spaces during construction activities requires "continuous atmospheric monitoring" unless the entry employer can demonstrate that equipment for continuous monitoring is not commercially available or periodic monitoring is sufficient. Ref. 1926.1203 (e)(2)(vi), 1926.1204 (e)1)(ii), and 1926.1204 (e)(2). Additionally, Roco believes that for "ALL" permit entry operations, it is advisable to provide continuous atmospheric monitoring no matter what the industry activity entails.

What’s the importance of zero-point adjustment?

When performing clearance measurements, it’s crucial to determine the reference point of the gas detector by calibrating the zero-point. The zero-point ensures that the indicated values correspond to the actual existing gas concentrations. In order to determine that the actual zero-point has been found, calibrate equipment in an environment where the hazardous substance is not present, such as fresh air environments. With every scientific test, no matter the field, a control group, which serves as a starting point of reference, permits for the comparison of results to show any contrasting changes. The zero-point calibration acts as such, allowing workers to identify the presence, or lack thereof, of different gas concentrations.

Where do I measure/take the sample?

When it comes to measuring samples, there are four things to keep in mind: the physical properties of gases, and the type and shape, temperature and ventilation patterns of the confined space.

Know the differences between light and heavy gases. Clearance measurement experts must have a strong working knowledge of hazardous substances’ properties, as they play a role in where measurements should be taken. For example, if a sample is pulled from the top of the confined space and hydrogen sulfide (H2S) is detected, the sample may not be entirely reliable. H2S has a molar mass of 34 g/mol, which is significantly heavier than that of air (29 g/mol). As a result, H2S sinks to the bottom of a space, where its concentration would be greatest. Identifying a presence at the top of the confined space says immediate danger and appropriate actions should be taken.

Light gases quickly mix with air and rise to the top. As a result, any measurements in open atmospheres should be performed close to the leak, and increases in concentration should appear in the highest points of the confined space. Heavy gases, on the other hand, should sink and flow like liquids, pass obstacles or stick to them. They barely mix with air like light gases do, so their samples should always be taken at the lowest points of the confined space.

Determine the type/shape of the confined space: In an ideal scenario, each confined space area would be in an “even” or level position. This isn’t always the case, and a container may be placed on an inclined surface, making the highest point in the corner positioned toward the top of the inclined surface. Thus, entry may be nearer to where the heavy gases have accumulated.

Take tabs on temperatures. All matter is made up of atoms and molecules that are constantly moving. When heat is added to a substance, such as a gas, the molecules and atoms vibrate faster. As the gas molecules begin to move faster, the speed of diffusion increases. If the sun has been shining on a tank for hours, there’s a good chance the clearance measurement taken at dawn no longer reflects the current readings due to the increase in diffusion.

Vet the ventilation. Air currents change the position and concentration of air clouds, and often times, the way a confined space is ventilated can affect readings. Containers cannot always be separated from pipelines, or there may be leaks in the tanks that must be accounted.

Roco Comment: Not only is it required by certain OSHA provisions like alternate entry procedures, but Roco highly recommends monitoring the atmosphere prior to initiating ventilation. This is intended to provide a reasonable assessment of the potential atmosphere change should the ventilation equipment fail. The rate for a potential hazard to re-develop will be based on factors such as the effectiveness of isolation, any residual product within the space, temperature, humidity and passive ventilation which are among just some of the factors.

How do I safely conduct the measurement for an accurate reading?

People often question why they can’t just use the carrying strap of their device to lower the device into the confined space for a reading. Although this seems like a simple fix, it’s not a safe or recommended way to conduct the measurement. Lowering the device into the container this way not only obscures the way the display is read, but it may not audibly alarm. If the measured value is slightly below the threshold value and the alarm does not sound, a worker would not be notified of the dangerous concentrations lurking below. Not only this, but measurements may be inaccurate since the measured gases, due to their molar masses, may be concentrated at a higher or lower point within the container. Clearance measurements should be conducted on-site and on-the-ground of the confined space for accurate, safe readings.

Roco Comment: The points made in the preceding paragraph are certainly valid. The best solution that we can offer is to use remote sampling probes or tubes to actively draw (pump) samples from the stratified levels of the space while the direct reading instrument is in a position outside the space to observe the real time readings. To expound upon the point the author makes, if the pre-set threshold for the alarms are not enough to trigger the alarm indicating the presence of a hazardous atmosphere, and the individual performing the assessment relies instead on rapidly pulling the monitor from the space in the hope that they are able to read the display before the values change, is a very dangerous way of approaching this procedure. Depending on the sampling rate of the monitor, the hazardous gas(s) may have cleared from the monitor in the time it takes to withdraw it from the space, and it is very likely that the instrument will display a normal atmosphere by the time it is back within view. Additionally, for areas within the space that cannot be remotely assessed by remote sampling prior to entry, the only safe recourse is to limit entry to the areas that have been assessed and to take a monitor into the space to continuously assess the unreachable regions before venturing further.

What do I need to document during clearance measurement protocols?

Just as it’s important to remain thorough in clearance measurements procedures, it’s equally as important to remain thorough in the general housekeeping protocols surrounding samples. This includes documenting:

  • The container number
  • The measuring point of the container, and whether there was more than one measuring point
  • At which time was the clearance performed
  • Under what condition was the measurement performed
  • Measured hazardous substances
  • Name of person performing measurement
  • Equipment used for clearance

Safety, regardless of job title or responsibility, should be everyone’s top priority. When working in the midst of poisonous and explosive hazards, performing clearance measurements correctly and carefully means not only keeping one’s self safe, but keeping the working environment safe, as well.

About the Author:
Russell Warn is the product support manager for gas detection products at Dräger. He has been in the safety industry for more than 29 years, with most of this time dedicated to gas detection product and application support.

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Q&A: Fall Pro Recert

Wednesday, June 01, 2016

READER QUESTION:
I went through competent person for fall protection several years ago and since that time a lot has changed regarding the types of fall protection equipment and systems that are available. Should I get update training for this role?

ROCO TECH PANEL ANSWER:
Yes, definitely. In fact, ANSI Z359.2 states competent person training update training shall be conducted at least every two years. It is always a great idea for competent persons to stay abreast of not only any legislative changes, but also to stay current on consensus standards such as ANSI, and certainly on emerging equipment technologies. It is amazing how quickly new fall protection equipment is becoming available. It wasn’t long ago that harness mount self-retracting lanyards were just a drawing on an engineer’s desk, and now there are so many different versions it is mind boggling. OSHA’s recognition of suspension trauma as a workplace hazard to fallen suspended authorized persons has created an entire market segment for systems to help deal with this hazard. So receiving update training for this crucial role at least every two years is certainly a great idea.

READER QUESTION:
Can I complete competent person for fall protection training via an on-line course?

ROCO TECH PANEL ANSWER:
We discourage that type of course other than for learning the legislated requirements. There just is no substitute for hands-on training. One of the most important responsibilities of a competent person for fall protection is the performance of periodic equipment inspections. I can’t imagine having any way to show competency of this skill without demonstrating it to a live instructor/evaluator.

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