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Safe Confined Space Entry - A Team Approach

Wednesday, September 12, 2018

Having been involved in training for 30 years, I have had the opportunity to observe how various organizations in many different fields approach confined space entry and rescue. And, when it comes to training for Entrants, Attendants and Entry Supervisors, the amount of time and content varies greatly.

Roco Rescue CS EntryMost often, training programs treat the three functions as separate, independent roles locked into a hierarchy based on the amount of information to be provided. However, it’s critical to note, if any one of these individuals fails to perform his or her function safely or appropriately, the entire system can fail – resulting in property damage, serious injury or even death in a confined space emergency.

Before I go any further, I have also seen tremendous programs that foster cooperation between the three functions and use more of a confined space “entry team” approach. This helps to ensure that the entry is performed safely and efficiently.

It also allows all parties to see the overall big picture of a safe entry operation.
In this model, all personnel are trained to the same level with each position understanding the other roles as well. This approach serves as “checks and balances” for confirming that:

• The permit program works and is properly followed;
• The permit is accurate for the entry being performed;
• All parties are familiar with the various actions that need to occur; and,
• The team knows what is expected of each other to ensure a SAFE ENTRY!

However, I am often surprised to find that Entrant and Attendant personnel have little information about the entry and the precautions that have been taken. They are relying solely on the Entry Supervisor (or their foreman) to ensure that all safety procedures are in place. If you have a well-tuned permit system and a knowledgeable Entry Supervisor, this may be acceptable, but is it wise? As the quality of the permit program decreases, or the knowledge and experience of the Entry Supervisor is diminished, so is the level of safety.


Roco CS Entry Supervisor & AttendantIn my opinion, depending exclusively on the Entry Supervisor is faulty on a couple of levels. First of all, the amount of blind trust that is required of that one person. From the viewpoint of an Entrant, do they really have your best interest in mind? And, we all know what happens when we “ass-u-me” anything! Plus, it puts the Entry Supervisor out there on their own with no feedback or support for ensuring that all the bases are covered correctly. There are no checks and balances, and no team approach to ensuring safety.

Looking at how 1910.146 describes the duties of Entrant, Attendant and Entry Supervisor tends to indicate that each role requires a diminishing amount of information. However, we believe these roles are interrelated, and that a team approach is far safer and more effective. To illustrate this, we often pose various questions to Entrants and Attendants out in the field. Here is a sample of some of the feedback we get.

We may ask Entrants…Who is going to rescue you if something goes wrong? Has the LOTO been properly checked? At what point do you make an emergency exit from the space? What are the acceptable entry conditions, and have these conditions been met? How often should the space be monitored? Typically, the answer is, “I guess when the alarm goes off, or when somebody tells me to get out!”

When we talk to Attendants about their duties, we often find they only know to “blow a horn” or “call the supervisor” if something happens, or if the alarm on the air monitor goes off. We also ask…What about when the Attendant has an air monitor with a 30 ft. hose, and there is no pump? Or, if you have three workers in a vertical space and the entire rescue plan consists of one Attendant, a tripod and a winch, plus no one in the space is attached to the cable – what happens then?
  
These are very real scenarios. Scary, but true. It often shows a lack of knowledge and cooperation between the three functions involved in an entry. And, that’s not even considering compliance!
We ask, would it not be better to train your confined space entry team to the Entry Supervisor level? Wouldn’t you, as an Entrant, want to know the appropriate testing, procedures and equipment required for the entry and specified on the permit? Would it not make sense to walk down LOTO with the Attendant and Entrant? This would better train these individuals to understand non-atmospheric hazards and controls; potential changes in atmosphere; or, how to employ better air monitoring techniques. All crucial information.

More in-depth training allows the entry team to take personal responsibility for their individual safety as well as that of their fellow team members. It also provides multiple views of the hazards and controls including how it will affect each team member’s role. Having an extra set of eyes is always a good thing – especially when dealing with the hazards of permit spaces. Let’s face it, we’re human and can miss something. Having a better-trained workforce, who is acting as a team, greatly reduces this possibility.

Roco Rescue Remote MonitoringMany times, we find that the role of Attendant is looked upon as simply a mandated position with few responsibilities. They normally receive the least amount of training and information about the entry. However, the Attendant often serves as the “safety eyes and ears” for the Entry Supervisor, who may have multiple entries occurring at the same time. In reality, the Attendant becomes the “safety monitor” once the Entry Supervisor okays the entry and leaves for other duties. So, there’s no doubt, the better the Attendant understands the hazards, controls, testing and rescue procedures – the safer that entry is going to be!

As previously mentioned, training requirements for Entrant, Attendant and Supervisor are all over the board with little guidance as to how much training or how in-depth that training should be. Common sense tells us that it makes better sense to train entry personnel for their jobs while raising expectations of their knowledge base.

OSHA begins to address some base qualifications in the new Confined Spaces in Construction standard (1926 Subpart AA) by requiring that all confined spaces be identified and evaluated by a “competent person.” It also requires the Entry Supervisor to be a “qualified person.” Does the regulation go far enough? We don’t think so, nor do some of the facilities who require formal, in-depth training courses for their Entrant, Attendant and Entry Supervisor personnel.

OSHA 1926.32 DEFINITIONS:
• Competent person: “One who is capable of identifying existing and predictable hazards in the surroundings or working conditions which are unsanitary, hazardous, or dangerous to employees, and who has the authorization to take prompt corrective measures to eliminate them.” 
• Qualified person: “One who, by possession of a recognized degree, certificate, or professional standing, or who by extensive knowledge, training, and experience, has successfully demonstrated his ability to solve or resolve problems relating to the subject matter, the work, or the project.” 

So, do yourself a favor…go out and interview your Entrants and Attendants on a job.
Find out how much they do (or don’t) understand about the entry and its safety requirements. Do not reprimand them for not knowing, as it may not be their fault. It may be a systemic deficiency and the training mentality of distributing a hierarchy of knowledge based on job assignment.

Simply put, we believe that arming the entry team with additional information results in safer, more effective confined space operations. After all, isn’t that what it’s all about? GO TEAM!

Additional Resources:
• Download our Confined Space Entry Quick Reference Checklist. This checklist reiterates the value of approaching permit-required confined space entries as a team. In addition to OSHA-required duties and responsibilities for the three primary roles, we have included our recommendations as well. These are duties that we feel are important for the individual(s) fulfilling that role to be knowledgeable and prepared to perform if need be.

Safe Entry Workshop: Entrant, Attendant & Entry Supervisor is now available. See the full course description for details.

Roco Rescue - Dennis O'Connell

Author's Bio: Dennis O'Connell has been a technical rescue consultant and professional instructor for Roco Rescue since 1989. He joined the company full-time in 2002 and is now the Director of Training and a Chief Instructor. He currently is responsible for Roco's training curriculum to include Confined Space & High Angle, Trench Rescue, Structural Collapse and Instructor Development. Dennis has played a key role in the development of Roco's Rescue Technician certification programs to NFPA 1006. Prior to joining Roco, he served on the NYPD Emergency Services Unit (ESU) for 17 years. He was a member of NY's Task Force 1 and has responded to numerous national disasters such as the World Trade Center and the Oklahoma City bombing.

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Know When NOT to Enter a Confined Space!

Friday, August 17, 2018

There are countless injuries and deaths across the nation when workers are not taught to recognize the inherent dangers of permit spaces. They are not trained when "not to enter" for their own safety. Many of these tragedies could be averted if workers were taught to recognize the dangers and know when NOT to enter a confined space.

While this incident happened several years ago, it emphasizes the senseless loss of life due to a lack of proper atmospheric monitoring and confined space training. Generally, the focus for training is for those who will be entering spaces to do the work. However, we also must consider those who work around confined spaces – those who may be accidentally exposed to the dangers. Making these individuals aware of the possible hazards as well as to stay clear unless they are properly trained.

Note: This case summary from the New York State Department of Health goes on to say that the DPW had a confined space training program but stopped the training after the last trainer retired.

CASE SUMMARY - TWO (2) FATALITIES
A 48-year-old male worker (Victim I) employed by the Department of Public Works (DPW) and a 51-year-old male volunteer firefighter (FF Victim II) died after entering a sewer manhole located behind the firehouse. In fact, the Fire Chief was on scene because he had been called by the DPW general foreman to unlock the firehouse and move the firetruck so it would not be blocked by the DPW utility truck working at the manhole. Another firefighter also arrived to offer assistance, he later became FF Victim II.

The manhole was 18 feet deep with an opening 24-inches in diameter (see photo above). Worker Victim I started climbing down the metal rungs on the manhole wall wearing a Tyvek suit and work boots in an attempt to clear a sewer blockage. The DPW foreman, another firefighter and FF Victim II walked over to observe. They saw Victim I lying on the manhole floor motionless. They speculated that he had slipped and fallen off the rungs and injured himself. The Fire Chief immediately called for an ambulance.

Meanwhile, FF Victim II entered the manhole to rescue Victim I without wearing respiratory protection. The other firefighter saw that FF Victim II fell off the rungs backwards while he was half way down and informed the Fire Chief. The Fire Chief immediately called for a second ambulance and summoned the FD to respond. FD responders arrived within minutes.

The Assistant Fire Chief (AFC) then donned a self-contained breathing apparatus. He could not go through the manhole opening with the air cylinder on his back. The cylinder was tied to a rope that was held by the assisting firefighters at the ground level. The AFC entered the manhole with the cylinder suspended above his head. He did not wear a lifeline although there was a tripod retrieval system. He secured FF Victim II with a rope that was attached to the tripod.

FF Victim II was successfully lifted out of the manhole. The AFC exited the manhole before a second rescuer entered the manhole and extricated Victim I in the same manner. Both victims were transported to an emergency medical center where they were pronounced dead an hour later. The cause of death for both victims was asphyxia due to low oxygen and exposure to sewer gases.

Contributors to the Firefighter's Death:
• Firefighters were not trained in confined space rescue procedures.
• FD confined space rescue protocol was not followed.
• Standard operating procedures (SOPs) were not established for confined space rescue.

The DPW had developed a permit-required confined space program but stopped implementing it in 2004 when the last trained employee retired. They also had purchased a four-gas (oxygen, hydrogen sulfide, carbon monoxide and combustible gases) monitor and a retrieval tripod to be used during the training. It was reported that a permit-required confined space program was never developed because DPW policy “prohibited workers” from entering a manhole. However, the no-entry policy was not enforced. Numerous incidents of workers entering manholes were confirmed by employee interviews.

This incident could have been much worse. Training is the key, whether it’s just an awareness of the dangers in confined spaces or proper entry and rescue procedures. In this case, the victims had no C/S training even though they may have to respond to an incident, and the worker had not had on-going training through out his career. Periodic training to keep our people safe and aware of proper protocols is key to maintaining a safe work force.

Unfortunately, training is usually one of the first things to be cut when the budget gets tight; however, after an incident, it usually becomes the primary focus. Often the lack of training is determined to be a key element in the tragedy.
Investing in periodic training for the safety of your workforce includes spending the time and money to keep your trainers and training programs up to speed and in compliance. The old saying, “closing the barn doors after the horses escaped,” is no way to protect your people – a little investment in prevention goes along way in preventing these tragedies.

One last comment on my biggest pet peeve – proper, continuous air monitoring. This one step can reduce the potential of a confined space incident by about 50%! Don’t take unnecessary chances that can be deadly.

Dennis O'Connell has been a technical rescue consultant and professional instructor for Roco Rescue since 1989. He joined the company full-time in 2002 and is now the Director of Training and a Chief Instructor. Prior to joining Roco, he served on the NYPD Emergency Services Unit (ESU) for 17 years.

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Do’s & Don’ts for CS Attendants (Hole Watch)

Thursday, October 19, 2017

There continues to be a misconception that a confined space attendant (or “hole watch”) is a menial task to be assigned to the greenest, most inexperienced personnel on the job. That’s a dangerous assumption, and it has been a contributing factor in many confined space fatalities.

In fact, the attendant or hole watch should have a solid understanding of the permit space to be entered. This includes knowing the particulars of any known or potential hazards as well as other pertinent knowledge and skill sets. If you are assigned this crucial role, I hope you understand that the entrant(s) are relying on you. Your performance may have a significant bearing on the outcome, both good and bad.

Do you know everything you need to know in order to perform your duties as a confined space attendant? Don’t assume that you will learn everything you need to know after a two- or three-minute pre-job briefing.

Being an attendant or "hole watch" is a critically important role and failure to properly perform these duties has led to multiple fatalities – both for the entrants and the attendants themselves.

Do understand the known and potential hazards of the confined space. Do take the time to review the SDS (MSDS) for any and all materials or gasses that may be encountered. Do learn what the signs and symptoms of exposure may be. Then, if you detect any of them in the entrant’s behavior or appearance, you can order immediate evacuation.

Don’t gloss over this valuable and readily accessible information only to wonder what caused the entrant(s) to lose consciousness. The SDS (MSDS) provides information on route of exposure; and very importantly, the signs and symptoms of exposure. Don’t miss the opportunity to save the day, and perhaps a life, by learning these early warning signs. This allows evacuation of the space before entrants are no longer able to do so on their own.

Do learn the proper operation of any testing equipment, such as atmospheric monitors. It is also important to understand the limitations of this equipment as well.

Do keep track of all authorized entrants in the space. For entries with multiple entrants, don’t rely on your memory alone. Do use some sort of log or entry roster as a reliable means to accurately identify who is in the space.

Do make sure that you have a reliable means to communicate with the entrants. Do test that means of communication at the very limits of the space to ensure it works. Don’t wait until there is an incident to learn that you cannot alert the entrants, or you cannot hear that their status has changed. If you haven’t heard from the entrants in a while, it can be tempting to go into the space to check on them. This very situation has led to many fatalities in which the attendant was overcome by the same hazard as the authorized entrant(s). At that point, there is no longer anyone available to call for help.

Don’t accept the job assignment until you have been briefed by the entry supervisor on all the planned activities both inside and outside the space. Do remember that oftentimes activities outside the space can create a hazard for the entrants inside the space. Carbon monoxide and spills of hazardous materials are just a couple of examples.

Don’t allow any activities to take place inside or outside the space that are prohibited and are not consistent with the conditions stated on the entry permit, especially if they may create a hazard to the entrants. If those activities were not coordinated and told to you by the entry supervisor, do evacuate the space and call the entry supervisor for guidance.

Don’t leave the space or perform other duties that may interfere with your primary duty of monitoring and protecting the entrants.

Do remain diligent, remember that you are the critical link between the entrants and the rescue service.

Do know how to contact rescue services should they be needed. Don’t wait until it is too late to call for help. Do summons rescue as soon as you determine that the entrants may need assistance escaping from the space. Just remember, you can’t turn back the clock and buy back the time that entrants may have needed to survive. It’s a whole lot easier to turn around the rescue service if it is not needed.

Don’t allow unauthorized persons to approach or enter the permit space. If you are unable to warn them away, do order the evacuation of the authorized entrants. Do immediately inform the entry supervisor of the situation.

Do perform non-entry rescue (retrieval) when needed and if authorized by your employer. Do perform a thorough pre-entry inspection on the retrieval rescue equipment. Do make sure it is appropriate for the type of rescue that may be needed. Do learn and practice the proper operation of the retrieval equipment. Don’t wait until there is an emergency to try and figure it out. Don’t attempt entry rescue unless you are authorized, trained and equipped to do so. Don’t attempt entry rescue until you are relieved by another authorized attendant. Remember, you cannot leave the space unattended!

Don’t take your responsibilities lightly. Do ask the right questions of the entry supervisor and your authorized entrants. Do realize that they are all counting on you. Do ask to be briefed by the entry supervisor regarding any coordination that has been made with other work groups in the area. Do remember that many attendants have perished attempting heroic but ill-advised and unauthorized rescue attempts.

Do remember that your authorized entrants are relying on you. Do take the initiative to learn everything you need to know and how to operate any equipment in support of your entrants. As the hole watch, you are the critical link that can make or break a successful entry operation.

Click picture to download Safety Requirements for Confined Space Attendants.

 Written by Pat Furr, Safety Officer & VPP Coordinator for Roco Rescue, Inc.

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The Clock's Ticking on Timely Response

Tuesday, April 25, 2017

By Dennis O'Connell, Roco Director of Training & Chief Instructor

As Director of Training, I get many questions about rescue techniques and regulations from our students and readers. In the past month alone, I have received three inquiries about "timely response for rescue teams" regarding permit required confined spaces (PRCS). So, let's break it down and try to clear the air on this subject. For clarification, we will refer to the General Industry Standard 1910.146; the Construction Standard 1926-1211; and the Respiratory Standard 1910.134.

In 1910.146, OSHA provides guidance on timely response in Subpart K (Rescue and Emergency Services) and again in Non-Mandatory Appendix F (Rescue Team or Rescue Services Evaluation Criteria). Subpart (k)(1)(i) states: "Evaluate a prospective rescuer's ability to respond to a rescue summons in a timely manner, considering the hazard(s) identified."

This one sentence actually says volumes about response times. The first question to be answered is, "Can the rescue service respond in a timely manner?" It then gives a hint as to what a timely manner should be based on. The second part of the sentence refers to "considering the hazard(s) identified." What this so eloquently says is the response time must be determined based on the possible hazard(s). This means the "known and potential hazard(s)" must be identified for each space to be entered. The hazards discovered -- based on severity, type, how rapidly the hazard could become IDLH or injure the worker, how quickly the need to treat the injury, or how quickly hazards might interfere with the ability to escape the space unaided -- would then be used to determine an acceptable response time. This is why OSHA only alludes to response times and does not set hard and fast times to follow -- it depends on the hazards of that particular space.

Another aspect we need to consider is that "response time" begins when the call for help goes out, not once the team is on scene. It ends when the team is set-up and ready to perform the rescue. So, how long will it take your team to be notified, respond and set-up is a big portion of that acceptable response time calculation. For example, a dedicated onsite fire/rescue team would be able to respond faster than workers who have other responsibilities and need to meet at the firehouse before responding. Or, more quickly than an outside service, such as a municipal department, that would have to respond to the facility, get through the gate, and be led to the scene.

In the note to paragraph (k)(1)(i), it adds: What will be considered timely will vary according to the specific hazards involved in each entry. For example, OSHA 1910.134, Respiratory Protection, requires that employers provide a standby person or persons capable of immediate action to rescue employee(s) wearing respiratory protection while in work areas defined as IDLH atmospheres.

Here we see OSHA better defining an acceptable response time for IDLH atmospheres -- i.e., immediate action! However, it's important to note this doesn't just refer to low O2...depending on the type of contaminant in the atmosphere, other respiratory equipment such as half- or full-face APRs could be used. It may include a dusty environment where the entrant wears a mask and visibility is less than 5 feet. Technically, that would be considered an IDLH environment. Many people get hung up on the use of SAR/SCBA as the trigger for a standby team, and that is just not the case.

For an IDLH atmosphere where respiratory protection is needed, an adequate number of persons (rescuers) is required to perform a rescue from the type of space involved - ready, trained, equipped and standing by at the space -- ready to take immediate action should an emergency occur. So, when dealing with possible IDLH atmospheres, we are looking at "hands-on" the patient in 3-4 minutes as possibly being an appropriate response time. Basically, this is about how long an entrant can survive without air. The only way to safely make rescue entry in that time frame is to have rescuers standing by, suited up and ready to go!

So, if dealing with an IDLH atmosphere, we revert back to 1910.134. Many people think that that is the only time we need a team standing by ready to take immediate action. I pose the question, "If the hazard is a liquid (engulfment hazard), what would be a reasonable response time?" If the victim is Tarzan or Johnny Weissmuller (okay, Michael Phelps, for you younger people), we may have a longer stay-afloat time. But if a non-swimmer, or in an aerated solution or other engulfment hazard, immediate action may be their only chance of survival! And, what about radiation (time, distance, shielding)? I am sure you can think of a few more possibilities.

And, while OSHA referred to an IDLH atmosphere in this example, it's important to consider other IDLH hazards as well. Here's where we note that the definition of IDLH in the Respiratory Standard (1910.134) differs slightly in Permit-Required Confined Spaces (1910.146). The Respiratory standard specifically refers to an IDLH "atmosphere" while the PRCS standard states the following: Immediately dangerous to life or health (IDLH) means any condition that poses an immediate or delayed threat to life or that would cause irreversible adverse health effects or that would interfere with an individual's ability to escape unaided from a permit space. This includes more than simply atmospheric hazards! 

OSHA NOTE: Some materials -- hydrogen fluoride gas and cadmium vapor, for example -- may produce immediate transient effects that, even if severe, may pass without medical attention, but are followed by sudden, possibly fatal collapse 12-72 hours after exposure. The victim feels "normal" until collapse. Such materials in hazardous quantities are considered to be "immediately" dangerous to life or health.

In Non-Mandatory Appendix F (I hate that non-mandatory language), OSHA gives guidance on evaluating response times under Section A - Initial Evaluation. What are the needs of the employer with regard to response time (time for the rescue service to receive notification, arrive at the scene, and set up and be ready for entry)? For example, if entry is to be made into an IDLH atmosphere, or into a space that can quickly develop into an IDLH atmosphere (if ventilation fails or for other reasons), the rescue team or service would need to be standing by at the permit space. On the other hand, if the danger to entrants is restricted to mechanical hazards that would cause injuries (e.g., broken bones, abrasions) a response time of 10 or 15 minutes might be adequate.

Not a bad paragraph for a non-mandatory section of the standard! Here they explain what they are looking for in regards to response times. They even take the OSHA 1910.134 IDLH atmosphere requirement for a team standing by at the space a little further by adding "or into a space that can quickly develop into an IDLH atmosphere." It also states if the hazard is mechanical in nature, 10-15 minutes might be adequate. That’s right, "might" not will be, but might be. Again, it depends on the hazard.

Paragraphs 2-7 in Appendix F goes on to describe other conditions that should be considered when determining response times such as traffic, team location, onsite vs. offsite teams, communications, etc. If you have not done so, I highly recommend that you review the not-so-Non-Mandatory Appendix F. It is also important to note that while it's not mandatory to follow the exact methods described in Appendix F, meeting the requirements are! OSHA also uses the word "should" in Appendix F, not following the OSHA recommendations could certainly lead to some hard questions post incident.

OSHA 1926 Subpart AA Confined Spaces in Construction closely mirrors 1910.146. In this relatively new standard, they simplified the definition of timely response and omitted Non-Mandatory Appendix F, which helps to eliminate the confusion of the "non-mandatory" language, and included the requirements right in the standard, which is good. However, 1910.146 really gives you a better idea of what timely would be for different situations through the notes in Section (k) and Appendix F.

Section 1926.1211 of the Construction Standard for Rescue and Emergency Services (a)(1) states: Evaluate a prospective rescuer’s ability to respond to a rescue summons in a timely manner, considering the hazard(s) identified. This is immediately followed by: Note to paragraph 1926.1211(a)(1). What will be considered timely will vary according to the specific hazards involved in each entry. For example, OSHA1926.103, Respiratory Protection (for construction) requires that employers provide a standby person or persons capable of immediate action to rescue employee(s) wearing respiratory protection while in work areas defined as IDLH atmospheres.

In closing, these regulations are driving you in the same direction for identifying what a timely response would be...THERE IS NO SET TIME FRAME! Each space must be evaluated based on potential hazards and how quickly rescue would need to take place. I hope this will make you take a closer look at "how and what" you consider a timely response. An employer's PRCS program must identify and evaluate the rescue resources to be used. It is then up to the entry supervisor to make sure the identified rescue service is available to respond in a timely manner, which can literally mean life or death for the entrants.

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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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