What are the Dangers of Confined Space Entry?

What is Confined Space and is it Classified?

Confined Space is a global concern. In this blog we are referencing the UK’s Health and Safety Executive’s dedicated documentation, as well as the United States OSHA ones, as these are broadly familiar to other countries own health and safety procedures. 

A Confined Space is a location that is substantially enclosed although not always entirely, and where serious injury can occur from hazardous substances or conditions within the space or nearby such as a lack of oxygen. As they are so dangerous, it has to be noted that any entry to confined spaces must be the only and final option in order to carry out work. Confined Spaces Regulations 1997. Approved Code of Practice, Regulations and guidance is for employees that work in Confined Spaces, those who employ or train such people and those who represent them. 

The Risks and Hazards:VOCs

A Confined Space that contains certain hazardous conditions may be considered a permit-required confined space under the standard. Permit-required confined spaces can be immediately dangerous to operator’s lives if they are not properly identified, evaluated, tested and controlled. Permit-required confined space can a defined as a confined space where there is a risk of one (or more) of the following: 

  • Serious injury due to fire or explosion 
  • Loss of consciousness arising from increased body temperature  
  • Loss of consciousness or asphyxiation arising from gas, fume, vapour, or lack of oxygen  
  • Drowning from an increase in the level of a liquid  
  • Asphyxiation arising from a free-flowing solid or being unable to reach a respirable environment due to being trapped by such a free-flowing solid 

These arise from the following hazards: 

  • Flammable substances and oxygen enrichment (read more) 
  • Excessive heat 
  • Toxic gas, fume or vapours 
  • Oxygen deficiency 
  • Ingress or pressure of liquids 
  • Free-flowing solid materials 
  • Other hazards (such as exposure to electricity, loud noise or loss of structural integrity of the space) vocs

Confined Space Identification

HSE classify Confined Spaces as any place, including any chamber, tank, vat, silo, pit, trench, pipe, sewer, flue, well or other similar space in which, by virtue of its enclosed nature, there arises a reasonably foreseeable specified risk, as outlined above.  

Most Confined Spaces are easy to identify although, identification is sometimes required as a Confined Space is not necessarily be an enclosed on all sides – some, such as vats, silos and ships’ hold, may have open tops or sides. Nor are exclusive to a small and/or difficult to work in space – some, like grain silos and ships’ holds, can be very large. They may not be that difficult to get in or out of – some have several entrances/exits, others have quite large openings or are apparently easy to escape from. Or a place where people do not regularly work – some Confined Spaces (such as those used for spray painting in car repair centres) are used regularly by people in the course of their work 

There may be instances where a space itself may not be defined as a Confined Space, however, while work is ongoing, and until the level of oxygen recovers (or the contaminants have dispersed by ventilating the area), it is classified as a Confined Space. Example scenarios are: welding that would consume some of the available breathable oxygen, a spray booth during paint spraying; using chemicals for cleaning purposes which can add volatile organic compounds (VOCs) or acidic gases, or an area subjected to significant rust which has reduced available oxygen to dangerous levels. 

What are the Rules and Regulations for Employers?

OSHA (Occupational Safety and Health Administration) have released a factsheet that highlights all the rules and regulations of residential workers in Confined Spaces.  

Under the new standards, the obligation of the employer will depend on what type of employer they are. The controlling contractor is the main point of contact for any information about PRCS on site.  

The Host employer: The employer who owns or manages the property where the construction work is taking place. 

Employer can’t rely solely on the emergency services for rescue. A dedicated service must be ready to act in the event of an emergency.  The arrangements for emergency rescue, required under regulation 5 of the Confined Spaces Regulations, must be suitable and sufficient. If necessary, equipment to enable resuscitation procedures to be carried out should be provided. The arrangements should be in place before any person enters or works in a confined space. 

The Controlling contractor: The employer who has overall responsibility for construction at the worksite. 

 The Entry employer or Sub Contractor: Any employer who decides that an employee it directs will enter a permit-required confined space. 

Employees have the responsibility to raise concern such as helping highlight any potential workplace risks, ensuring that health and safety controls are practical and increasing the level of commitment to working in a safe and healthy way.  

Testing/ Monitoring the Atmosphere:

Prior to entry, the atmosphere within a confined space should be tested to check the oxygen concentration and for the presence of hazardous gas, fume or vapour. Testing should be carried out where knowledge of the confined space (e.g. from information about its previous contents or chemicals used in a previous activity in the space) indicates that the atmosphere might be contaminated or to any extent unsafe to breathe, or where any doubt exists as to the condition of the atmosphere. Testing should also be carried out if the atmosphere is has been previously contaminated and was ventilated as a consequence (HSE Safe Work in Confined Spaces: Confined Spaces Regulations 1997 and Approved Codes of Practice). 

The choice of monitoring and detecting equipment will depend on the circumstances and knowledge of possible contaminants and you may need to take advice from a competent person when deciding on the type that best suits the situation – Crowcon can help with this.  

Monitoring equipment should be in good working order. Testing and calibration may be included in daily operator checks (a response check) where identified as necessary in accordance with our specification.  

Where there is a potential risk of flammable or explosive atmospheres, equipment specifically designed to measure for these will be required and certified Intrinsically Safe. All such monitoring equipment should be specifically suited for use in potentially flammable or explosive atmospheres. Flammable gas monitors must be calibrated for the different gases or vapours which the risk assessment has identified could be present and these may need alternative calibrations for different confined spaces. Get in touch if you require any help 

Testing should be carried out by people who are competent in the practice and aware of the existing standards for the relevant airborne contaminates being measured and are also instructed and trained in the risks involved in carrying out such testing in a confined space. Those carrying out the testing should also be capable of interpreting the results and taking any necessary action. Records should be kept of the results and findings ensuring that readings are taken in the following order: oxygen, flammable and then toxics. 

The atmosphere in a confined space can often be tested from the outside, without the need for entry, by drawing samples through a long probe. Where flexible sample tubing is used, ensure that it does not draw water or is not impeded by kinks, blockages, or blocked or restricted nozzles, in-line filters can help with this. 

What products are Intrinsically Safe and are suitable for Confined Space Safety?

These products are Certified to meet local Intrinsically Safe Standards.  

The Gas-Pro portable multi gas detector offers detection of up to 5 gases in a compact and rugged solution. It has an easy-to-read top mount display making it easy to use and optimal for confined space gas detection. An optional internal pump, activated with the flow plate, takes the pain out of pre-entry testing, and allows Gas-Pro to be worn either in pumped or diffusion modes. 

Gas-Pro TK offers the same gas safety benefits as the regular Gas-Pro, while offering Tank Check mode which can auto-range between %LEL and %Volume for inerting applications. 

T4 portable 4-in-1 gas detector provides effective protection against 4 common gas hazards: carbon monoxide, hydrogen sulphide, flammable gases, and oxygen depletion. The T4 multi gas detector now comes with improved detection of pentane, hexane, and other long chain hydrocarbons. 

Tetra 3 portable multi gas monitor can detect and monitor the four most common gases (carbon monoxide, methane, oxygen, and hydrogen sulphide), but also an expanded range: ammonia, ozone, sulphur dioxide, H2 filtered CO (for steel plants). 

What’s so Important about my Monitors Measuring Range?

What is a Monitor Measuring Range?

Gas monitoring is usually measured in PPM range (parts per million), percentage volume or percentage of LEL (lower explosive limit) this enables Safety Managers, to ensure that their operators are not being exposed to any potentially harmful levels of gases or chemicals. Gas monitoring can be done remotely to ensure that the area is clean before a worker enters the area as well as monitoring gas through a permanently fixed device or body worn portable device to detect any potentially leaks or hazardous areas during the course of the working shift.  

Why are Gas Monitors essential and what are the Ranges of deficiencies or enrichments?

There are three main reasons why monitors are needed; it is essential to detect oxygen deficiencies or enrichment as too little oxygen can prevent the human body from functioning leading to the worker losing consciousness. Unless the oxygen level can be restored to a normal level the worker is at risk of potential death. An atmosphere is considered to be deficient when the concentration of O2 is less than 19.5%. Consequently, an environment that has too much oxygen in it is equally dangerous as this constitutes a greatly increased risk of fire and explosion, this is considered when the concentration level of O2 is over 23.5%. 

Monitors are required when Toxic Gases are present of which can cause considerable harm to the human body. Hydrogen Sulphide (H2S) is a classic example of this. H2S is given off by bacteria when it breaks down organic matter, due to this gas being heavier than air, it can displace air leading to potential harm to persons present and is also a broad-spectrum toxic poison.  

Additionally, gas monitors have the ability to detect flammable gases. Dangers that can be prevented through using a gas monitor are not only though inhaling but they are a potential hazard due to combustion. gas monitors with an LEL range sensor detects and alert against flammable gases.  

Why are they important and how do they work?

Measurement or Measuring Range is the total range that the device can measure in normal conditions. The term normal meaning no overpressure limits (OPL) and within maximum working pressure (MWP).  These values are usually found on the product website or specification datasheet. The measuring range can also be calculated by identifying the difference between the Upper Range Limit (URL) and the Lower Range Limit (LRL) of the device. When trying to determine the range of the detector it is not identifying the area of square footage or within a fixed radius of the detector but instead is identifying the yielding or diffusion of the area being monitored. The process happens as the sensors respond to the gases that penetrate through the monitor’s membranes. Therefore, the devices have the ability to detect gas that is in immediate contact with the monitor. This  highlights the significance of understanding the measuring range of gas detectors and highlight their importance for the safety of the workers present in these environments.   

Are there any products that are available?

Crowcon offer a range of portable monitors; The Gas-Pro portable multi gas detector offers detection of up to 5 gases in a compact and rugged solution. It has an easy-to-read top mount display making it easy to use and optimal for confined space gas detection. An optional internal pump, activated with the flow plate, takes the pain out of pre-entry testing and allows Gas-Pro to be worn either in pumped or diffusion modes. 

The T4 portable 4-in-1 gas detector provides effective protection against 4 common gas hazards: carbon monoxide, hydrogen sulphide, flammable gases and oxygen depletion. The T4 multi gas detector now comes with improved detection of pentane, hexane and other long chain hydrocarbons. Offering you compliance, robustness and low cost of ownership in a simple to use solution. T4 contains a wide range of powerful features to make everyday use easier and safer. 

The Gasman portable single gas detector is compact and lightweight yet is fully ruggedised for the toughest of industrial environments. Featuring simple single button operation, it has a large easy-to-read display of gas concentration, and audible, visual and vibrating alarms.  

Crowcon also offer a flexible range of fixed gas detection products that can detect flammable, toxic and oxygen gases, report their presence and activate alarms or associated equipment. We use a variety of measurement, protection and communications technologies and our fixed detectors have been proven in many arduous environments, including oil and gas exploration, water treatment, chemical plants and steel mills. These fixed gas detectors are used in many applications where reliability, dependability and lack of false alarms are instrumental to efficient and effective gas detection. These include within the automotive and aerospace manufacturing sectors, on scientific and research facilities and in high-utilisation medical, civil or commercial plants. 

Explosion hazards in inerted tanks and how to avoid them

Hydrogen sulphide (H2S) is known for being extremely toxic, as well as highly corrosive. In an inerted tank environment, it poses an additional and serious hazard combustion which, it is suspected, has been the cause of serious explosions in the past.

Hydrogen sulphide can be present in %vol levels in “sour” oil or gas. Fuel can also be turned ‘sour’ by the action of sulphate-reducing bacteria found in sea water, often present in cargo holds of tankers. It is therefore important to continue to monitor the level of H2S, as it can change, particularly at sea. This H2S can increase the likelihood of a fire if the situation is not properly managed.

Tanks are generally lined with iron (sometimes zinc-coated). Iron rusts, creating iron oxide (FeO). In an inerted headspace of a tank, iron oxide can react with H2S to form iron sulphide (FeS). Iron sulphide is a pyrophore; which means that it can spontaneously ignite in the presence of oxygen

Excluding the elements of fire

A tank full of oil or gas is an obvious fire hazard under the right circumstances. The three elements of fire are fuel, oxygen and an ignition source. Without these three things, a fire can’t start. Air is around 21% oxygen. Therefore, a common means to control the risk of a fire in a tank is to remove as much air as possible by flushing the air out of the tank with an inert gas, such as nitrogen or carbon dioxide. During tank unloading, care is taken that fuel is replaced with inert gas rather than air. This removes the oxygen and prevents fire starting.

By definition, there is not enough oxygen in an inerted environment for a fire to start. But at some point, air will have to be let into the tank – for maintenance staff to safety enter, for example. There is now the chance for the three elements of fire coming together. How is it to be controlled?

  • Oxygen has to be allowed in
  • There may be present FeS, which the oxygen will cause to spark
  • The element that can be controlled is fuel.

If all the fuel has been removed and the combination of air and FeS causes a spark, it can’t do any harm.

Monitoring the elements

From the above, it is obvious how important it is to keep track of all the elements that could cause a fire in these fuel tanks. Oxygen and fuel can be directly monitored using an appropriate gas detector, like Gas-Pro TK. Designed for these specialist environments, Gas-Pro TK automatically copes with measuring a tank full of gas (measured in %vol) and a tank nearly empty of gas (measured in %LEL). Gas-Pro TK can tell you when oxygen levels are low enough to be safe to load fuel or high enough for staff to safely enter the tank. Another important use for Gas-Pro TK is to monitor for H2S, to allow you judge the likely presence of the pryophore, iron sulphide.

Hazards of Ammonia – it’s chilling!

With the reduction in use of chlorofluorocarbon (CFC) and hydrochlorofluorocarbon (HCFC) gases in refrigeration and air conditioning systems has come an increase in the use of ammonia. Use of ammonia avoids the strong green house effect for which use of CFCs and HCFCs was banned, but it brings issues of it own. Much of the food we eat will have spent some time in storage chilled using ammonia. Continue reading “Hazards of Ammonia – it’s chilling!”

The don’ts and don’ts of zeroing your CO2 detector

Unlike other toxic gases, carbon dioxide (CO2) is all around us, albeit at levels too low to cause health issues under normal circumstances. It raises the question, how do you zero a CO2 gas detector in an atmosphere where CO2 is present?

Continue reading “The don’ts and don’ts of zeroing your CO2 detector”

Hydrogen Sulphide Hazards

Next in our series of short videos is our hydrogen sulphide detection factoid.

Where is H2S found?

Hydrogen sulphide is a significant danger to workers in many industries. It is a by-product of industrial processes, such as petroleum refining, mining, paper mills, and iron smelting. It is also a common product of the biodegradation of organic matter; pockets of H2S can collect in rotting vegetation, or sewage itself, and be released when disturbed.

Continue reading “Hydrogen Sulphide Hazards”

Carbon Dioxide – Friend and Foe?

Carbon dioxide (CO2) gas is commonly used in the manufacture of popular beverages. The leak at the Greene King brewery in Bury St Edmunds (UK) last week, is a reminder of the importance of effective gas detection. It resulted in twenty workers having to be rescued by emergency services and local residents being evacuated. So what is carbon dioxide, why is it dangerous and why do we have to monitor it carefully?

Continue reading “Carbon Dioxide – Friend and Foe?”

Detecting VOCs with PID – how it works

Having recently shared our video on pellistors and how they work, we thought it would make sense to also post our video about PID (photo-ionisation detection). This is the technology of choice for monitoring exposure to toxic levels of another group of important gases – volatile organic compounds (VOCs).

Continue reading “Detecting VOCs with PID – how it works”

Onshore oil not new, but is it the future?

The onshore oil industry is often overlooked and the latest news that there could be up to 100 billion barrels of oil beneath the South of England has surprised many. However, on-shore production is more prevalent worldwide than people realise.

Continue reading “Onshore oil not new, but is it the future?”