The Boksburg gas tanker explosion and the transportation of hazardous goods
When a truck carrying highly flammable products like propane, butane, or other liquid petroleum gases is involved in a collision, it can be incredibly dangerous. These types of products are known to be highly explosive, and a collision can easily cause a fire or even an explosion.
Approaching, watching, or filming a truck that has been involved in a collision and is carrying highly flammable products like propane, butane, or other liquid petroleum gases is incredibly dangerous and should be avoided at all costs. The recent incident in Boksburg serves as a powerful reminder of the devastating consequences that can result from not taking these dangers seriously.
If you ever find yourself in such a situation, stay away, call emergency services, and follow their instructions
The pressure wave and heat generated by such an explosion can cause severe burns, injuries, and death to anyone within the vicinity of the explosion. In addition, the chemicals and gases released in a fire or explosion can be harmful to both people and animals and birds and can cause long-term damage to the environment.
In the case, of Boksburg, a truck got stuck under a bridge. After a while a fire developed, which eventually raged out of control and developed into a BLEVE Explosion, killing everyone who was still nearby, watching, or filming the event. At the time when this article was written, the death toll had risen to 40.
A boiling liquid expanding vapour explosion (BLEVE) is a type of explosion that occurs when a pressurized container containing a liquid that is at or above its boiling point is suddenly exposed to a reduction in pressure. This can happen in a variety of situations, such as when a pressurized tank containing a flammable liquid, such as propane or butane, is punctured or otherwise ruptured.
When the container is suddenly exposed to a reduction in pressure, the liquid inside will begin to rapidly boil and expand, creating a large amount of vapour. The increased pressure from the vapour can cause the container to rupture or explode, resulting in a massive release of energy. The rupture of the vessel can cause projectiles, burn, blast waves and toxic gasses, that can cause severe damage to buildings and vehicles in the vicinity, as well as injuries and deaths to people.
BLEVEs are particularly dangerous because they can happen unexpectedly and release a large amount of energy in a short amount of time. The pressure wave and heat generated by the explosion can cause severe burns and injuries and can be fatal to any people who are near the explosion.
Also, if you are in the vicinity of a facility that stores or uses pressurized containers of flammable liquids, it is important to be familiar with emergency evacuation procedures and to be prepared to follow them in the event of an incident. Additionally, if you are in a vehicle, it is best to stay inside the vehicle with windows closed and AC/Heater off until the incident is resolved, or the emergency services have cleared the area.
As an example, Butane and Methane are both hydrocarbons that are made up of hydrogen and carbon. Here are some of the technical properties of butane and methane:
- Molecular formula: C4H10
- Boiling point: -0.5 °C (31.1 °F)
- Melting point: -138.4 °C (-216.1 °F)
- Density (at 20 °C, 1 atm): 2.48 kg/m³
- Specific gravity (at 20 °C): 0.582
- Flashpoint: -11 °C (12.2 °F)
- Autoignition temperature: 446 °C (835 °F)
- Molecular formula: CH4
- Boiling point: -162 °C (-259 °F)
- Melting point: -182.5 °C (-298.5 °F)
- Density (at 0 °C and 1 atm): 0.717 kg/m³
- Specific gravity (at 15.6 °C): 0.554
- Flashpoint: -161 °C ( - 258 °F)
- Autoignition temperature: 537 °C (999 °F)
It is important to note that these properties can vary depending on the specific conditions under which the substances are being measured. Additionally, it is worth mentioning that while both are hydrocarbons, they have different behaviour. For example, Butane is a more volatile substance and is commonly used as a fuel source for lighters, camping stoves, and portable gas heaters. Methane is also used as a fuel source, but it is also a key component of natural gas, which is used as a source of heat and electricity.
The blast radius of a BLEVE is affected by several factors, including the size and pressure of the pressurized container, the properties of the liquid or gas inside the container, and the surrounding environment. One of the most important factors in determining the blast radius of a BLEVE is the amount of product involved in the incident.
To calculate the blast radius of a BLEVE, various models and equations are used, based on the nature of the explosion, the properties of the substance, as well as the geometry of the container. These models can consider factors such as the amount of liquid or gas in the container, the pressure inside the container, the size and shape of the container, and the properties of the liquid or gas.
For example, if we take a hypothetical scenario where the pressurized container is a cylindrical vessel with a volume of 60000 litres and contains propane at 80% of its liquid capacity, the blast radius can be calculated as follows:
- Step 1: Determine the energy of the explosion: The energy of the explosion for propane is about 2.5 KJ/g. So, for 60000 litres of propane, the total energy of the explosion would be 2.5 x (60000 x 0.8) = 900,000 KJ.
- Step 2: Determine the overpressure: The overpressure created by the explosion is the ratio of the maximum pressure to the atmospheric pressure. This can be calculated by using the relation P = E/V where E is the energy of the explosion and V is the volume of the cylindrical container. The overpressure can be estimated to be 15-20 kPa
- Step 3: Determine the blast radius: This can be determined using the following relation R = (P/r)^1/3, where R is the blast radius, P is the overpressure, and r is the density of air (1.225 kg/m³). The blast radius can be estimated to be around 31-35 meters
It is important to note that these calculations are approximate and the actual blast radius may vary depending on the specific conditions of the incident. The above calculation also does not take in the structural and topographical factors of the incident site which can affect the blast radius.
To avoid fatal or serious injury in the event of a BLEVE, it is important to stay as far away as possible from the pressurized container. In general, the Emergency Response Guidebook 2020 recommends an evacuation radius of at least 1,5 km and a preferred evacuation and perhaps as much as 2,2 km away from a BLEVE incident to minimize the risk of injury or death.
From this illustration, and according to the Emergency Response Guidebook, the following can be seen:
- The Blast (Fireball) radius, circled in red, is approximately 77m.
- The EMS distance - the closest that Emergency Services should be from the scene is approximately 306m.
- The minimum evacuation distance, circled in green, is the area that should be evacuated, for safety.
- The ideal area that should be evacuated is about twice that - the area outside the green circle.
- The Thambo Memorial Hospital (Pin 1) is within the EMNS distance, and very close to the blast area.
- The Boksburg Police Station (Pin 2) is only 560m away - well within the minimum evacuation zone.
- The Boksburg Fire Department (Pin 3) is only 790m away - well within the minimum evacuation zone.
- The Ekurhuileni Metro Police Office (Pin 4) is only 970m away - also well within the minimum evacuation zone.
- Even the Ekurhuleni Municipal Buildings (Pin 5) is only 930m away - well within the minimum evacuation zone.
People exposed to a BLEVE explosion at close range -= anyone within the inner red circle - are likely to suffer from a range of injuries depending on their proximity to the explosion, their protective measures, and the nature of the explosion. The following are some of the likely mechanisms of injury and causes of death for people exposed to a BLEVE explosion at close range:
- Burns: The intense heat and flame generated by a BLEVE explosion can cause severe burns to the skin and internal organs. These burns can range from first-degree burns to third-degree burns and can be fatal if they cover a large percentage of the body or involve the face, airway, or vital organs.
- Blast trauma: The pressure wave generated by a BLEVE explosion can cause a range of traumatic injuries, such as blunt trauma, lacerations, fractures, and dislocations. These injuries can occur as a result of being thrown by the blast wave, being struck by debris, or being crushed by collapsing structures.
- Asphyxiation: A BLEVE explosion can release toxic gases, such as carbon monoxide and hydrogen cyanide, which can cause asphyxiation and suffocation. These gases can displace the oxygen in the air, making it difficult for people to breathe, and can cause brain damage or death if exposure is prolonged.
- Projectile injury: The blast can create projectiles like broken pieces of the container, equipment or debris that can fly at high speed and cause serious injuries such as lacerations, fractures, or penetrative injuries.
- Cardiac Arrest: The intense psychological and physical trauma caused by a BLEVE explosion can trigger cardiac arrest in certain individuals.
- Dismemberment: The shockwave of a BLEVE incident is so severe that anyone within the immediate blast radius (less than 77m) might be dismembered. In the Boksburg case, this was graphically illustrated when a hand was found in a nearby tree, days later.
It's crucial to note that these are just some of the possible mechanisms of injury and cause of death and there can be a wide range of injuries depending on the specific circumstances of the BLEVE incident. The best way to avoid these injuries is to stay away from the pressurized containers and not approach or film the scene of an accident involving these containers.
Here are some general guidelines for treating people with serious injuries caused by a BLEVE explosion:
- Call for emergency medical assistance immediately. This is the most important step that should be taken as soon as possible.
- Check for responsiveness and pulse, if the person is not responsive, begin CPR if trained.
- Assess the injuries and provide first aid accordingly. The injuries caused by a BLEVE explosion can range from burns to traumatic injuries, so it is important to evaluate the person's condition and provide appropriate care.
- For traumatic injuries, such as fractures or dislocations, immobilize the affected area to prevent further injury.
- If there is a suspected inhalation injury, quickly move the person to a location with fresh air and monitor their breathing
- Be aware of possible toxic gas or chemical exposure and take appropriate safety measures to protect yourself and the patient.
- If you can smell any chemicals, you are too close to the source and you, and your patients, need to be evacuated as a matter of utmost urgency, even before any fire starts.
It's crucial to note that these are general guidelines, and the treatment will be based on the specific circumstances and conditions of the patient. Also, it's important to remember that first aiders should not exceed their level of training and should always follow the protocols provided by local emergency services.
It's vital to remember that BLEVE explosions are highly dangerous incidents and can cause severe injuries and death. The best way to avoid these injuries is to stay away from the pressurized containers and not approach or film the scene of an accident involving these containers.
When you see a truck accident involving propane or butane gas, it is essential to call 10177, 10111, 084 124, or 112 immediately to alert emergency responders to the situation. When making the call, the dispatchers will need certain information to ensure that the appropriate response is deployed to the scene of the accident. Here is a list of information that will be required by dispatchers when calling 911 in such a situation:
- The location of the accident, including the street address or nearest intersection, as well as any landmarks or landmarks nearby.
- The number of vehicles involved in the accident
- A description of the accident, including the severity of the accident, the extent of damage to the vehicles and any leakage of the propane or butane gas
- Any injuries or fatalities that have occurred as a result of the accident.
- Description of the truck and its cargo, including the type of gas and the size of the container/tanker.
- Any fire or explosion that occurred and the status of the fire.
- Whether or not people have been evacuated from the area, and if not, the number of people in the immediate vicinity.
- Your name and phone number for follow-up questions.
It's important to remain calm and speak clearly when providing this information to the dispatcher and follow their instructions. Providing accurate and timely information can help emergency responders to respond effectively to the accident and minimize the risk of injury or loss of life.
It is also important to not leave the area, of the accident until emergency services arrive and asks you to do so. Whenever any chemicals are involved, stay as far back as possible and don't approach the site, allowing the emergency responders to do their job.
By Stan Bezuidenhout - IBF Investigations, www.ibfusa.info
Stan Bezuidenhout is a highly accomplished and driven forensic specialist, court expert, tactical risk analyst, trainer, speaker, and author. He has dedicated his career to developing a deep understanding and expertise in a wide range of fields related to forensic investigation, risk analysis, and training. He has consistently demonstrated a strong commitment to excellence and a passion for delivering exceptional results in everything he does.
He is a highly qualified and respected professional in the fields of forensic science and risk analysis, with a strong reputation for his expertise and dedication to his work. He is confident in his ability to utilize his skills and knowledge to make a positive impact on any organization or project, and he is always seeking new challenges and opportunities to continue growing and advancing in his career.