What causes Hydrocarbon Fires?  

Hydrocarbon fires are caused by fuels containing carbon being burned in oxygen or air. Most fuels contain significant levels of carbon, including paper, petrol, and methane – as examples of solid, liquid or gaseous fuels – hence hydrocarbon fires. 

For there to be an explosion risk there needs to be at least 4.4% methane in air or 1.7% propane, but for solvents as little as 0.8 to 1.0% of the air being displaced can be enough to create a fuel air mix that will explode violently on contact with any spark.

Dangers associated with hydrocarbon fires

Hydrocarbon fires are considered highly dangerous when compared to fires that have ignited as a result of simple combustibles, as these fires have the capacity to burn at a larger scale as well as also having the potential to trigger an explosion if the fluids released cannot be controlled or contained. Therefore, these fires pose a dangerous threat to anyone who works in a high-risk area, the dangers include energy related dangers such as burning, incineration of surrounding objects. This is a danger due to the ability that the fires can grow quickly, and that heat can be conducted, converted and radiated to new sources of fuel causing secondary fires. 

Toxic hazards may be present in combustion products, for example, carbon monoxide (CO), hydrogen cyanide (HCN), hydrochloric acid (HCL), nitrogen dioxide (NO2) and various polycyclic aromatic hydrocarbons (PAH) compounds are dangerous for those working in these environments. CO uses the oxygen that is used to transport the red blood cells around the body, at least temporarily, impairing the body’s ability to transport oxygen from our lungs to the cells that need it. HCN adds to this problem by inhibiting the enzyme that tells the red blood cells to let go of the oxygen they have where it is needed – further inhibiting the body’s ability to get the oxygen to the cells that need it. HCL is a generally an acidic compound that is created through overheated cables. This is harmful to the body if ingested as it affects the lining of the mouth, nose, throat, airways, eyes, and lungs. NO2 is created in high temperature combustion and that can cause damage to the human respiratory tract and increase a person’s vulnerability to and in some cases lead to asthma attacks. PAH’s affects the body over a longer period of time, with serve cases leading to cancers and other illnesses. 

We can look up the relevant health levels accepted as workplace safety limits for healthy workers within Europe and the permissible exposure limits for the United States. This gives us a 15-minute time weighted average concentration and an 8-hour time weighted average concentration. 

For the gases these are: 

Gas  STEL (15-minute TWA)  LTEL (8-hour TWA)  LTEL (8hr TWA) 
CO  100ppm  20ppm  50ppm 
NO2  1ppm  0.5ppm  5 Ceiling Limit 
HCL  1ppm  5ppm  5 Ceiling Limit 
HCN  0.9ppm  4.5ppm  10ppm 

The different concentrations represent the different gas risks, with lower numbers needed for more dangerous situations. Fortunately, the EU has worked it all out for us and turned it into their EH40 standard. 

Ways of protecting ourselves

We can take steps to ensure we do not suffer from exposure to fires or their unwanted combustion products. Firstly of course, we can adhere to all fire safety measures, as is the law. Secondly, we can take a pro-active approach and not let potential fuel sources accumulate. Lastly, we can detect and warn of the presence of combustion products using appropriate gas detection equipment. 

Crowcon product solutions

Crowcon provides a range of equipment capable of detecting fuels and the combustion products described above. Our PID products detect solids and liquid-based fuels once they are airborne, as either hydrocarbons on dust particles or solvent vapours. This equipment includes our GasPro portable. The gases can be detected by our Gasman single gas, T3 multi gas and Gas-Pro multi gas pumped portable products, and our Xgard, Xgard Bright and Xgard IQ fixed products – each of which has the capability of detecting all the gases mentioned. 

Keeping the Emergency Services Safe

Emergency Service Personnel encounter gas related risks as part of their jobs. However, immediate evaluation of their surrounds is key upon arrival as well as continuous monitoring whilst in a rescue situation are vital for the health of all those involved.  

What Gases are Present?

Toxic gases like carbon monoxide (CO) and hydrogen cyanide (HCN) are present if there is a fire. Individually these gases are dangerous and even deadly, the two combined is exponentially worse, known as the toxic twins.  

Carbon monoxide (CO) is a colourless, odourless, tasteless, poisonous gas produced by incomplete burning of carbon-based fuels, including gas, oil, wood, and coal. It is only when fuel does not burn fully that excess CO is produced, which is poisonous. When the excess CO enters the body, it stops the blood from bringing oxygen to cells, tissues, and organs. CO is poisonous as you cannot see it, taste it or smell it but CO can kill quickly without warning.  

Hydrogen Cyanide (HCN) is an important industrial chemical and over a million tonnes are produced globally each year. Hydrogen Cyanide (HCN) is a colourless or light blue liquid or gas that is extremely flammable. It has a faint bitter almond odour, although this isn’t detectable to everyone.  There are many uses for hydrogen cyanide, primarily in the manufacture of paints, plastics, synthetic fibres (for example nylon) and other chemicals. Hydrogen cyanide and other cyanide compounds have also been used as a fumigant to control pests. With other uses being in metal cleaning, gardening, ore-extraction, electroplating, dying, printing and photography. Sodium and potassium cyanide and other cyanide salts may be made from hydrogen cyanide. 

What are the risks?

These gases are dangerous individually. However, exposure to both combined is even more dangerous, so an adequate CO and HCN gas detector is essential where the toxic twins are found. Usually, visible smoke is a good guide, however the Toxic Twins are both colourless.  Combined these gases are usually found in fires. in which, Firefighters and other Emergency Personnel are trained to look out for CO poisoning in fires. However, due to the increased use of plastics and man-made fibres, HCN can be released at up to 200ppm in domestic and industrial fires. These two gases cause thousands of fire related deaths annually, so needs more consideration in fire gas detection.  

The attendance of HCN in the environment may not always lead to exposure. However, for HCN to cause any adverse health effects, you need to come into contact with it, i.e., breathing, eating, drinking, or through skin or eye contact with it. Following exposure to any chemical, the adverse health effects are dependent on a number of factors, such as the amount to which you are exposed (dose), the way you are exposed, the duration of exposure, the form of the chemical and if you were exposed to any other chemicals. As HCN is very toxic, it can prevent the body from using oxygen properly. Early signs of exposure to HCN include headache, sickness, dizziness, confusion and even drowsiness. Substantial exposure may rapidly lead to unconsciousness, fitting, coma and possibly death. If a substantial exposure is survived, there may be long-term effects from damage to the brain and other nervous system damage. Effects from skin contact require a large surface of the skin in order to be exposed. 

What Products are Available?

For Emergency Service Teams, the use of portable gas detectors is essential. Toxic gases are produced when materials are burnt meaning flammable gases and vapours may be present.  

Our 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. In-field pellistor changes for methane, hydrogen, propane, ethane, acetylene (0–100% LEL, with resolution of 1% LEL). By allowing in-field pellistor changes, Gas-Pro detectors give users the flexibility to conveniently test for a range of flammable gases, without needing multiple sensors or detectors. What is more, they can continue to calibrate using existing methane canisters, saving time and money. The gas sensor for hydrogen cyanide has a monitoring measuring range of 0–30 ppm with resolution of 0.1 ppm.  

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) and IR carbon dioxide (for safe area use only). 

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. 

Clip Single Gas Detector (SDG) is an industrial gas detector designed for use in hazardous areas and offers reliable and durable fixed life span monitoring in a compact, lightweight and maintenance-free package. Clip SGD has a 2-year life and is available for hydrogen sulphide (H2S), carbon monoxide (CO) or oxygen (O2). 

Gasman is a full function device in a compact and lightweight package – perfect for customers who need more sensor options, TWA and data capability. It comes available with long-life O2 sensor, MPS sensor technology.

MPS Sensor provides advanced technology that removes the need to calibrate and provides a ‘True LEL’ for reading for fifteen flammable gases but can detect all flammable gases in a multi-species environment. Many industries and applications use or have as a by product multiple gases within the same environment. This can be challenging for traditional sensor technology which can detect only a single gas that they were calibrated for and can result in inaccurate reading and even false alarms which can halt process or production. The challenges faced in multi gas species environments can be frustrating and counterproductive. Our MPS™ sensor can accurately detect multiple gases at once and instantly identify gas type. Our MPS™ sensor has a on board environmental compensation and does not require a correctional factor. Inaccurate readings and false alarms are a thing of the past.

Crowcon Connect is a gas safety and compliance insight solution that utilises a flexible cloud data service offering actionable insight from detector fleet. This cloud-based software provides a top level view of device utilisation with dashboard showing proportion of devices that are Assigned or Unassigned to an operator, for the specific region or area selected. Fleet Insights provides overview of devices switch on/off, synced or in alarm.

TWA Resume – how Crowcon’s patented feature keeps workers safe and makes compliance easier

Most people who work with hazardous gases, and particularly anyone with responsibility for regulatory compliance, will be familiar with the various ways of measuring workplace exposures to gas. You may have heard of short- and long-term exposure limits; these are used to quantify the amount of gas a worker can be exposed to without harm, and most gas detectors track them.

But why differentiate between a short-term and long-term exposure? Well, that has mainly to do with the ways in which gases can be harmful. Some gases (hydrogen cyanide, for example) can be almost immediately fatal if inhaled at a given concentration, but some gases remain harmless if present at or below a much lower level for extended periods of time.

If a worker’s long-term exposure is more than the safe level, however, then some gases can be seriously dangerous to health. And the company in charge may become legally liable because it will have failed to comply with gas regulations.

Non-compliance can get very expensive, very quickly. It is costly in both financial and reputational terms.

Figure 1: This image shows how Crowcon’s proprietary TWA Resume feature keeps workers safe and proves a firm’s compliance, by continuing to monitor exposure to harmful gases even after a mid-shift break or other switch-off during the TWA period. Other detectors don’t do this, they assume any switch-off (e.g. for meals or to drive between sites) signals a new period of measurement, which leaves workers vulnerable to over-exposure and harm, and firms open to legal sanctions due to harm and/or non-compliance. In this image, you can see the workplace exposure limit is breached at around 14:00, but only the Crowcon device with TWA Resume alerts the user to this fact and documents it.

Why use TWAs?

Long-term and short-term workplace exposure limits (WELs) for gases are set out by local regulatory bodies. In the UK, the HSE document EH40 applies. Chronic exposure is often measured via a time-weighted average, or TWA. That means the worker’s exposure to a gas is monitored across a given period, usually 8 hours, to make sure the gas(es) remain(s) at or below the WEL throughout that time.

Unfortunately, it is incredibly easy to mess up a TWA measurement and thus fall foul of the regulations. This is because many standard gas detectors erase the TWA timer history when they are switched off, even if the 8-hour/TWA measurement period is ongoing. So, if an operator turns off one of these detectors because they are having lunch or moving between sites, then switches it back on again when they get back to work (bearing in mind this is a continuation of the TWA period they have already begun to track), the detector will assume that they are beginning a new TWA measurement period.

Clearly, this breaches regulations and can be very dangerous – Figure 1, above, shows why. In this example, the worker exceeds the safe limit at around 14:00 but the traditional device does not ‘see’ this or alert them. The Crowcon device with TWA Resume, however, does sound the alert. And that may save both the worker and the company from a great deal of harm.

What is TWA Resume?

The Crowcon T4 and Gas-Pro ranges have Crowon’s proprietary TWA Resume feature. This  innovative and unique functionality makes sure accurate TWAs are recorded for each and every 8-hour/TWA period, keeping employees safe and removing the risk of non-compliance. Furthermore, it makes it easy for a firm to prove their compliance in the face of any legal claim.

TWA Resume is a patented feature only found on Crowcon devices. When turned off during the TWA measurement period, it stores TWA data in its memory. When a worker switches it back on, they can choose to resume measurement from where it left off, or start a new TWA measurement.

T4 and Gas-Pro detectors store this data in their logs, where is available for further analysis and to prove compliance. Even better, TWA alarms and near-miss data can now be easily exported into Crowcon Connect, a cloud-based portal that gives customers total data visibility. This makes it easy for them to prove compliance, and to be sure that their workers are safe.

Because TWA Resume is a patented Crowcon feature, only Crowcon can provide it. If you want to keep your staff safe while making regulatory compliance much easier, please contact us. We’ll be happy to give you more information on our patented TWA resume feature and discuss how it can help you and your business.