The hazards associated with carbon dioxide in the brewing industry are well known, yet people still die needlessly every year in tragic and completely avoidable accidents in breweries.
Just last year in Germany, which has a good safety record, two workers died in separate incidents at the same brewery. These incidents could have been avoided by following the right carbon dioxide gas safety procedures.
In the first incident, the owner was found dead with his head and torso in a beer mixing tank. It is thought that, after bottling and subsequent cleaning, the owner had leaned in to check the container and was overcome by the carbon dioxide gas.
Then 10 months later, in the same brewery, a worker was found dead in a pressure tank used to recirculate wheat beer. He had probably forgotten to fit a yeast plug and had leaned into the tank—which was already pressurised with carbon dioxide—to fit one. He was found up to his hips in the container and had been poisoned—probably in seconds—due to the high concentration of carbon dioxide.
Both these accidents demonstrate the extremely hazardous nature of carbon dioxide and how quickly one can be overcome by its deadly properties.
Properties & Effects
Carbon dioxide is extremely hazardous and can kill in two ways: either by displacing oxygen, leading to rapid asphyxiation, or as a toxin in its own right.
Exposure to as little as 0.5 percent volume carbon dioxide represents a toxic health hazard, while concentrations greater than 10 percent volume can lead to death. Because carbon dioxide is completely odourless and colourless, there is no physical indication of danger until it is usually too late.
Carbon dioxide is a by-product of the fermentation process and because the gas is heavier than air, it collects at the bottom of containers and confined spaces such as tanks and cellars and can even spill out of fermenting tanks and sink to the brewery floor, where it forms deadly, invisible pockets.
In fact, carbon dioxide is a hazard throughout the brewing process, right through to packaging and bottling.
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Fermentation tanks, beer mixing tanks, silos and other confined spaces in the brewing industry are easily accessible—it is rare for them to be fitted with safety interlocks. For this very reason, rigorous safety systems should be in place and always adhered to.
Employers must assess the risks these areas pose to their employees and endeavour to prevent them. In most cases, both the assessment and the safe working system will require testing of the atmosphere with gas detection equipment.
As a rule, entry should not be routine and should only be carried out if absolutely necessary. However, if entry is necessary—eg: for an inspection or to ensure cleaning has been carried out correctly—suitable safety procedures must be followed.
Firstly, carbon dioxide from the space must be completely removed. This can be done by discharging all the fermentation and pressure gasses directly into the open air using a ring main system. If this is not possible due to the layout, the carbon dioxide must be manually extracted and safely diverted.
Prior to entering a tank or other confined spaces, a ‘release measurement’ of carbon dioxide must be taken using a suitable carbon dioxide monitor. This is the only reliable method to check whether the carbon dioxide concentration is actually at a safe level.
The measurement must be taken by a qualified person, usually by lowering the monitor into the chamber and leaving it there for several minutes. It goes without saying that any monitoring device must be durable, reliable and regularly calibrated and tested.
Anyone entering a tank or other confined spaces must also be equipped with a suitable gas detector. If a certain carbon dioxide concentration is exceeded, the device will go into alarm mode with both audio and visual alarms.
Generally, at a carbon dioxide volume of 0.5 percent by volume, a pre-warning is set off; at one to two percent by volume, the main alarm is activated. With most devices, other alarm thresholds can be selected with the aim of avoiding the alarm sounding too frequently and simultaneously ensuring the safety of the person working in the container.
Both portable and fixed carbon dioxide detectors can be used for carbon dioxide monitoring in breweries. Fixed systems typically comprise one or more detector ‘heads’ connected to a separate control panel.
If a detector reads a dangerous carbon dioxide level, extractor fans are automatically triggered and sirens or visual beacons can also be activated to warn workers to vacate the area. This sort of installation is suited to larger spaces like cellars and plant rooms.
However, much confined space work in the brewing industry take place in more restricted areas like fermentation tanks, where fixed detectors cannot be installed. This means compact portable units are required. Ease of use, with one button operation, should be the norm when it comes to portable detectors. This means minimal training is required while increased safety is ensured.
Combining one or more sensors with powerful audible and visual signals to warn when pre-set gas levels are reached, compact portable detectors are easily carried in a confined space, ensuring that pockets of high carbon dioxide concentration are not missed.
Certain features should be expected in every portable carbon dioxide detector. Clearly, life-saving tools for demanding environments must be as tough as possible, with reliable electronics housed in impact-resistant casings.
While the need to leave gas sensors exposed to the atmosphere means that no instrument can be fully sealed, a high degree of protection against dust and water ingress is essential. Toughness notwithstanding, a well-designed detector will also be light and compact enough to wear for an entire shift.
Finally, because of the difficulties of working in a cramped space, and perhaps under poor lighting, instruments should be easy to use. No matter how advanced a detector’s internal architecture or data management options are, personnel in the field should be faced with nothing more daunting than a clear display, simple one-button operation and loud/bright alarms.
Not taking the risk of carbon dioxide seriously has led to many avoidable deaths. If all the safety procedures described above are observed, the risks of dealing with this colourless, odourless and tasteless gas can be significantly reduced.