Importance of Technical Ventilation of EN-Type Fire Resistant Cabinets
Working with hazardous substances is part of day-to-day business for many companies, as chemicals, flammable liquids and the like are essential for a wide variety of activities. The use of these substances in the workplace requires legally compliant storage, e.g. in Type 90 safety storage cabinets. In order to ensure safe working conditions, explosion protection and compliance with occupational safety limits, recirculating air filter units for the technical ventilation of these safety storage cabinets have proven their worth wherever a connection to a fixed exhaust air system to the outside cannot be realized.
Companies must ensure that their employees are protected when working with hazardous substances through safe handling and legally compliant storage of these substances. A key element to ensure safe storage are safety cabinets with 90-minute fire protection as a decentralized storage solution directly at the workplace. Proper storage of hazardous substances also means preventing the formation of dangerous vapors and ensuring explosion protection. How can this be achieved?
Why Does Technical Ventilation Matter?
If stored containers are not or no longer correctly sealed (no longer sealed by the manufacturer) or if leaks occur and liquid hazardous substances can therefore evaporate, hazardous vapors can accumulate in the safety storage cabinet. In the correct mixing ratio with the oxygen contained in the air, an explosive atmosphere can then form. To prevent this, technical ventilation of safety storage cabinets is common practice. This can be achieved by connecting to a fixed exhaust air system to the outside. For safe capture of the vapors and gases at the point where they are released or produced, a plug-in extraction air unit can also be placed on the cabinet to support the exhaust air system. Plug-in extraction air units are particularly easy to install, quiet and ideal for use directly in the working environment. However, technical ventilation can also be achieved using recirculating air filter units. The latter are always an optimal solution when complex wall openings and exhaust air systems are not an option for ventilating safety storage cabinets because they are too costly or structurally impossible to implement.
The 3 Pillars of Technical Ventilation
Technical ventilation with recirculating air filter units offers three key advantages - similar to an exhaust air solution to the outside: Explosion protection, compliance with occupational health limits and product longevity.
Explosion protection:
For each flammable hazardous substance, its safety data sheet specifies a lower explosion limit (LEL). This is the threshold below which a mixture of flammable vapors and oxygen is not explosive (= lean mixture). The LEL should not be exceeded. To ensure this, it is important to vent safety cabinets according to the air exchange rates defined for hazardous materials. For flammable liquids, for example, a 10-fold air exchange rate per hour in the cabinet applies.
Compliance with occupational health limits:
Vapors of hazardous substances can lead to acute and chronic damage to health. Technical ventilation systems can minimize this risk. This ensures not only the immediate safety but also the long-term well-being of employees.
Product longevity:
Technical ventilation is also crucial for the longevity of the safety storage cabinets themselves, as the lack of ventilation can lead to corrosion over time under certain circumstances. This means that even the highest quality cabinets can wear out prematurely. Technical ventilation ensures the longevity of the safety storage cabinets thanks to the removal of vapors.
An All-round Convincing Solution
All this is guaranteed by plug-in recirculating air filter units (UFA) – and are therefore an important addition to the cabinets themselves. The plug-in recirculating air filter units are capable of permanently retaining more than 99.999 % of solvent vapors (hydrocarbons) up to filter saturation. On top of this, they score points for flexibility, cost savings and efficiency. They can be fitted to the safety storage cabinet in just a few simple steps and connected to the exhaust air connection of the cabinet. Once connected to the power supply, they start working immediately.
Technical Ventilation With Filtration: How the Recirculating Air Filter Unit Works
The technical ventilation of safety storage cabinets is subject to requirements in terms of functionality and minimum air exchange rates. Normally, the exhaust air connection is located at the top of the cabinet whereas the actual exhaust air extraction is effective at the bottom. This design is based on the principle that vapors from flammable hazardous substances, which are denser than air, settle at the bottom of the cabinet. From there, they are then extracted by the UFA and extracted into the filter unit.
The Optimum Air Exchange Rate: Safe and Efficient
In order to effectively remove hazardous vapors, a 10-fold air exchange rate per hour in the cabinet is prescribed for flammable liquids (other values apply for gases, acids and alkalis). This ventilation rate is also guaranteed by the recirculating air filter unit and all other options. This means that the entire air inside the cabinet is completely exchanged at least 10 times per hour, as the UFA draws contaminated air out of the cabinet via the exhaust air connection and then returns it to the work area after cleansing. The resulting negative pressure in the cabinet is balanced out by an air supply connection, through which fresh air flows from the work area into the cabinet interior. The advantage of a recirculating air filter unit compared to an exhaust air system is that no heated or treated room air is led to the outside, but is returned to the work area. This prevents energy losses.
Also, ventilation with higher air exchange rates does not significantly increase safety, but does lead to disproportionately higher energy consumption and higher operating costs. The recommended rate of 10 air changes per hour for the storage of flammable liquids therefore offers the optimum combination of safety and economy.
Activated Carbon Filter: Sustainable Recirculating Air Filtration
High-performance activated carbon filters are installed in the recirculating air filter unit, which effectively retain hazardous vapors such as hydrocarbons and thus ensure the safety of the environment. The use of these activated carbon filter cassettes is sustainable: When the absorption capacity of the activated carbon has reached its limits, the filter needs to be replaced. The filter can be replaced either directly by the manufacturer or by yourself using the instructions. If the manufacturer replaces the filter, part of the activated carbon can be recycled free of charge. The cover of the filter, i.e. the cassette, is made of corrosion-resistant, robust plastic and can also be reused.
A Reliable System
Thanks to permanent measurement, the UFA independently monitors filter saturation and exhaust air volume. A color display on the device shows the operating status and reports even the smallest exceedance of the specified limit values. In the event of a filter breakthrough – a filter breakthrough means that the pores of the filter are completely saturated and can therefore no longer absorb pollutants and may even release them again as a result – the ventilation switches off automatically. Using a potential-free alarm contact, the UFA can also send a message to a central control station in the event of a problem. The effectiveness of the UFA system has been tested by an independent testing institute.
