Ventilation When Choosing LAF

Concept Clarification:

• Sterile Cabinets (Class I): These cabinets only provide product protection. They filter room air through a HEPA filter to protect the product.

• Safety Cabinets (Class II): These offer both product and personal protection. They are designed to handle both inflow and outflow of air to maintain safety.

Installation Requirements for Sterile Cabinets 
Sterile cabinets generally do not require extensive installation. These cabinets take room air and filter it through a HEPA filter to achieve the desired product protection. This means that the cabinet does not affect the existing room ventilation, and in fact, it will contribute to an improvement or purification of the overall air quality in the room. When installing a larger number of cabinets in the same room, one should be aware of the potential heat development from these cabinets, as they recirculate room air. It is also important to be aware that some cabinets are equipped with AC motors, which can have higher heat development and greater power consumption. Modern cabinets, on the other hand, are often equipped with EC or DC fans, which use about 60% less energy.

Installation Requirements for Safety Cabinets
In connection with installations in Denmark, one must comply with the local requirements of the Labor Inspection Authority for the laboratory. Most installations will typically require the cabinet to be connected to the ventilation system. Safety cabinets are designed and set to operate with a specific air flow pattern, where the interaction between inflow and outflow of the cabinet must be balanced. This is necessary to ensure that both product and personal protection are intact.

The air exhaust in the table below is for guidance:

Safety cabinets with an EN 12469 certificate will have built-in visual and acoustic alarms for failures in inflow/outflow or downflow. To maintain its flow pattern and prevent unintended alarms, the exhaust amounts will need to be set to the specified amount ± 10%. To accommodate this precise and stable air volume, an installation will typically require the following:

On/Off Damper

An on/off damper connected to the cabinet's control will open the ventilation when the cabinet is in use and close when it is on standby or turned off. This ensures that there is automatic extraction when the cabinet is in use, but also that room air is not drawn through the cabinet when it is turned off or in standby. Since the cabinet removes air from the room, thus affecting the pressure balance in the room, this function will also be used to regulate the supply air to the laboratory, i.e., maintaining the desired pressure in the room whether the cabinet is operational or turned off.

Volume Damper

An on/off damper cannot be adjusted to a precise airflow, so installations with safety cabinets will require a combination with a volume damper. A volume damper keeps the airflow constant at the set amount. In connection with the installation of cabinets, the optimal process will be that the exhaust amount and cabinet testing are performed simultaneously, so this is adjusted in collaboration between the ventilation and LAF technician.

Extended Installation
Test The Ki-Discus test is recommended for new installations of microbiological safety cabinets, as described in BS 5725 – 1992 and the EN 12469 standard.

The Ki-Discus system is designed to ensure either personnel or product protection factor.

This extended safety test takes into account the physical location of the safety cabinet and will respond if the ventilation, inlet fixtures, or anything else disrupts the flow at the working opening of the safety cabinet.

Ki-Discus enables:

Testing without bacterial contamination for the safety cabinet
Testing without bacterial contamination for the laboratory
Results are available immediately after the test is completed.

Safety Cabinets and Height-Adjustable Stands
In Denmark, we primarily use safety cabinets equipped with height-adjustable stands. When installing these, it is important to be aware of the necessary built-in height for the cabinet, including connection to the ventilation system, and the available ceiling height.

A safety cabinet designed for seated work typically has a table height of between 70 and 75 cm. With a height-adjustable stand, the height typically varies between 20 and 30 cm.

The ideal installation, which can facilitate both seated and standing work, should therefore have an adjustable height between 75 and 109 cm. According to the standard EN/ISO 14738, the general built-in height for a safety cabinet, including ventilation connection, should be around 235 cm.

Checklist for Installation of Safety Cabinets:

1. Obtain the exhaust amount and align this with the available ventilation
2. Ensure installation includes an on/off damper and volume damper
3. 230V power supply to the cabinet
4. Possible 230V supply for height-adjustable stand
5. Connection of simultaneous control between cabinet and on/off damper
6. Check ceiling height vs. height of the cabinet, especially for installations with height-adjustable stand
7. Ensure the cabinet has a certificate (EN 12469 or DIN 12980)
8. Installation should be completed with an installation test according to EN 12469.
9. Best if the volume damper adjustment is performed along with this test
10. Possible extended installation test, ki-discus

Safety Cabinets and Energy
Safety cabinets, unlike, for example, fume hoods, always have a fixed window height during operation. This height depends on the brand, but is usually between 170-200 mm. When selecting a cabinet, it should be equipped with EC or DC fans, which consume less energy.

An example:

A 1.2 cabinet with an AC motor consumes about 600 watts per hour
A 1.2 cabinet with an EC motor consumes about 200-300 watts per hour, i.e., a saving of 300-400 watts per hour!!
Most safety cabinets also have a "save function." This can be used when the cabinet is not in use, but there is still a need for protection of product and person. With this function, the flow in the cabinet is reduced, and with some brands, the window height is also limited. This function consumes 40-80 watts.

Certification
A safety cabinet must have at least a certificate, EN12469 or DIN 12980, and possibly additional requirements related to function. However, one should also consider the following in connection with the installation and use of safety cabinets:

• A safety cabinet is only safe when it is correctly installed and subsequently tested
• A safety cabinet is only as safe as the way it is used

It is important to remember that a safety cabinet is only safe when it is correctly installed, tested, and used properly. An LAF License can be an effective tool to ensure correct usage.