Back to School: Back to Basics

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Unlike traditional hoods, which vent the air, toxins and particulate into the external environment, ductless fume hoods use pre-filters, HEPA filters and carbon filters to remove particulate and toxins from the airstream. A ductless fume hood requires no ductwork and may be installed in locations where, barring a significant and expensive renovation process, a traditional fume hood could not. In some instances ductless fume hoods arrive fully assembled, as is the case with all of AirClean Systems workstations. In other instances some manufacturers require that the end user assemble the workstation. It is always advisable to clarify this detail prior to your purchase. Ductless hoods protect the operator and/or the process as well as the environment as the toxins and particulate are captured by the filters versus being released into the environment.

 

See below for a quick education on the filters that make all of this possible:

 

Pre-filters: Pre-filters are electrostatically charged and are the first layer of filtration that the airstream passes through in a ductless workstation. The pre-filters work to capture larger particulate before it passes through to the next layer of filtration. Pre-filters, much like the filters on your furnace, should be replaced every 3 months or when they appear visibly dirty.

 

HEPA filters: HEPA filters capture pathogens and particulate and are 99.997% efficient at 0.3 microns or larger. The clean air that comes through a HEPA filter is considered Class 100/ISO 5 clean air. HEPA filters are typically made of a pleated fibre glass paper. The pleated internal structure of a HEPA filter provides a larger surface area for capturing particulate. Unlike activated carbon filters, there is really only one type of HEPA filter. If your application involved particulate that was smaller than 0.3 microns, than the HEPA filter could easily be replaced by an ULPA filter. ULPA filters are 99.9995% efficient at trapping particles 0.12 microns or larger. HEPA and ULPA filters should be replaced every 12-24 months depending on your usage and application.

 

Carbon filters: Carbon filters adsorb putrid odours, vapours, fumes and gases. The carbon is activated and impregnated in order to increase the filters ability to adsorb and retain specific chemicals. AirClean Systems workstations are equipped with activated bonded carbon filters, which are unique to AirClean Systems products. Loose or granular carbon filters found in other workstations, can be shaken so that all of the carbon ends up on one side of the filter or leaves holes and gaps, through which vapours can easily escape. On the other hand, bonded carbon filters hold the carbon in a predictable matrix and ensure even distribution of the carbon so that no holes or gaps exist. Bonded carbon filters also minimizes carbon dust – which can potentially be more harmful than the application that the filter is adsorbing. Carbon filters should be replaced every 12-24 months depending on your usage and application.

 

Generally speaking:

A ductless workstation that is equipped with pre-filters and activated carbon filters is perfectly suited for those applications that require the protection of the operator from fumes, gases and vapours. The workstation will pull the air away from the operator and up through the filters where the fumes will be adsorbed, and then clean air is re-circulated back into the lab environment.

 

A ductless workstation that is equipped with pre-filters and HEPA filters, and has an updraft airflow is perfectly suited for those applications that require the protection of the operator from hazardous particulate. These workstations will pull the air away from the operator and up through the filters where the particulate is captured. The clean air is then re-circulated back into the lab environment.

 

A ductless workstation that is equipped with pre-filters and HEPA filters, and has a downdraft airflow is perfectly suited to provide non-hazardous applications with a Class 100/ISO 5 clean work environment. With the reverse airflow from the previously mentioned workstations, the air will first be pulled down through the filters at the top of the workstation where the particulate is captured and then clean air is pushed down onto the workspace and out towards the operator.

 

A ductless workstation that is equipped with pre-filters, HEPA filters and activated carbon filters will have an updraft airflow and will be perfectly suited for those applications that require the protection of the operator from both harmful vapours and particulate. These workstations will pull the air away from the operator and push it through a layer of HEPA filters to remove the particulate and then through a layer of activated carbon filters to adsorb the vapours. The clean is then re-circulated back into the lab environment.

 

You should thoroughly discuss your application with the manufacturer/distributor of your ductless workstation to ensure the appropriate filtration system has been determined. With the right selection of filters, you can rest assured that your operator and/or process are protected.

 

AirClean® Systems Canada is your direct source for AirClean® Systems ductless fume hoods, workstations and enclosures. AirClean® Systems products are designed to protect the operator, the process or both from toxic vapours, fumes, gases and particulate. Request your assessment today to get our expert analysis and find out how a ductless systems can benefit your lab today.

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