Cleanroom Isolators


Hello good people of the world! Today’s post is about cleanroom isolator technology, specifically Restricted Access Barrier Systems (RABS). RABS are typically employed at the high-risk manufacturing step of fill/finish, were finished product may be exposed to the surrounding environment (i.e. the process is “open”). In the case of parenteral (injectable) pharmaceuticals or biologics, where post-fill sterilization is not possible, environmental control at the fill step is of paramount criticality.

Heating, Ventilation, and Air Conditioning (HVAC) general concepts: HVAC is an important system in maintaining cleanroom cleanliness, but is typically categorized as an “indirect-impact” “commission-only” system, separated from the cleanroom itself via High Efficiency Air Particulate (HEPA) filters and controlled via feedback from local cleanroom differential pressure (DP), temperature, and, if required, humidity sensors.  The main components of the HVAC system include the Air Handling Unit, which may be comprised of a mixing chamber (for return and outside air), filters, heaters, coolers, and humidifiers.

Cleanroom general concepts: the cleanroom is typically classified according to ISO 14644-1, GMP EU grades, and/or US Federal Standard 209E classes, among others. A good summary is here. These classifications define the allowable number of total airborne particles and viable airborne particles. Total and viable particulates can be reduced by increasing the air exchange rate, which is the number of times (typically per hour) that the total room air volume moves through the AHU. For class B (ISO 7 in operation), 30-60 air changes are used. For class C (ISO 8 in operation), 20 air changes may be used.  Class A space (ISO 5) could require Unidirectional Air Flow (UDAF), which should be differentiated from Laminar Flow (LF), with an air velocity of 0.45 m/s ± 20%.

In cleanrooms, by far the grossest contributor to airborne particulate counts are the operators. Moving even slightly, an operator might produce more than 2.5 million particles of size 0.3 μm or greater per minute! (source). For this reason alone, barrier technology is critical in Class A cleanroom space. This is typically achieved via an active or passive Restricted Access Barrier System (RABS) or via an Isolator.

A RABS is an area that has a rigid enclosure with safety-interlocked doors, and glove ports for manual interventions. Passive RABS has no aeration equipment. Active RABS has it’s own aeration and filtration equipment.

Isolators are similar to RABS, except that they are hermetically (airtight) sealed to completely separate operators from the process area.

Both the RABS and Isolator create an UDAF over the Class A space.

Which do you use? Which do you prefer? What application would required an Isolator over a RABS?

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