oRABS air intake issue
During a recent visit to a sterile fill-finish facility in its finalization phase, I anticipated encountering a state-of-the-art establishment. However, to my surprise, I observed a filling line enclosed in an active open Restricted Access Barrier System (oRABS), where the air intake for the RABS was positioned near the ceiling, as demonstrated in Picture 1:
The oRABS system experiences significant air demand due to its entire ceiling being equipped with HEPA filters operating at an airspeed of 0.45m/sec. Each square meter of such a filter requires an intake of 1,620 m3/hr. It's evident that the oRABS system has a substantial impact on the airflow within the filling room.
Picture 2 illustrates a feasible installation of the oRABS system in a Grade B cleanroom, highlighting its influence on airflows.
The diagram serves as an example but effectively illustrates the impact of air intakes positioned near the ceiling. This configuration leads to two primary consequences:
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1. Air escaping from the oRABS vents is drawn upwards, resulting in airflow moving in the incorrect direction (12,200m3/hr in the example shown in picture 2)
2. Air supplied by the room inlets, whether through direct HEPA filters or swirl diffusers, is drawn towards the oRABS intakes rather than effectively washing the room and removing contaminants. (4,000m3/hr out of the total 10,800m3/hr are not active in cleaning the room as shown in the example presented in picture 2))
Despite these issues, oRABS vendors continue to manufacture such systems due to their simplicity and cost-effectiveness. However, the preferred solution involves providing the necessary air from the technical area above the room. Various options exist for achieving this, such as utilizing return air ducts, supplying air from an air handling unit (AHU), or using a plenum, as depicted in Picture 3 below.
Implementing these alternatives can effectively eliminate the aforementioned problems.
Vice President & Head-Drug Product Manufacturing @ Biological E. |Vaccine Division I Strategic Leader |Transforming - People, Process, & Technology |Regulatory - FDA Compliance |Digitization & Automation
11 个月Thanks for sharing
CEO / Executive Consultant
11 个月This antiquated design should have been vanished, but to my big (negative) surprise, it's still offered (this year). Questioning why this supplier is still offering this: "industry is asking for it". Other response: "APS still passing".., meaning "Barr" is insufficiently echoing through the industry [paraphrasing]: you cannot test quality into your facility. While Annex 1 (TRS1044-Annex2) is quite clear -I thought- §9.32 "....The APS should not be considered as the primary means to validate the aseptic process or aspects of the aseptic process....". I am still confronted with these type of designs, luckily inspectors are now issuing serious observations against this design. Seems to be the only way to get attention.... Why is this so difficult, since there is not a big difference in overall capital investment between one or the other design...
Executive Director @ Energy & Carbon Reduction | Chartered Engineer
11 个月Simple - don’t fight gravity and let the large MCP settle with the help of flushing downward airflow.
Richter Gedeon
11 个月Arnan, it is just great to highlight on the rarlly poor and old fashioned design (even in case of simple LAF units) from engineering point of view, and on top of this, just consider from the contamination control angle: imagine as the air flows out from the lower part of the Grade A oRABS into Grade B, touching the room floor before it goes up again to the cealing level located air intake, so whirs up the floor dirt and it starts going up, while contaminating the operator standing near the oRABS. See it by the mean of a smoke study.
Business Owner of "10AR - Sterile Engineering Solutions"
11 个月The influence of high oRABS intake significantly affects the Grade B environment as outlined in the aforementioned points. A poorly designed Grade B environment poses a critical challenge that cannot be easily mitigated or overlooked through risk assessment alone. The repercussions of suboptimal design may extend beyond immediate concerns, potentially impacting unanticipated areas within the facility. Therefore, prioritizing robust design principles and solutions is imperative to maintain the integrity and effectiveness of Grade B environments.