Percentage of fresh air in recirculating ISO 7 & 8 areas

[Jesus Garicano]

I will like to know if doess it exist a technical or regulatory reason for the injection of 20% of fresh air in recirculating ISO 7 & 8 systems?. Considering the number of recirculations per hour, I do not understand the reason why of this figure. In my opinion recirculating once every two or three minutes, a fresh air injection of 5 to 10% would be enough. It is clear I assume the fact there are no solvents or any other particle producer or chemical in the area which could oblige to implement a total exhaust or any other more restrictive air injectionpolicy, but the operators safety reasons exclusively.

[jyopravel]

I will like to know if doess it exist a technical or regulatory reason for the injection of 20% of fresh air in recirculating ISO 7 & 8 systems?. Considering the number of recirculations per hour, I do not understand the reason why of this figure. In my opinion recirculating once every two or three minutes, a fresh air injection of 5 to 10% would be enough. It is clear I assume the fact there are no solvents or any other particle producer or chemical in the area which could oblige to implement a total exhaust or any other more restrictive air injectionpolicy, but the operators safety reasons exclusively.

Please note the air changes applicable to both the systems i.e. once through and re circulated. The recirculated air also filtered through pre, fine and HEPA filters and the air changes depends on the clean area requirement. The injection percent of fresh air depends up on the area design and occupancy.

Regards

[Jesus Garicano]

Dear Prasad, Thanks for your answer. It is clear it is needed to filter all the air you are handling. My doubts are related to what percentage of fresh air is injected into the system is acceptable. The reason why is because, in my opinion, we are in front of a H&S matter not a GMP related one, and considering in class D (ISO 8) we use an average of 20 recirculations/hour this means we have a full renewal of the air, theoretically, at least every half an hour when the percentage of fresh air injected is 10%. In class C the time for renewal is even sorter. The question is: Is this scope reasonable or is there any regulation that indicates a 20% renewal is the minimum acceptable?
Thanks once more
Jesus Garicano

[jegadeeshkundan]

Dear Prasad, Thanks for your answer. It is clear it is needed to filter all the air you are handling. My doubts are related to what percentage of fresh air is injected into the system is acceptable. The reason why is because, in my opinion, we are in front of a H&S matter not a GMP related one, and considering in class D (ISO 8) we use an average of 20 recirculations/hour this means we have a full renewal of the air, theoretically, at least every half an hour when the percentage of fresh air injected is 10%. In class C the time for renewal is even sorter. The question is: Is this scope reasonable or is there any regulation that indicates a 20% renewal is the minimum acceptable?
Thanks once more
Jesus Garicano

Dear Jesus Garicano,

with respect to H&S we need to maintain minimum oxygen level of 20 in the manufacturing area ( kindly check the oxegen level of manufacturing / processing area)
as u said there is no solvents used in the processing area, kindly let me what are the gases used in the processing area of class c & D(eg Nitrogen etc....)
based on the usage of other gases only we can determine the % of fresh air injection....


Thanks & Regards,
Jagadeesh

[Jesus Garicano]

Dear Jagadeesh,

Apart cell banking room (which is managed with a total exhaust strategy due to the nitrogen presence), and the upstream suite (small amounts of CO2 injected in bioreactors) there are no other inert or dangerous gases or vapours in the suites. So the only concern is the oxygen requirement, and CO2 inyected in the system by the operators breathing. Considering there are a couple or maximum 3 operators in a suite of 40 m3 of volume and a recirculation rate of 30 room vol/hour I think a percentage of 5% of fresh air inyected in each recirculation is more than enough to maintain a safe oxygen percentage. Is it correct this hypothesis?

Thanks a lot an kind regards,

Jesus

Dear Jesus Garicano,

with respect to H&S we need to maintain minimum oxygen level of 20 in the manufacturing area ( kindly check the oxegen level of manufacturing / processing area)
as u said there is no solvents used in the processing area, kindly let me what are the gases used in the processing area of class c & D(eg Nitrogen etc....)
based on the usage of other gases only we can determine the % of fresh air injection....


Thanks & Regards,
Jagadeesh