contamination in class 100 000 cleanroom and gowning 1

[davro]

I am investigating a contamination problem with a class 100000 clean room for a Medical devices plant.I would like to know what is the recommended air change per hour for a class 100 000 cleanroom and its gowning area and where would i find the information to back this up.Also as there is increased traffic in the cleanrooms is there any way to counteract the associated increase in contamination.
I would greatly appreciate any help from any of you out there.Thanks in advance!

 

[quark]

There are no rules or guidelines, unfortunately, on this issue. The designer should depend upon his and others experience in this case. My experience in Oral Solid Dosage facilities comfort me anything between 20 to 30 ACPH for a class 100000 area. If the gowning area is at less pressure to main area, then 20 to 30 ACPH is enough or else, you have to go for a bigger number.

Whyte's book on cleanroom technology can be a good reference if you want these figures in black and white (for a cover up.

There are some smart(!?)garment manufacturers out there, who make garments with a claimed filtration level (I saw a numeric as high as 99.7%). May be, you can try out.

 

[davro]

Quark thanks for the responce, on investigating i found that the air changes in certain areas are as low as 10 to 15 ac/h also with an increase in traffic plant wide there is now 3 no. cleanrooms failing in viable air counts (Live bacteria)as i have no way of increaseing the capacity of the AHUs is their anything elce i can do by providing additional equipment to control viable air counts, as the particulate counts seem to be passing at the 3 micron and 5 micron sise my feeling would be that the ac/h may be sufficent??

 

[SAK9]

I have done class 100K cleanrooms with air changes as low as 15.It really depends on what type of work you do inside and the no of people you have.If there are processes which generate dust,you need to identify and address them seperately.

Try to do particle count at a no of places and you will know whether the problem is widespread or limited to few locations only.

 

[davro]

SAK9 thanks for the responce, part of my problem is that its passing on particule or particulate count, its a viable or bacteria count TBCs (total bacteria count i.e. moulds fungas spores etc)that we are failing on and this is fairly wide spread in the cleanrooms, so far ive tried to narrow the root cause but with out success, ive had the clean gowns tested and im getting results of 30-50 cfu with a room spec of 100 cfu , unfortunately i have no base line to compare these with so i dont know if this is a particularly high result for bacteria spores.

 

[IRstuff]

Always look to the people. THEY are ALWAYS the source of particulates in a clean room. With this "increased traffic," I would look at additional training to ensure that the personnel are doing what they're supposed to be doing to stay clean and not contaminate the lab. Training by osmosis is like playing post-office.

I've seen some really stupid things, like people dressing up in Halloween makeup in a Class 100.

TTFN

 

[BronYrAur]

I recently purchased a book called "Practical Cleanroom Design" by Ray Schneider. It gives you a very good general understanding of the do's and dont's.

The ASHRAE HVAC Applications handbook also provides a good cursory review of clean room guidelines.

 

[imok2]

davro, you may want to look at this:

http://www.set3.com/index.html

 

[quark]

When you have controlled number of 0.5 micron sizes and good temperature and humidity control, take it for granted that your capacities are sufficient. 5 microns particle counts are a reflection of the cleanroom discipline.

Class C areas (class 10000 at rest and class 100000 in operation) are specified with a TVC limit of <100cfu/m³ when you are using an air sampler. However, this is not sufficient to establish your viable data. You have to simulatneously take settle plate counts as well. With settle plates of 90mm dia. with an exposure time of 4 hours, the count should be less than 50 cfu. Your count seems to be in limit.

If at all, the problem intensifies, do fumigation once. If you have reservations for formaldehyde, check for Minntech for their disinfectant fogger system.

Have a look at your cooling coils. They are the eternal breeding grounds for living organism.