Contamination in Class100kclean room 2

[SAK9]

I am investigating a contamination problem with a class 100000 clean room for a pharamceutical plant.I would like to know what is the filtration level requirement for compressed air used in the space.What is the recommended practice for disposing air released from machinery actuators
Will a house vacuum system help improve the particle count?I would greatly appreciate any help from any of you out there.Thanks in advance!

 

[91479184]

Normally compressed air for clean room facilities should be cleaned and dried.For cleaniness of air,HEPA filters(filtered 0.3micron) are installed at the outlet of dryers.For dryness, dryers could install at the air receiver outlet.For a good practice, clean rooms's operating parameters are room pressure(+ 10 ~ 30 Pa), humidity (55%), room temperature (24C).House vacuum is just to suck the dust and rubbishes in the clean room. For your problem, I would suggest to check the room condition and activities in your clean room. Some process machines may generate particles.

 

[quark]

SAK!

I totally defer with the above post. HEPA filters are used for HVAC applications and not for compressed air. Generally air from pneumatic equipment is exhausted by sintered brass exhaust filters. (upon my discussion with Festo I was told that they are of 10 and 20 micron size)

At end use 1 and 0.01 micron filters of micro glass fibre (or borosilicate glass fibre) are used. One good manufacturer is Domnik Hunter of UK. The reason for
0.01 micron, eventhough you have to restrict 0.5 micron or above, is fine water particles are coalesced and collected in the filter bowl which is drained off. Moreover these filters give sterile quality to air. Prior to this you have to use some prefiltration. (preferably 20 and 5 micron)

You need not go for HEPA(EU 11 or 12 filters) for class 100000. EU8 and 9 are sufficient.

Vacuum cleaning system does help you but not a domestic one because you have to use HEPA filters in the exhaust of vacuum cleaner. (They are available in market)

Regards,

 

[quark]

One more point is Federal Standart 209E is taken back and now not in practice. (That is the document which gives clean room description in classes viz. 1, 10, 100, 1000, 10000, 100000 etc. Now ISO standard is in practice. The classification is ISO1, 1.5, 2, 2.5 etc.

Regards,

 

[SAK9]

Hi Quark and 91479184,

Thanks for your helpful posts.I found out this particular space has an air change rate of 15.Fine filters are provided in a filter plenum after the AHU and there are no terminal HEPA filters.The space is used for manufacturing plastic syringes.When I referred to GMP guidelines it seems to recommend minimum air change rate of 20 for Grade D areas(class 100000)and terminal HEPA filters in the air distribution system.Any thoughts?

Please find attached below relevant extract from GMP guidelines(

http://www.who.int/medicines/organi.../qualityassurance/gmp/gmpthree.html#Sterile):

Table 1. Air classification system for manufacture of sterile products


Grade Maximum number of particles permitted per m3 Maximum number of viable microorganisms permitted per m3
0.5–5 mm >5 mm
A
(Laminar-airflow
workstation) 3 500
none less than 1
B 3 500 none 5
C 350 000 2 000 100
D 3 500 000 20 000 500


17.2 The various operations of component preparation (such as containers and closures), product preparation, filling, and sterilization should be carried out in separate areas within the clean area.

17.3 Clean areas for the production of sterile products are classified according to the required characteristics of the air, in grades A, B, C, and D (see Table 1).

To obtain air of the required characteristics, methods specified by the national authorities should be used. It should be noted that:

• Laminar-airflow systems should provide a homogeneous air speed of about 0.30 m/s for vertical flow and about 0.45 m/s for horizontal flow but precise air speeds will depend on the type of equipment.

• In order to reach the B, C, and D air grades, the number of air changes should generally be higher than 20 per hour in a room with a good airflow pattern and appropriate HEPA (high-efficiency particulate air) filters.

• Low values for contaminants are reliable only when a large number of air samples are taken.

• The guidance given for the maximum permitted number of particles corresponds approximately to the United States Federal Standard 209E (1992) as follows: Class 100 (grades A and B), Class 10 000 (grade C), and Class 100 000 (grade D).

It may not always be possible to demonstrate conformity with particular air standards at the point of fill when filling is in progress, owing to the generation of particles or droplets from the product itself.

17.4 Each manufacturing operation requires an appropriate air cleanliness level in order to minimize the risks of particulate or microbial contamination of the product or materials being handled. Section 17.5 gives the minimum air grades required for different manufacturing operations. The particulate and microbiological conditions given in Table 1 should be maintained in the zone immediately surrounding the product whenever the product is exposed to the environment. These conditions should also be achieved throughout the background environment if no personnel are present in the processing area, and if the standards fall for any reason it should be possible to recover the conditions after a short "clean-up" period. The utilization of absolute-barrier technology and automated systems to minimize human interventions in processing areas can produce significant advantages in ensuring the sterility of manufactured products. When such techniques are used, the recommendations in these supplementary guidelines, particularly those relating to air quality and monitoring, still apply, with appropriate interpretations of the terms "workstation" and "environment".

Manufacture of sterile preparations

17.5 Manufacturing operations are here divided into three categories: first, those in which the preparation is sealed in its final container and terminally sterilized; second, those in which the preparation is sterilized by filtration; and third, those in which the preparation can be sterilized neither by filtration nor terminally and consequently must be produced from sterile starting materials in an aseptic way. Area grades as specified in sections 17.5.1–17.5.3, must be selected by the manufacturer on the basis of validation runs (e.g., sterile media fills).

Terminally sterilized products

 

[quark]

SAK9!

The classification of ABCD is very much well defined in Orange Book of MCA (UK). They have also provided brief description of what areas should be what. (like asceptic and non asceptic filling, storage, sealing and manufacturing etc.)

For a typical class 100 000 area USP specifies around 20 air changes. As I have experience with clean rooms uptill class 100 areas (ofcourse in Laminar Air flow hoods), 20 air changes are sufficient for class 100 000 areas. Earlier there were filters designated by 3micron, 5 micron etc which are called fine filters. Because of non availability of particle counters people used to presume the cleanliness of the area. When we checked up with MetOne make particle counter, we found some problems. Now the trend is using
EU-8 or 9 filters for class 100 000 areas which have efficiency of 90 to 95% at 0.5micron. (duct installation will suffice the requirement) and we got very good results. If you know the particle generation in the area and select the filter size accordingly then you get better cleanliness.

Note: I am very much ready to help you further.

Regards,

 

[SAK9]

Quark,

Many thanks for your post.I have done a particle count test in the area and the results indicate non compliance in couple of locations( overall area of 60400 sq ft).The count of 0.5 micron particles in these locations range from 135000 to 176000.The rest of the space have a count ranging from 70000 to 85000.The machines in the non compliant locations appear to be causing the high particle count of 0.5 micron( The count of 5 micron particle is below 100 in most places).What in your opinion is the best solution to this problem?I am thinking of a local exhaust(some thing similar to a dust extraction system) near these machines .I would also like to add that the clean room is about 355ftlong x170 ft wide.The two rows of return grilles(one at ceiling level and the other at low level) are located at the two ends of the room and they are also about 170 ft apart.Do you think more return grilles are required in between ?I look forward to your reply.

 

[IRstuff]

One solution that is often done is to enclose the machinery with a plastic air curtain or hood with sufficient suction to remove the particulates before they get out to the general work area.

Likewise, critical workareas are often placed under hoods that provide Class 100 environments within the hood. In some moderate tech facilities, the main room was Class 10,000, with work areas under hoods at Class 100. The hoods draw air from the room and run it through a local HEPA filter and the back wall of the hood exhausts the air into the main room recovery path or to scrubbers if there are toxic fumes, etc.

Seemed to work pretty well 20 yrs ago ;-)

TTFN

 

[quark]

SAK!

Localised exhaust is a cheaper option and good. Generally for Form Fill Seal machines which use LDPE plastic the particle generation was estimated at 1Million/minute. (Don't know whether it is exaggerative or not). IRStuff has given a good idea. (Ofcourse now it is very famous as Isolation technology for contained areas)

Secondly in clean rooms it is better to take return risers (from bottom). Try controlling the ceiling dampers so that the air returns from bottom.

Further check the integrity of filters (by pressure drop).

Regards,

 

[SAK9]

Hi Quark/IRStuff,

If I were to do a local exhaust or a plastic curtain with around the machinery,can I put the exhaust air back into the return air stream?This would save me some energy.If yes, is it better to have it filtered seperately before sending to the AHU or the let the AHU filter take care of it? Look forward to your suggestions!

regards

 

[ChasBean1]

Sak9, depends on the material exhausted - does it contain volatile organic compounds or just particulate? Is there odorous offgas? Does it bleed at high velocity to a location that can gather dust?

From your original post it seems that your source is air bleed from pneumatic actuators. Have you considered a total control system switch-over to electric actuators?

Just some thoughts to throw in the mix, not meaning to change or detract from the good suggestions already by Quark and IR. -CB

 

[IRstuff]

Ditto, as a general rule, any air that is potentially contaminated, by fumes, VOC's, etc. should be sent through a scrubber.

In our case, many of our hoods housed acids and their associated fumes, which were quite toxic, so they had to be scrubbed.

Machinery with low air contamination under air curtains were allowed to return air into general return plenum, which still needed to pass a HEPA filter before it returned into the room.

TTFN

 

[quark]

SAK9!

The new cleanroom regulation ISO 14644 clearly says a class 100 000 clean room need not have a HEPA filtered area. If your specification of the manufacturing area falls under the category 'D', then in 'Operation Condition' there is no restriction for particle count and it should be class
100 000 in only 'Rest' Condition. Unfortunately I couldn't find out for your type of facility.

You can always recirculate the air back into the room and it is a general practice. Use Laminar Air flow hoods which come with pre and HEPA filters. These will take air from inside and recirculate there itself.

For any particle size limit in a particular area you can use the formula N = Nc(0.5/d)^2.2 where N is number of allowed particles and d is the mean diameter of a particular size.

Regards,

 

[SAK9]

Dear All,
Thank you for all the posts .With your help ,I should be able to put this problem to rest.Quark,you have given a very intersting lead in your latest post regarding ISO14644 regulation applicable to Grade D/Class 100,000 areas( I believe they are the same ).I need to explore this further.If this is applicable to my case,I may not have to do anything!

Best regards

 

[irfanbaig36]

Could someone tell me about class 1000 cleanroom filteration upstream and downstream of air handler?

 

[Ramses1957]

Can anyone tell me what the new class is for a (ISO 8 Class Air Filteration.)