7 replies to this topic

[isabelle campbell]

Good Morning from Canada!

I work in a food manufacturing plant that used compressed air to operate, clean and dry machinery. The air used to clean and dry the machinery comes from a dedicated and specially fitered source (0.01 micron for particulate and .1 for oil and water) for use on direct food contact surfaces and it is tested for aerobic plate count on a monthly basis.

We have been getting results showing less than 10 colonies (each in 6 various "ports" tested). We have data over several months since and very occassionally the results are as high as 24 colonies. I can't find any literature to help me decipher the results. My questions are!

• should there be any colonies?
• should yeast and mold tests also be conducted?
• where is the literature on industry standard?

Thanks in advance!
Isabelle Campbell

[Saurabh]

Hello,
I think the tests you are currently performing should be sufficient. But again, it all depends on following :
Is the compressed air coming in direct contact of product ?
If yes, does it come in contact at pre-processing or post-processing step ?
Do you have a scheduled maintenance for filters (i.e. inspection and replacement) ?
At one of the previous company I worked with, our compressed air used to come in direct contact of product (after processing) but since we had a scheduled maintenance for filters (replace filters after 3 months) which was strictly followed and documented, we never tested the compressed air and non of the auditors ever raised any questions. However, we use to do environmental counts on regular basis.
You are getting counts after 0.01 micron filter shows that the filters are damaged.
I hope I was of little help.

Good Morning from Canada!

I work in a food manufacturing plant that used compressed air to operate, clean and dry machinery. The air used to clean and dry the machinery comes from a dedicated and specially fitered source (0.01 micron for particulate and .1 for oil and water) for use on direct food contact surfaces and it is tested for aerobic plate count on a monthly basis.

We have been getting results showing less than 10 colonies (each in 6 various "ports" tested). We have data over several months since and very occassionally the results are as high as 24 colonies. I can't find any literature to help me decipher the results. My questions are!

• should there be any colonies?
• should yeast and mold tests also be conducted?
• where is the literature on industry standard?

Thanks in advance!
Isabelle Campbell

[Foodworker]

It does seem odd that you are getting any count after using a 0.01 micron filter when you relate the size of bacteria to this. I have to say that monthly testing is more frequent than most companies that I have come across.

Points to consider:

Is the filter at point of use or at the compressor itself.
Where is the filter(s) in relation to the sample points.

You can get microbial growth within the compressed air pipework, particularly if it is designed on a ring main basis.

Check for dead legs in the pipework.

Mould spores do germinate in compressed air pipework, but if the filter is at point of use this should not be a problem.

Clarify how the engineers/contractors monitor the air filters. In my experience, engineers look at a dial/gauge and change the filter when it goes into the 'red' or blocked zone. From a food safety perspective rather than an engineering view, the danger is the reverse ie when the filter has broken down and the pore size is no longer as small as it was when installed. When the filter breaks down, the guage will not show as blocked and they may not change it. Before and after differential pressure gauges will show if the filter has broken down.

There are a couple of relevant(ish) ISO Standards - ISO8573 for compressed air and ISO 12500 for air filters. I don't have copies unfortunately.

There is another grade of filter commonly called "medical grade" which may be appropriate depending upon your application

[Trace Analytics]

Good points raised here.

Compressed Air Testing can assist the manufacturer in several ways.

• Proving or disproving that your filters are working properly
• Showing if you have an issue with your system and the air being used for your product, pre or post filter
• Assisting with narrowing the location of the actual problem

Contamination can happen anywhere in the system as pointed out previously. Filters are great but they can fail and/or something can go wrong after the filter. Testing at the point of use is the best way to see what is actually happening where the air is finally used. Also, each point of use can have a different result. Just because one point of use performs as intended does not mean they all do. This is why testing all points of use should be implemented even if it is on a rotation basis.

ISO 8573 is a great spec to refer to and possibly the most comprehensive on the subject. I would be interested in any other comprehensive specifications on the subject if anyone knows of any.


As far as the original poster's questions:

• should there be any colonies? No, if there are you should identify them to assist in determining your problem
• should yeast and mold tests also be conducted? Yes
• where is the literature on industry standard? http://www.webstore.ansi.org/ You can type in ISO 8573 and find it.
  

It does seem odd that you are getting any count after using a 0.01 micron filter when you relate the size of bacteria to this. I have to say that monthly testing is more frequent than most companies that I have come across.

Points to consider:

Is the filter at point of use or at the compressor itself.
Where is the filter(s) in relation to the sample points.

You can get microbial growth within the compressed air pipework, particularly if it is designed on a ring main basis.

Check for dead legs in the pipework.

Mould spores do germinate in compressed air pipework, but if the filter is at point of use this should not be a problem.

Clarify how the engineers/contractors monitor the air filters. In my experience, engineers look at a dial/gauge and change the filter when it goes into the 'red' or blocked zone. From a food safety perspective rather than an engineering view, the danger is the reverse ie when the filter has broken down and the pore size is no longer as small as it was when installed. When the filter breaks down, the guage will not show as blocked and they may not change it. Before and after differential pressure gauges will show if the filter has broken down.

There are a couple of relevant(ish) ISO Standards - ISO8573 for compressed air and ISO 12500 for air filters. I don't have copies unfortunately.

There is another grade of filter commonly called "medical grade" which may be appropriate depending upon your application

[LSS-QA]

Good Morning from Canada!

I work in a food manufacturing plant that used compressed air to operate, clean and dry machinery. The air used to clean and dry the machinery comes from a dedicated and specially fitered source (0.01 micron for particulate and .1 for oil and water) for use on direct food contact surfaces and it is tested for aerobic plate count on a monthly basis.

We have been getting results showing less than 10 colonies (each in 6 various "ports" tested). We have data over several months since and very occassionally the results are as high as 24 colonies. I can't find any literature to help me decipher the results. My questions are!

• should there be any colonies?
• should yeast and mold tests also be conducted?
• where is the literature on industry standard?

Thanks in advance!
Isabelle Campbell

I'm curious as to how you are collecting the compressed air micro sample. Is there a special aparatus for this? Any help you could give would be greatly appreciated. Thanks.
Brant

[Ruby Ochoa]

There are a few samplers on the market for compressed air. Look for the ones that have a diffuser that can be attached for sampling compressed air. I have a list of about 5 or 6. Send me an email & I'll be glad to forward to you.
Ruby

I'm curious as to how you are collecting the compressed air micro sample. Is there a special aparatus for this? Any help you could give would be greatly appreciated. Thanks.
Brant

[Reiljames12]

Is is considerable to do bubbling on sterile buffer solution to do micro test?

 

[Charles.C]

Is is considerable to do bubbling on sterile buffer solution to do micro test?

 

Hi Reiljames,

 

Please note this is a 6-year old thread. Unfortunately the methodology used for data in OP was never revealed.

 

afaik Standards (eg limits) for air in food process environments only exist in certain defined cases. Some commercial 0.01micron filter sets are claimed/validated to be capable of producing sterile/near sterile air outflows.

 

the usual standard methods for air micro. analysis involve impact or sedimentation techniques. Both are discussed in later threads here.

 

I have never seen yr idea in print ? Was it just a suggestion ?