Dew Point of Compressed Air

Dear Experts,

Please guide If in an OSD facility
(Class-D) if we are maintaining Dew point of compressed air is between -32 Deg. Celsius to -40 Deg. Celsius and we are recording it in the log books of air dryer ,
My question is whether it is within the required limit as per regulatory requirements or it is a non -compliance.
because in the ISPE good practice guide for Process gases dew point limit is less than equal to -40.

So we are in a state of confusion, please give your valuable feedback.

Parveen Garg

Hi Parveen,

you should understand that there is a difference between regulatory requirements and what instances like ISPE specify.
Typically regulatory states what you need to achieve but rarely specifies HOW you need to achieve it.

Organisations such as ISPE try to translate the theory into practice. The laws and rules being the theory, and more hands on (even technical approaches) being the practice. ISPE tries to work together with regulatory instances and on the other hand brings together the knowledge of different industries. these two combined provide for all users a knowledge database.

What I try to say is, use the forum as an input that can help you to solve your problems.As with many things different solutions can be applied to solve one problem. And regulations will accept different solutions as long as you can prove that you are in line with the regulations. Even between big companies that support ISPE you will find differences in approach of similar systems.

To your question. The low the dewpoint the dryer the air.
Question you should ask is Depending on the use of CDA. The more critical the process the less you want to disturb it, and the cleaner you want your CDA to be.

But the process to make clean air is as important as the the claim you want o make, and then you need to talk to your compressor provider and he will start talking about technical norms (nothing to do with pharmaceutical regulatory bodies). In this case he will talk about ISO 8573.

So depending on your ciritical processes, set your requirements: setpoint andalarm ranges.
Then setup your testing scheme and proof that your system is within spec.
The only advise I can give is that you better not set your specs on the working limit of your compressor. You may find that you will have regular excursions.



Thanks Johan,

Please tell me whether it is acceptable that Dew point between -35 to -40 as per ISO 8563

Parveen Garg

First off, are you using the most up to date version of the ISO standard? It was updated in 2010 (previous was 2001). Also, there are various air quality classes in the standard from 1-6, which one have you stated you will adhere to, or is there one your regulators/customers expect that you are compliant with?

Thanks dear ,

It will help me a lot.

Thanks once again