Filters for getting Instrument air & Mask air

by Vilas Nale
(India)

We have Centralised compressed air plant supplying Instrument air & Mask/service air for use in power plant. The mask air & inlet to dryers supplying instrument air is tapped off from outlet of common air receivers. The requirement of both type of air is similar i.e.20Nm3/min. The requirement of filters for Mask air is of 3 micron rating whereas those for instrument air is of 5 micron rating as per international standards.

I would like to know whether we can make both filters of 3 micron rating to have standardised filter elments for both type of filters.

What will be the effect on O&M of filters for dryers? What are the penalties or advantages of making both filers of 3 micron rating?

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Bill says...

As far as I am concerned, there is absolutely no negatives to supplying cleaner air to any application, whether instrument air, or to run an air tool or cylinder.

The issue for you will be cost to maintain the 3 micron system and getting 3 micron compressed air filters that have enough flow rating for your applications.

General purpose compressed air filters run around 30-50 microns in element size.

You should always install a general purpose filter upstream from a finer filter element, including your 3 micron filters, as the general purpose filters strip larger contaminants from the compressed air before they can get to, and quickly plug up, the finer size of the element in the 3 micron filter.

As long as you are satisfied with the maintenance issues regarding just using 3 micron filters, go ahead.

I suspect that you'll be changing them out quite often, though. And do make sure you have some sort of delta P gauge on the filter so you can tell when the element is becoming plugged, and before you starve your applications for air.

Cheers,

Bill