Refrigerant Air Dryers, condensate traps or what?

[zsadiq]

Hello Friends,

We are running our air compressor in hot and humid environment (35 celsius 75% RH). Currently no air dryer is being used and we are planning to purchase one. But till we buy it, can we use condensate traps to save pneumatic appliances from condensate . Moreover, please tell me if condensate traps can do the job, why should we opt to buy an air dryer?
Another question. We are a Pharmaceutical Industry, so what kind of air filtration should we use on air compressor. Compressed air does get in touch with the product but after filteration as per GMP. So mostly the air is running pneumatic equipment. So should we use filters to remove particles and oil on main lines. Actually I'm looking for a criteria for Compressed Air Quality for various applications.

 

[freefallingbody]

Zsadiq,

Compressed air need drying to avoid condensation at distribution systems and the points of use. Condensate which is formed when compressed air is stored in a receiver can be removed by using a condensate trap. But that is not sufficient.

When air is compressed, it has a capacity to retain more moisture than when it is at atmospheric pressure. So, when compressed air is expanded to atmospheric pressure, the moisture which is not removed the after cooler and a condensate trap will get condensed at the end use and create problems. So you need a dryer.

The dryness of air required is generally given as dew point. Typically, a refrigeration type dryer can reduce teh temperature of compressed air to 6 to 7 deg.C ( pressure dew point) which is equal to -20 deg.C atmopsheric dew point. You have to use dessicant dryers for -40 Deg C dew point onwards.

There is an ISO 8573.1 standard for quality classes. Microelectronics manufacturing falls under class 1 for dirt ( 0.1 microns), water( pressure dew point of -70 deg. C) and oil ( 0.01 mg/m3). This is the cleanest manufacturing area under this standard. Some other applications, the values are as follows.

Dirt Water Oil
Food & beverages 5 microns -70 deg.C 0.1 mg/m3
Instruments 1 mincron -20 deg.C 0.1 mg/m3

I do not have information on pharmaceutical industry. You may get a copy of the standard for further info.

Regards

A.V.Dinesh
Devki Energy Consultancy P. Ltd.,
Vadodara, India

 

[cme]

Refrigerated air dryers work best at full load.

Anybody here apply a medical grade air dryer to this or control service?

 

[imok2]

With Pneumatic controls refrigerated air driers is a must. The more delicate the end result the more filtration and dry you need the air to be. Pneumatic controls have restrictors as small as 0.005".Even if the end result is not that delicate, it's still better to keep moisture out of your air lines.

 

[quark]

Hot gas bypass type refrigerated air dryers can give you a pressure dew point of +3[sup]0[/sup]C continuously. Try Sabroe, Parker Hannifin and Domnick Hunter etc. As far as pneumatic components are concerned, better go with desiccant dryer as suggested by freefallingbody. Activated alumina type will give you -40[sup]0[/sup]C ADP.

As far as pharmaceutical plants are concerned, you should use a sterile grade filter (0.22micron of Pall, Millipore and Sartorius etc) for compressed air, if used in parenterals. It is not a problem for OSDs but still we use 0.01 micron filter of Domnick Hunter (equivalent to the above said one)

You should always go for a nonlube type air compressor. You should provide condensate traps to the receiver and distribution system where ever there are risers. But these traps will take care of the moisture seperated from the air.

Like Freefallingbody explained, moisture in the air gets condensed when the temperature goes down. This is always possibel when you are expanding the air while using it.

Go to Domnick Hunter website to get some guidelines on compressed air.

 

[zsadiq]

Thanks for all the support. Please tell me if the manufacturers of pneumatic instruments and automation tools (like festo etc.) specify ISO Class for the compressed air that should be used for the instrumentation. I've tried to search it through their websites but I couldn't find anything over there.