The Importance of Filtering Compressed Air at the Point of Use

One of our overseas distributors came to us with some pretty good questions regarding compressed air filtration. I thought I would run through that discussion here to demonstrate how important filtering compressed air can be.

To start, the end customer has a fairly straight forward application to blow dust off of large building blocks. The customer has about 5 BARG pressure available at the point of use. Our distributor made a visit to the end customer where they tested a 12” Super Air Knife in the application. The Super Air Knife worked very well to remove the dusty material. So far, so good.

Next, the customer decided to order a 72” version of our Super Air Knife to install permanently into their application. When they installed the Super Air Knife, they did so without inserting a suitable compressed air filter/separator on the line feeding the Super Air Knife. They operated the air knife for some short period of time while checking the operating pressure and feeling the output force generated. It should be noted that the customer did take every other precaution to plumb the Super Air Knife correctly and had a large enough air supply to operate at sufficient pressure level to accommodate the application need.

However, they were not satisfied with the performance of the 72” Super Air Knife once installed and tested. They complained that the force was not high enough and the air flow was inconsistent in velocity. They had even attempted to insert a feeler gauge into the compressed air output slot and mentioned that it would get stuck in some spots.

What happened? The 72” Super Air Knife called for compressed air when energized. And when it did, every bit of debris that had accumulated in the customer’s piping system over the years, broke free and because there was no point of use filter, the debris ended up inside the plenum chamber of the Super Air Knife and in the compressed air slot, thus blocking off a significant portion of the airflow and causing low force condition.

Here is a  photo of the inside of the plenum after initial operation.

20150202_141425
Debris inside plenum

You can see clearly the influx of rusty debris that passed right into the air knife plenum chamber and clogged the Super Air Knife. Given that compressed air moves so quickly through piping, the debris accumulated in the first few moments of operation.

The moral of the story is that no matter how clean you think your compressed air supply is, you should always install a point of use filter up-stream of pneumatic equipment. If this were an air motor or perhaps a solenoid valve, that same debris would have contaminated the moving parts in those systems which would have caused premature and excessive wear that could have been prevented.

What happened with the Super Air Knife? Thankfully, the Super Air Knife does not have any moving parts, so the customer was able to take the Super Air Knife out of service, disassemble it and clean the debris out of the plenum area. Once re-installed and operational with a suitable filter/separator, the customer was very happy with their results gained in the blowing application.

Certainly, this is not how we like to see a new installation go. Unfortunately, this customer had to learn the hard way, how critical a compressed air filter can be. It is easy to overlook such accessory items that are recommended to be installed with a core product. This quick example demonstrates how the small effort of adding compressed air filter/separators can really pay off for good, strong performance right out of the gate and for continued, flawless operation over time.

Neal Raker, International Sales Manager
nealraker@exair.com

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