The right inline air compressor filter solution

Particulates: Particulates in compressed air are small pieces of material like dust, dirt, and/or pollen, as well as loose metal pieces. Depending on the sensitivity of your application and or process, contact with particles can be damaging to the end product. They can also cause delays in production and quality control issues, as well as unsatisfied customers.

Aerosols: Aerosols consist of small droplets of liquid found within a compressed air system, especially in oil-injected machines. Aerosols are created from lubricant. Therefore, oil used in the compressor can be harmful to both products and people if not treated properly.

Vapors: In a compressed air system, vapors consist of lubricants as well as any other liquid that has converted to a gas. Such vapors require a special carbon activated filter in order to be removed from the system.

Now that we have a better understanding of the contaminants above, let us take a look at what types of filtration methods are used.

Polveri: le polveri presenti nelle reti dell'aria compressa sono residui di materiale solido come polvere, sporcizia e pollini provenienti dall'aria ambiente, nonché particelle metalliche derivanti dall'eventuale corrosione dei tubi. A seconda della sensibilità dell'applicazione e/o del processo in questione, il contatto con le particelle può risultare dannoso per il prodotto finale e causare quindi ritardi della produzione e problemi di qualità, per non parlare della possibile insoddisfazione dei clienti. Aerosol: gli aerosol sono costituiti da goccioline di liquido che possono essere contenute nelle reti dell'aria compressa, l'olio in particolare è presente quando si utilizzano compressori lubrificati e, se non vengono trattati correttamente, possono risultare dannosi sia per i prodotti sia per le persone. Vapori d’olio: l’utilizzo di compressori lubrificati determina la presenza di vapori d’olio nelle reti dell'aria compressa. Per la loro rimozione sono necessari filtri ai carboni attivi.

There are three main mechanisms utilized in dry particulate filters to remove solid particles from compressed air. These three forces contribute to the overall efficiency of the filter.

Inertial Impaction: Inertial impaction is a process where particles that are too heavy to flow with the compressed air stream get trapped in the fiber media of compressed air. The larger the particles are, the easier it will be to separate them.

Interception: Smaller particles can follow the air stream. However, if the diameter of a particle is larger than the gap of the filter media, it will get caught by the filter media. This makes it easier to eliminate larger particles than smaller ones.

Diffusion: Diffusion happens when small particles move erratically throughout the surface, instead of following the compressed air stream. This irregular movement path is caused by the particles colliding with other gas particles, an occurrence called Brownian movement. Since the particles have a free-range of motion, it is more likely that they become intercepted and removed by the filter media. Through diffusion, separation of smaller particles is easier than separating larger ones. 

Two types of filters are used to remove aerosols and vapor. Coalescing filters are utilized to remove liquids as well as some particulates, while vapor filters use adsorption to remove vapors from compressed air.

Coalescing: Coalescing filters are used to remove aerosols and particulates, but are not effective in the removal of vapors. The coalescing process consists of bringing small droplets of liquid together in order to form large droplets. As the droplets increase in size, they fall from the filter into a moisture trap, resulting in a cleaner and dryer compressed air stream.

Adsorption: Adsorption is a chemical process used to remove gaseous lubricants or vapors. This process involves vapors bonding with the surface of the media (adsorbent). Activated charcoal filters are commonly used since they attract oil vapor.

As the oil vapor covers the surface of the activated charcoal over time, it is essential to change the filter before it becomes saturated. If not, this would lead to a breakthrough of the oil into the air system.

It is also necessary to use a dust filter after the activated charcoal filter. This is because small charcoal particles could break out and enter the air stream.

To assess the potential damage oil can cause to your compressed air system, it's important to understand your equipment and basic industry requirements. If your industry has strict health codes and or your equipment is sensitive to oil / vapor exposure, it is crucial to use proper filtration.

Let’s take a closer look at lubricants and understand the effects they can have on your end product. Similar to particulates, lubricants can enter your compressed air system from ambient air as well as from the compressor itself. Facility operations, like a motor exhaust, release hydrocarbons like oil aerosols into the ambient air, which can compromise air quality and cause equipment failure.

Oil injected air compressors will also release lubricants into the compressed air system, resulting in increased operational and maintenance costs. Industries such as electronics and semiconductor are especially exposed to lubricant contamination, which can result in product loss, missed deadlines and unsatisfied customers.

Poor filtration usually causes pipe corrosion, increased pressure drops and can cause equipment damage, resulting in costly downtime and unexpected repair costs. Corrosion can also cause excess debris in your piping system, which in turn results in your compressor working harder. This leads to higher energy consumption and excess wear on compressor parts.

Proper filtration is key in achieving desired results when strict codes or purity classes are enforced. The only way to fully protect your product from unwanted oil in your compressed air system is to utilize oil-free compressors. This type of technology eliminates the risk of contamination, resulting in clean, high quality compressed air.

Per estrarre dall'aria le particelle solide di ogni dimensione, i filtri per particolati secchi utilizzano tre meccanismi principali. Impatto inerziale: l'impatto inerziale è un processo in cui le particelle troppo pesanti per seguire il flusso di aria compressa rimangono intrappolate nel supporto in fibra. Quanto più le particelle sono grandi, tanto più è facile separarle. Intercettazione: le particelle più piccole riescono a seguire il flusso d'aria, ma se il loro diametro è maggiore delle dimensioni dei vuoti del supporto filtrante, il medesimo le cattura, agevolando l'eliminazione delle particelle più grandi rispetto a quelle più piccole. Diffusione: si verifica una diffusione quando le particelle piccole si muovono in modo irregolare su tutta la superficie invece di seguire il flusso dell'aria compressa. Il percorso seguito durante questo movimento irregolare è causato dalle collisioni fra le particelle e altri costituenti gassosi, un fenomeno detto moto browniano. Poiché le particelle hanno un intervallo di movimento libero e possono muoversi liberamente, è molto più facile e probabile che vengano intercettate dal supporto filtrante ed estratte dal flusso di aria compressa. La diffusione consente di separare le particelle più piccole con maggiore facilità di quelle più grandi La combinazione di queste tre forze determina l'efficienza complessiva del filtro