Compressed air contaminants can cause severe problems.
For example, a contaminant reaching a final product in manufacturing will nearly always compromise quality.
The gold standard is to consistently produce dry, clean, compressed air without any water vapour, particles, or aerosols present!
Fortunately, there is a range of excellent filters available, all of which remove compressed air contaminants, albeit with different functions and applications.
We’ll explain how to remove those compressed air contaminants in this guide – and why it’s so vital!
Consider air compressor maintenance to take take of this issue for you.
Using Compressed Air Filters to Remove Contaminants
The first option is to think about filtration. Filters are made with contemporary fibres that are designed to trap oil.
However, one of the challenges here is that oil filtration is affected by:
- The temperature of the air.
- The concentration of oil present.
- How much water vapour is present.
Filter specifications always mention temperature – so you need to choose a filter suited to the air temperature present.
Fluctuations in heat owing to the time of year, amount of time your compressors are running, and other production processes all impact the separation capacity of your filter and change its efficiency at removing compressed air contaminants.
It’s also important to consider the potential contaminants present and what type of filter is best suited – for example:
- Pre-filters and fibre filters combined can reduce oil quantity to around 0.01 mg per cubic metre.
- Activated carbon filters remove oil to around 0.003 mg per cubic metre.
Carbon can absorb up to 20% of its weight in oil, but it all depends on the concentration of compressed air contaminants you need to remove.
Filters with a small carbon powder coating have a limited lifespan and can only operate in reasonably cool temperatures. Bulk activated carbon bead filters, in contrast, contain much more carbon and so last longer and are suitable at higher temperatures.
How Does the Dryness of the Air Impact Filtration?
Ideally, the air should be as dry as possible.
Free water in the air means that sterile filters, oil filters and activated carbon filters cannot operate correctly, so it’s crucial to dry the air and filter it.
One of the best ways to achieve this is with an after-cooler, which reduces the compressed air temperature and, therefore, reduces the water content.
Most compressors will include an after-cooler, or you can install the cooler directly after the compressor.
After-coolers can be cooled by water or air and often feature a water separator offering automatic drainage of the water vapour collected.
What Does a Water Separator Do to Help Remove Compressed Air Contaminants?
We’ve discussed after-coolers, but a water separator is another helpful tool, separating as much of the condensed water as possible.
These components can operate up to around 90% efficiency, reducing the water mist substantially.
How Can I Separate Oil and Water in My Air Compression Processes?
Oil droplets are partly separated in the after-cooler. You can also use a condensation separator or condensation tap.
It’s essential to dispose of the eliminated compressed air contaminants correctly – the combined water and oil emulsion is an environmental hazard, so you can’t drain it through the usual sewage system.
Oil/water separators are a cost-effective solution, usually with a diaphragm filter, which drains off the oil into a receiver allowing clean water to drain away.
What Are the Medical Purification Options to Eliminate Compressed Air Contaminants?
Air compression processes in the medical sector must perform to high degrees of air purification.
Quality air, free of compressed air contaminants, is crucial, and air used in hospitals or medical facilities must be 100% pure.
There will always be contaminants in ambient air, given that water vapour and other particles occur naturally.
Medical air purification uses several stages to ensure there are no compressed air contaminants present, such as:
- Incorporating two coalescing filters, plus a water separator, to remove water, oil and particles.
- Transmitting filtered water to a cold regenerative adsorption dryer. The dryer reduces the dew point to sub-zero temperatures required for medical applications.
- Following this stage, the air is filtered again. Next, an activated carbon filter removes any hydrocarbons (such as oil vapour). A catalyst then converts any excess carbon oxide into carbon dioxide and reduces other contaminants to minimal levels.
- Finally, a particle filter removes any remaining dust particles entering the air stream through the dryer or during the additional filtration stage.
These different filtration processes are required where compressed air contaminants pose a significant risk – which can relate to other manufacturing processes where products being made must not be exposed to anything but completely clean, dry air.