Basics for compressed air dryer sizing
How to select a compressed air dryer?
Moisture is one of the main “enemies” of compressed air for two reasons:
- When ambient air is compressed, the moisture remains, which means that there is always a lot more moisture in untreated compressed air than in the air that surrounds us.
- Moisture by itself can cause damage to a compressed air system, downstream equipment and end products, for example through corrosion. In addition, it can also lead to the growth of microorganisms, such as bacteria, that can have devastating effects on operations in many industries, such as the food & beverage sector.
With the proper drying technology, however, you can eliminate these risks and protect your compressed air system, your equipment and your end products.
Know your air quality requirements before selecting a compressed air dryer
Moisture in compressed air should always be treated as a potential problem that can, at the very least, reduce the durability of your compressed air equipment.
There are many cases, however, in which certain air quality standards have to be met. Most often, these are industry specific. Whenever compressed air comes in touch with sensitive products, such as food and beverages, pharmaceuticals, electronics, etc., it has to be especially pure to prevent them from spoiling, corroding, etc.
Failing to do so may not only result in penalties but could also lead to production shutdowns, having to discard products, recalls or worse.
That is why the very first step in air treatment is finding out which level of air quality is required or mandated for your application. To do so, you should consult ISO 8573-1 (ed. 2010) – the most important international air quality standard. It is divided into seven air quality classes to help you figure out how clean your air has to be.
Determine the pressure dew point
To find the air purity class that applies to you, you have to determine the pressure dew point (PDP) of your compressed air.
It describes the water content in your compressed air. Specifically, the PDP refers to the temperature at which water vapor condenses and turns into water at the current working air pressure.
Removing this moisture requires the use of a dryer. However, there are many different technologies available to you, so which one should you choose to safeguard your production processes and your products?
Once you know the required air purity and your PDP, you can figure out the drying equipment and optimal drying method.
And, if you are unsure about the air quality your application has to meet, how to calculate your PDP, or if you have any other questions, you can also contact us, and your local sales representative will be happy to assist you.
The best (and simplest) way to choose the optimal dryer technology for your operation is to determine the dew point requirements of your application.
For example : if it is below 3°C (37.4°F), then you will likely end up with a desiccant adsorption dryer. In this type of dryer, the moisture-containing air flows through a desiccant – which could either be thousands of tiny beads or our revolutionary Cerades™ solid desiccant – which absorbs and retains the moisture.
If the dew point requirements are less stringent, then you can probably work with refrigerant dryers. As the name indicates, they use a refrigerant to remove humidity from compressed air.
In general, the lower the dew point has to be, the more energy has to be expended to achieve it, which obviously affects the operating costs.
This is also why all of our dryers are designed to be extremely energy efficient. For example, because heat is a byproduct of compression, some of our desiccant dryers use that heat as a source of energy to reduce your costs.
This heat recovery process allows dew points as low as -40°C/°F to be achieved without adding any substantial amount of energy.
Obviously, desiccant dryers can also be used for applications that require a higher dew point and where a refrigerated air dryer would suffice.