Buyers’ Guide: What to Know About Buying Compressed Air Dryers
In manufacturing, there are three main utilities that are essential to almost every single process: water, electricity, and natural gas. However, we would argue that there is a fourth utility that several different businesses and industries rely on for daily operations: compressed air.
With that said, a critical part of any compressed air system is the dryer. Compressed air dryers are used to dry the air by removing moisture. This protects vulnerable tools and machinery from water and rust.
In this guide, we’ll cover the importance of managing moisture, how exactly “drying air” works, the various types of compressed air dryers, and some of the most important things to consider before making a purchase.
Managing Moisture
Some level of moisture will always be present because water is present in the natural air. The creation of moisture becomes much easier when air is compressed. When air is under increased pressure, the dew point will rise. The dew point is the temperature at which air is saturated with water molecules. A drop in temperature below the dew point will cause water molecules to condense.
The problem is when there is too much moisture in the air, which can cause rust, corrosion, and contamination. Moisture can wreak havoc on your most vulnerable and valuable tools and machinery. Poorly quality compressed air can even damage your final product or end-use.
It’s critical to manage moisture by limiting it in your air distribution system. Removing moisture from the air can prolong the lifespan of your equipment, and save on repair and maintenance, as well as create a safe, more sanitary workplace for employees.
How “Drying” Air Works
There are a few different ways to dry compressed air, here are four short summaries:
1. Dew Point Manipulation - Manipulating the dew points can dry air. It is done by lowering the temperature to allow condensation to form. Water is discharged and then the air is reheated, drying the compressed air.
2. Over Compression - In this method air is over-compressed and then cooled. Any condensation that forms is removed and then the newly dried air is brought back to normal working pressure.
3. Absorption - This method involved chemically bonding water in compressed air to an absorbent material. The water will dissolve from the material, and then both are discharged.
4. Adsorption - This is another chemical process in which water vapor is bound to adsorption material that can either be solid or liquid. The material is regenerated to regain its drying capacity so that it can continue to remove the water from the air.
Types of Compressed Air Dryers
There are many different types of compressed air dryers that can achieve different dew point levels. Here’s a look at the four most common:
Refrigerated Dryers
True to their name, refrigerated dryers function in a similar way to home refrigerators. A cooling process is employed to prevent moisture — the main difference is the objects, or rather elements, being cool. Kitchen fridges cool and preserve perishable foods and beverages, refrigerated air dryers maintain the quality of air in manufacturing plants.
Of all compressed air dryers, refrigerated dryers are the most popular and widespread type. They are generally inexpensive to set up compared to other air-drying systems. Operation and ongoing maintenance costs are also often lower. These types of drying systems are not recommended for sub-freezing temperatures, as the moisture of air can freeze and damage machinery.
Desiccant Dryers
Desiccant dryers function similarly to the small packet of silica and bentonite gel found inside medicine containers and some food products, both remove moisture from the environment by attracting water to themselves.
This type of air dryer can achieve very low dew points, which is good for pneumatic equipment. There are two styles of desiccant dryers, the most common being silica. The second type is activated carbon. Silica gel desiccant dryers need to be replaced once it is fully saturated, whereas activated carbon can be regenerated.
Desiccant dryers typically operate at reasonable costs and can be used in remote and hazardous environments, but the initial costs can be high.
Membrane Dryers
Membrane dryers utilize filtration systems that first separate moisture and other contaminants from compressed air. The next step involves a membrane that removes any remaining moisture vapor from the air through a process of osmosis. This results in clean, ultra-dry air with a significantly reduced dew point.
Membrane dryers are reliable, efficient, and economical alternatives to other air dryer types. They do not require electricity and are easy and affordable to maintain. For example, the Balston Membrane Air Dryer available from ACI Controls is designed to operate continuously, 24 hours a day, 7 days per week. The only maintenance required is changing the prefilter cartridge twice a year (and that takes about 5 minutes).
Things to Consider Before Buying a Compressed Air Dryer
A compressed air drying system plays an important role in keeping your equipment safe from the effects of moisture. There are several factors to consider to determine which type of compressed air dryer is right for your specific application.
1. The specific uses of your compressed air - Depending on your application and your business, you may need multiple different types of compressed air, which means you’ll need different types of dryers.
2. The desired flow rate - This is essential to sizing a compressed air dryer system properly. Your drying technology and dryer size should complement your compressed air flow rate and air quality requirements.
3. The desired pressure dew point - When buying an air dryer, ensure that the dryer has a higher maximum pressure than your air compressor.
4. The required temperature of the air - Determine the maximum temperature on the hottest day to ensure the dryer is capable of working without overheating or shutting down.
Next, you’ll want to answer the following questions, which will help you to narrow down what kind of dryer your business might need.
1. How often the compressed air will be used?
2. What kind of environment the air compressor is operated in?
Dryer choice is very important in overall system efficiency. A compressed air dryer that is not optimized for efficiency can add to your overall energy bill. However, with the right dryer, the efficiency and overall performance of the manufacturing process can be improved.
Get Clean, Dry Compressed Air
Compressed air is critical to manufacturing, which means compressed air dryers are as well. Managing moisture in facilities is imperative and dryers can help to prolong the lifespan of equipment, as well as save on repair and maintenance. And in addition to creating a safer, more sanitary workplace for employees, air dryers promote high-quality products and minimize compressed air contamination. In some cases, such as humid work environments, an air dryer can mean the difference between stalling operations or moving forward with production — which can have major impacts on revenue.
Find the right compressed air dryer for your specific application today! Reach out to ACI Controls today to learn more.