A refrigerated compressed air dryer is a type of air dryer that is used to remove moisture from compressed air. Compressed air often contains moisture that comes from the air sucked by the air compressor.Such water and oil can damage the compressed air piping system, and therefore you need acompressed air dryer.
Air Compressor Dryer Installation Diagram
Air Compressor Dryer Installation Diagram
Why a refrigerated compressed air dryer?
Refrigerated air dryers are among the most used types of air dryers for air compressors. They come in a simple design and require minimal maintenance. Additionally, they are more cost-effective than other types of compressed air dryers.
A refrigerated air dryer should be the standard choice if you need an air dryer that does not require specific features, such as very low dewpoint. As said before, refrigerated air dryers do not require special maintenance, and as long as you get a quality one and have installed in the right way, you will be in the set-and-forget mode for a very long time. There is a takeaway here. You need to have the air dryer appropriately installed for it to work efficiently and prolong the life span of your air compressor and air tools. So, what is the right way to install an air dryer? Do not worry; we will look into that shortly. But before we go into how to install the compressor air dryer, we need to understand what and air dryer is and how it works.
How does refrigerated air dryer works?
As the name goes, a refrigerated air dryer works by cooling compressed air. Warm wet air enters the dryer, where it gets cooled down to 3 degrees Celsius for moisture (water vapor) in the air to condense into water. The condensed water is then trapped using a water trap and removed from the compressed air system. The cold air is then entered into room temperature. The remaining air is now free from moisture (dry air) of any kind since the water has been trapped out. The cooling effect happens in the same way that your cooler or refrigerator would work. Liquid refrigerant goes through an evaporator and is evaporated to cool down the warm air from the air compressor. This process happens in a separate circuit.
As the compressed air gets cooled down, the refrigerant becomes warm. Thus, to cool the refrigerant down once again, it is compressed by a small compressor in the condenser. The evaporator, which is the place where the refrigerant cools down warm compressed air, is found at the top part of the air dryer. In most cases, you will see a cooling fan close to the condenser.
Types of refrigerated compressed air dryers
There are two types of refrigerated air dryers; cycling and non-cycling air dryers. A cycling air dryer is beneficial in the sense that it increases or decreases the cooling capacity according to compressed air demand. This makes it more energy-efficient and cost-effective. On the other hand, the non-cycling air dryer is the most used one because it requires less maintenance and is extremely reliable.
What to look for when buying one?
There are some essential factors to keep in mind when shopping for a refrigerated air dryer. Here are some of the key points:
The maximum pressure:
You have to ensure that the maximum pressure of your refrigerated air dryer is the same or slightly higher than the maximum pressure of your air compressor.
The maximum rate of airflow through your compressed air dryer must be higher than what is delivered by your air compressor. Going for a too-small air dryer will cause massive pressure drop over the dryer, due to this reason you need to adjust the pressure on your air compressor higher to compensate for the pressure drop. This would mean incurring high costs in energy bills. Additionally, the dryer may not be in a position to reach the required dewpoint.
The air dryer comes with a specified inlet temperature that you have to take a keen interest in. If you go above the recommended temperature, some parts of the air dryer may be damaged all the entire system will fail and therefore not achieve the desired dewpoint. Some air compressors come with an aftercooler installed in their system.
In this case, the compressed air will be somewhere around 40 degrees Celsius. Without an installed aftercooler, the compressed air can be as high as 80 degrees Celsius and above. You need to check the temperature of compressed air, leaving your air compressor. If it is scorching, then you can go for some special high inlet temperature dryers found in the market. These are specifically designed to work in such hot air conditions.
Maximum outside temperature:
Do you need to work with your air dryer in hot conditions? The chances are that your air dryer will overheat and shut down. You need to find out the maximum temperature that your air compressor can work in and buy an air dryer that can handle such temperature ranges.
Air Dryer Maintenance and Installation
For installation and maintenance of your air dryer, always check your user manual for guidelines. Every make and model of a refrigerated air dryer has its specific needs and instructions. However, there are general things that you can keep in mind when it comes to installing and maintain a refrigerated air dryer. Here are some of the aspects to focus on:
Install the air dryer in a cold room that is free of any kind of dirt and dust. You also require a drain to get rid of the water. The standard power requirement for the installation of an air dryer is between 115 and 230 volts.
The most common failure or air dryer breakdown is overheating. When the condenser in the refrigerant circuit catches dirt and dust, or when the room temperature is too high, the dryer fails to get rid of the heat. It, therefore, trips on its over-pressure switch.
You need to clean the condenser once in a while to get rid of the accumulated dirt. In the process, you should take caution because the fins (seen as small plates) are very sensitive and can be damaged easily. The right way to remove the dirt is by using a steel brush to scrape off all the dust gently. You can also buy some special condenser combs to clean and straighten the fins. Cleaning the fins remove dirt and prevents accumulations that would cause overheating of the air dryer.
Another air dryer failure is being too cold. If the compressed air dryer is used to dry air below 0 degrees Celsius, the water removed from the air freezes to form ice particles in the piping. If the problem is not taken care of fast enough, the entire piping system in the air dryer becomes completely blocked.
Sometimes this failure is experienced when the air dryer is set at a very low point, and sometimes it can happen when the refrigerant circuit is experiencing problems. In both cases, you need to repair the air dryer as fast as possible to prevent further damage and complications.
How to Install a Refrigeration Air Dryer
Well, you now know what an air dryer is and how to keep it in shape. The next step would be installing the compressed air dryer in the right to ensure that it operates efficiently. This guide will help you through the process of installing a refrigerated air dryer complete with its filters.
One best practice when installing a refrigerated air dryer is ensuring that you have a multiple feeding into pre-filters with two air dryers. This process will cause a thermal overload in one of the air dryers. For instance, the filters that experience the least pressure drop (one that has the cleanest filter element) will allow more air to pass through. In case the air dryers are not the same brand or model, you may experience different pressure drops. This means that one air dryer will experience higher pressure of compressed air, representing a thermal load, than the other one. The situation can lead to dryers experiencing dewpoint and mechanical instability, causing the air dryer to trip put and compressed air getting wetter. With multiple feeds into the pre-filter, this problem is alleviated.
What is Thermal Load?
In an air compressor, the thermal load is a combination of the following:
- The volume of compressed air as measured in cubic feet per minute (CFM)
- The air pressure entering the compressed air dryer measured in PSI
- The temperature of the compressed air
- The required dewpoint to be achieved by the compressed air dryer.
Compressed air dryers are designed to achieve a specific thermal load. The heat exchanger, condenser, and your air compressor should be set to match the thermal load. The air tools should be designed to handle the required airflow, temperature, and dewpoint. You also need to know that various regions have different set standards for these three elements, and you need to check your location’s set rules.
The Causes of Thermal Overload
The following are possible causes of thermal overload.
- Too much flow of compressed air through the air dryer
- Too high ambient temperatures, or inadequate cooling of air or water in the condenser coil
- Too high inlet temperatures.
If the thermal overload is ignored, the following problems can be experienced.
- Air compressor will experience high-pressure trip outs and venting of gas through the compressor safety valves (if the compressor is fitted with safety valves).
- The air compressor motor will win or fail
- Air compressor internal thermal overload can lead to a constant cut (activation and cutting out) on the air compressor.
- The air compressor will be prone to seizures caused by the compressor oil migration to other components of the circuit.
The Correct Way to Install A Compressed Air Dryer
Below is a systematic representation of how to install an air dryer properly. All the faults discussed above will lead to water being in the bottom part of the air dryer and high dew point. These are the reasons why you need to have an air dryer installed correctly.
Air Filter Installations
Like compressed air dryers, air compressor filters should also be installed in the right manner. Failure to do this can lead to a shortened life span of the air compressor and an increase in the cost of maintenance. It is impossible to dire t equal flow of compressed air through multiple inline filters.
The filter element with the lowest pressure drop leads to the most airflow through it. This, in turn, may lead to premature failure of filter elements and other parts of your air compressor. When filter elements fail, there would be no filtration of compressed air, and that means your airlines will be polluted. On the other hand, sock failure may lead to particulates by projected downstream into the compressed air dryer system. Once this happens, your compressor will experience lower system pressure due to the slowed flow of air through the air dryer.
You should note that the flow of air happens from the core to the outside in a coalescing air filter.
Any compressed air dryer should be installed with a bypass airline to make maintenance easy, quick, and effective. If you are worried about unskilled operators opening the bypass, you can remove the handles or have a double block valve system installed. In such a situation, the mini valve is not exposed to pressure. A bypass system is an essential component that your air dryer should not be installed without it in any way.
Compressor air dryer installation is not as complicated as many people would think. However, the process requires that you understand the basics of an air compressor dryer. If you know what a compressed air dryer is, especially the refrigerated type, and how it works, you will find the installation process quite manageable.
The best way of learning all this is by going through your user manual, which in most cases will have an air compressor installation diagram and instructions. If you follow the description diligently, you will have your air-drying system installed correctly for efficiency is providing dry, compressed air for your applications.