We’ve seen in recent blogs that Compressed Air Dryers are an important part of a compressed air system, to remove water and moisture to prevent condensation further downstream in the system. Moisture laden compressed air can cause issues such as increased wear of moving parts due to lubrication removal, formation of rust in piping and equipment, quality defects in painting processes, and frozen pipes in colder climates. The three main types of dryers are – Refrigerant, Desiccant, and Membrane. For this blog, we will review the basics of the Refrigerant type of dryer.
All atmospheric air that a compressed air system takes in contains water vapor, which is naturally present in the air. At 75°F and 75% relative humidity, 20 gallons of water will enter a typical 25 hp compressor in a 24 hour period of operation. When the the air is compressed, the water becomes concentrated and because the air is heated due to the compression, the water remains in vapor form. Warmer air is able to hold more water vapor, and generally an increase in temperature of 20°F results in a doubling of amount of moisture the air can hold. The problem is that further downstream in the system, the air cools, and the vapor begins to condense into water droplets. To avoid this issue, a dryer is used.
Refrigerant Type dryers cool the air to remove the condensed moisture and then the air is reheated and discharged. When the air leaves the compressor aftercooler and moisture separator (which removes the initial condensed moisture) the air is typically saturated, meaning it cannot hold anymore water vapor. Any further cooling of the air will cause the moisture to condense and drop out. The Refrigerant drying process is to cool the air to 35-40°F and then remove the condensed moisture. The air is then reheated via an air to air heat exchanger (which utilizes the heat of the incoming compressed air) and then discharged. The dewpoint of the air is 35-40°F which is sufficient for most general industrial plant air applications. As long as the compressed air stays above the 35-40°F temperature, no further condensation will occur.
The typical advantages of Refrigerated Dryers are-
– Low initial capital cost
– Relatively low operating cost
– Low maintenance costs
If you have questions about getting the most from your compressed air system, or would like to talk about any EXAIR Intelligent Compressed Air® Product, feel free to contact EXAIR and myself or one of our Application Engineers can help you determine the best solution.
Fog. Nobody likes driving in it. It’s downright perilous to sailing vessels on the open water, but especially those near the shore, or other watercraft. Flights get delayed or cancelled, stranding travelers in airport terminals far from home, and keeping many from pressing matters that necessitated the speed of an airline flight in the first place. Oh, and it’s ALWAYS where the bad guy is hiding in the movies. You can tell by the ominous low-string music that starts playing right before things get real nefarious.
You know who LIKES fog, though? Greenhouse operators. Their plants get plenty of water to sustain their growth from the well-irrigated soil, but the leaves & petals can wither and get discolored if the humidity isn’t kept at a high level.
The same is true for the parts of a greenhouse that folks don’t see when they’re selecting the annuals to plant on the next nice spring weekend (which we should be coming up on quite soon here!) – like the seed germination chambers. I had the pleasure of helping a greenhouse operator recently, who needed to replace some old, and malfunctioning, nozzles in one of their germination chambers. They were interested in the extremely fine mist that our Atomizing Spray Nozzles produce. After some experimentation with a couple of different flow rates & patterns, they determined that the Model AW1020SS (Wide Angle Round Pattern, Internal Mix) Atomizing Spray Nozzles provided optimal results.
As the fogging systems in their other chambers start to fail, they’ve been replacing them with the AW1020SS’. We shipped them two earlier this week.
Recently, I was working with a customer that has purchased several of the EXAIR Atomizing Spray Nozzles, specifically the model Aw5020SS. The customer had another project coming up and needed two more nozzles. I inquired about the application and we discussed at length the way the nozzles are being used.
When a concrete road is being poured, several sample forms are poured during the process. The local Department of Transportation takes the samples and cures them in a wet room for 30 days, and then performs tensile testing, to confirm the concrete meets the strength requirements. The wet room must be kept at 23°C (73.4°F) and 100% Humidity during this time frame. The EXAIR model AW5020SS Atomizing Nozzles are used to provide the moisture that ensures the room humidity conditions are met and maintained. Because the droplets are very fine, the effect of a fog is achieved, with the water droplets suspended in the air, keeping the humidity at 100%.
Atomizing spray nozzles are capable of producing very fine droplet sizes. A typical rain drop is 6000 microns in diameter, standard liquid nozzles produce droplets ranging from 300-4000 microns. The EXAIR Atomizing Nozzles produce droplets from 20-100 microns!
Droplet sizes can be adjusted by varying either the liquid pressure or air pressure. Increasing the air or decreasing the liquid pressure will generally produce a smaller droplet size.
EXAIR manufactures (3) types of Atomizing Nozzles – Internal Mix, External Mix, and Siphon Fed, in both 1/4 NPT and 1/2 NPT sizes. Maximum liquid viscosity is 800 cP. Flow rates range from 0.6 GPH up to 303 GPH, so we’ll be able to find one that meets your flow requirements.
To discuss your application and how an EXAIR Atomizing Nozzle can benefit your process, feel free to contact EXAIR and myself or one of our other Application Engineers can help you determine the best solution.
The ETC Dual Cabinet Cooler Systems work in conjunction with EXAIR’s UL listed Cabinet Cooler Systems which provide cooling for your electrical enclosures without the use of refrigerant based coolants or fans. The Cabinet Cooler Systems utilize a compressed air driven Vortex Tube which uses compressed air. This cold compressed air is exhausted into the enclosure which results in a cool working environment for your electronics. Warm air from inside the enclosure is vented safely back out of the cabinet through built in exhausts and the compressed air is only utilized when the internal air temperature reaches the digitally set temperature on the ETC.
Another added benefit of the ETC on the Cabinet Cooler system is the real time readout of the internal air temperature of your enclosures. This is on top of the push button set point which will give you a +/-2°F ambient temperature inside of your enclosure.
The ETC Dual Cabinet Cooler Systems are designed for larger heat loads ranging from 3,400 BTU/hr. to 5,600 BTU/hr. The units are available in NEMA 12, NEMA 4, and NEMA 4X ratings. This means whether you are in a fairly clean environment or a dirty, hot, muggy environment, EXAIR has you covered.
EXAIR Cabinet Cooler Systems are able to cool your electrical panels using only clean, dry compressed air. Other systems such as cooling fans or heat exchangers use ambient air full of dust and humidity. The temperature of ambient air also fluctuates with the seasons and will be very warm in the summer months, which degrades their ability to cool as the temperature rises. One of the myths about compressed air cooling is that humidity from the compressed air source will enter the cabinet. A water/dirt filter separator will prevent condensate from entering the cabinet and since relative humidity is carried away with the hot air exhaust, relative humidity will stabilize to 45%. This video shows how quickly EXAIR’s Cabinet Cooler Systems will have an effect on relative humidity.
As the weather in the Northern Hemisphere changes over from winter to spring and temperatures start to climb, it is slowly becoming necessary for customers to utilize the Cabinet Cooler Systems to keep control panels cool.
One such situation involved a customer who was building a panel for his client in Malaysia. Malaysia is about 3 degrees north of the Equator, so it is what I would call a semi-tropical if not tropical environment. And such places are quite high in humidity levels. This customer had a client who was in the palm oil processing industry which is quite big in Malaysia. He needed a Cabinet Cooler System to generate about 1000 Btu/hr. of cooling power in a NEMA 12 type system. So I recommended he go with a 1700 Btu/hr. Cabinet Cooler System so he had plenty of capacity. I also recommended he go with 24 VDC thermostat control so he could easily pull the power out from within his panel and not have to run any new circuits.
As the customer duly noted, the fact that the Cabinet Cooler System purges the cabinet with clean, cool and dry compressed air allows for the humidity levels to hang down at a much lower level around 40 – 50% RH instead of up around 80 – 90%. This is attributed to the processing and drying of the compressed air at the production point before it is sent out to the facility and again at the point of use with the included, 5 micron, compressed air filter/separator that comes with each system.
Previously, the customer was using only the small, DC type fans to pull that hot, humid air through the panel which led to many corrosion issues and did not relieve the heat issue at all. With this new improvement, the end user no longer has to worry about such issues. Also, there is virtually no maintenance for this system which produces much longer up-times for the customer as there are no moving parts to wear out. Overall, it was a good recommendation in this case as the Cabinet Cooler System was handling multiple, previously negative issues. Now the pain has been taken away and the end user can move on to solving other, more pressing problems.
Often times, an end user or OEM will contact EXAIR for help with Cabinet Coolers. Most often the need comes from an installed cabinet experiencing overheating conditions. But, there are a large number of applications seeking EXAIR Cabinet Coolers on the front end, before installation or even construction of the enclosure.
For example, an end user of our product overseas needed to cool a single circuit board to ensure continuous operation. Keeping the device cool and dry in an open environment would have proved difficult due to high local humidity. So, an enclosure was constructed and an EXAIR Cabinet Cooler was used to not only regulate the air temperature, but also the stabilize relative humidity within the enclosure to 45%.
Another international end user sent me a number of schematics for a new installation. The proposed enclosure is already in use in other locations, but is experiencing high rates of failure due to high levels of ambient dust. Using the Cabinet Cooler Sizing Guide we were able to determine heat load and the proper Cabinet Cooler model number. A benefit beyond the cooling capacity of a Cabinet Cooler system, is the ability to place a positive purge on the enclosure. This purge is helpful in non-hazardous, dusty and dirty environments. The positive air flow into the enclosure prevents dust from entering (of course, any vents or filters will need to be sealed).
Whether the environment is humid or dusty, we have a suitable solution to cool an enclosure using EXAIR Cabinet Coolers. Contact an Application Engineer with any questions.