By: Fluid-Aire


Winter is upon us again. We all know the summer went too fast, but hey – how can you be better prepared for the cold weather? By learning how cold ambient temperatures affect your compressed air system!

Temperatures below freezing can have many adverse effects on compressed air equipment. The one that is most obvious is that compressed air generates condensate. Condensate will freeze when temperatures drop below freezing. This can cause short-term and long-lasting damage to your equipment such as freezing control lines, freezing and cracking of heat exchangers, frozen drain valves, and much more. Ideally, your air compressor room should not drop below 40 degrees fahrenheit, but in when it does, you need to be aware of the effects that cold ambient conditions can have on your compressed air equipment.


Air Compressors

  • Air compressor oil tends to become thicker when ambient temperatures are cold, thus reducing its lubrication capabilities. Thicker oil also increases the power needed to turn the pump thus increasing motor amp draw and strain on the whole drive train. This can reduce the lifetime of your machine’s motor.
  • Control lines do not operate on the dry side of your compressed air system. Because of this moisture, cold ambient temperatures can lead to freezing up of these lines within the compressor which can quickly alter the operation of the machine.
  • Many rotary screw compressors have low ambient alarms in them, meaning that it will not start if it is too cold.
    Note: if it is already running, it will most likely continue to run because the compressor will generate enough of its own heat to keep it above freezing temperatures.
  • Tip: If your rotary screw air compressor will not start, there is a high likelihood that the ambient temperatures around your air compressor are below +40°F. Many rotary screw air compressors are equipped with a low ambient air temperature limit switch (fault), which does not allow the machine to start below this temperature. See the section below on Tips for getting up and going in cold weather.

Air Dryers

  • In cold ambient conditions, refrigerated air dryers actually tend to operate too efficiently, meaning that the moisture it is trying to separate out will be cooled to a point where it will actually freeze within the machine. This could not only cause internal blockage, but because of the water expanding as it freezes, it will probably also crack the heat exchanger.
  • Also, the drain valve on a refrigerated air dryer may freeze open or shut. This may not create a blockage of the air flowing through the dryer, but it will block the condensate from draining. So even though the dryer is chilling the air, the moisture cannot escape and the dryer becomes ineffective.
  • With desiccant air dryers, wet inlet air can tend to start freezing up inside the piping causing a blockage.
  • Also with desiccant dryers, the discharge air purge mufflers can freeze up, restricting or stopping the purge air flow thus decreasing the drying capacity of the dryer.

Compressed Air Accessories and Other Components

  • As with compressors and dryers, anytime condensate freezes, there is opportunity for air and/or water blockage in all accessories (such as drain valves, filters, and regulators) and receiver tanks. Although thawing of this ice can quickly free up the blockage, freezing water can expand to a point where it will cause permanent damage to the component. Examples: cracked drain valves, fractured filter bowls, and compromised tank pressure ratings.

Tips for getting up and going in cold weather:

  • Shut-off all external fresh outside air sources
  • If it is an enclosed unit, remove or open the doors/panels of the compressor
  • Turn-up or add heat source to the room or area to get the ambient temperatures above + 45°F
  • Once the compressor is warmed up above the set limit (40°F to 45°F), you may need to reset the alarm on the control panel and the compressor should be good to start.
  • Once the compressor is running, inspect closely for leaks.
  • Inspect all condensate drain valves

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