Three Tips for Your Next System Evacuation 

For refrigerant heating and cooling systems to work correctly and optimally, the refrigerant must be free of air, nitrogen, moisture, and contaminants. Therefore, before charging a system, it’s critical to evacuate the system with a vacuum pump to create a clean and sealed environment. Here are a few tips and best practices to make your next evacuation faster and more effective. 


Tip 1: Purge with Nitrogen 

Moisture in a system can drastically increase the time it takes to pull a vacuum and removing that moisture and other contaminants is a crucial step to saving time. To ensure that the system is free of excess oxygen, refrigerant, moisture, and other contaminants, purge it with nitrogen. This is different than flowing nitrogen or conducting a nitrogen pressure test. To purge, connect a nitrogen tank and flow nitrogen through the system at around 100 PSI. This allows nitrogen to flow into one side and then out the other. The movement displaces excess oxygen and air. It also removes any dangerous gases and ensures the system is dry. While performing this purge, be sure to keep the area well-ventilated. Nitrogen can displace oxygen and create a dangerous environment for techs or other occupants, so always keep this in mind. 


Tip 2: Triple Evacuate 

When working in humid environments or on systems with significantly more moisture, a triple evacuation is a great way to remove the moisture entirely. This is an industry requirement for some OEMs, and one of the most effective techniques for systems with high moisture content. Start by sealing the system off and pulling the system down to a vacuum of between 1000 and 2000 microns. Then, break the vacuum by introducing nitrogen for 5 minutes at 5 PSIG. Perform another evacuation to 500 microns, and then break it again with nitrogen for five minutes. Perform a third evacuation and pull the system down to between 200 and 300 microns. Let the system sit for 10 minutes, or longer for larger systems. Performing the triple evacuation purges with nitrogen helps the excess moisture and other contaminants vent out of the system. Not to mention, systems with less moisture allow for pulling a vacuum faster, saving you time on the job. 


Tip 3: Change Your Oil 

Within a system is not the only place where moisture can impede evacuation efficiency. High moisture content in your vacuum pump oil considerably reduces your pump’s ability to pull a deep vacuum quickly. Cloudy oil is a sign of moisture buildup, a natural occurrence in used oil. Vacuum pumps with clean, dry oil can maintain a higher pressure differential, speeding up the vacuum process and allowing for a deeper vacuum. This means more frequent oil changes directly improve your ability to evacuate systems quickly, once again saving you time on the job. With Fieldpiece vacuum pumps featuring the RunQuick® oil change system, you can change oil in seconds without losing vacuum.  

Effective tools are only part of an effective service. Staying informed and up to date on best practice is just as important, so we hope these tips help make your system evacuations easier, faster, and better! 


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