Why should a system be evacuated epa

As you probably already know, refrigerant and oil should be only two substances within a refrigeration piping circuit. Any amount of moisture, air, or a combination of non-condensable gasses in the system can wreak havoc on the proper function of your system. To maintain the integrity of your refrigerant circuit, proper evacuation must take place anytime the system is opened and exposed to outside elements. The EPA states that systems should be evacuated to a minimum of 300 microns, but which tools should you use to ensure that you are pulling a proper vacuum?

The goal of evacuating a system is to reduce the pressure from atmospheric pressure of 14.7 PSI (760,000 microns) to as close to zero as possible. Typically, a standard of at least 300 microns is required.

To accomplish this, you are going to need a tool that will allow you to pull the system into a deep vacuum. This process can only be accomplished if the system is “tight” meaning, free from any leaks. If the system is leaking, you will not be able to pull the system down low enough.

Before starting your evacuation process, test your pump. Do this by connecting a micron gauge directly to your pump and verify that your pump can easily pull down to at least 50 microns. If you are unable to pull below 50, check the connection to ensure that there are no leaks at any fittings ( I like to use a little Nylog). Make sure that the oil is new, and verify that all hose gaskets are in good shape. If you suspect that your micron gauge is faulty try cleaning it with an eyedropper full of denatured alcohol and place a few drops into the gauge port. Allow the alcohol to sit for a few seconds and then gently tip the gauge up and down a few times before dumping out the alcohol. Repeat this process several times to ensure that any oil or anything that may be contaminating your gauge sensor is removed. Retest, and compare to another micron gauge if possible.

I personally prefer the Appion Tez 8 vacuum pump due to the large 1/2” and 3/8'“ ports for maximum flow and the ease/speed of the oil changes. The time savings I have experienced using this pump definitely help justify the cost.

2. Evacuation rated hoses

Don’t use your charging manifold for pulling vacuums. Typically charging manifolds are small diameter (1/4”) and full of additional restrictions such as core depressors. Additionally, most hoses that are on charging manifolds are not rated for use during an evacuation. You can test this by placing your evacuation setup onto your pump and pulling it down as low as it can, if the micron level varies widely from the above test, or the level immediately rises once the pump is isolated, you know that there is a leaking point in your setup. I recommend you pick up a set of evacuation hoses that you only use for pulling a vacuum. We have had great luck with the Appion hoses, and I recommend them to all of our helpers and apprentices. You will thank me later.

The beauty of these hoses are that they are 3/8” female on one side which will connect directly to your pump, 3/8” diameter throughout the entire body of the hose, and have a 1/4” female connection at the opposite end for compatibility with most equipment manufactures. There are no core depressors, and I have found that using these hoses has greatly reduced the evacuation time needed, especially on large tonnage units.

3. Core Removal Tool

You may be wondering at this point, “how does this setup work if there are no core depressors”. This is where the core removal tool comes into play. The goal is to have the least restrictive set up possible in order to effectively speed up your evacuation process. Removing the Shrader cores, along with the depressors in the hoses allows us to do that. I’ve used both Appion and yellow jacket core removal tools, but I only use the Appions for evacuation. I have had two of the yellow jacket tools leak under a vacuum, but that could just be my bad luck.

If you not ever used one of these tools, they work by, pulling back the core removal portion of the tool, and threading the tool onto your 1/4’ Shrader core port. push the remover section back in, towards the Schrader core until you feel it align onto the core. You are now able to un-thread the core, pull the remover section back out of the tool body, close the isolation valve, and remove your core.

This valuable tool allows you to swap out leaking cores without pulling charge, pull cores for evacuation and then reinstall them after you have charged the system. I carry two of these tools in my evacuation kit, one for each connection port. An added benefit of using these tools during your evacuation is that they allow you to completely isolate your tools from the refrigerant system. If you have your micron gauge directly on the system, (which you should) you no longer have to wonder if a rising micron level is due to a leaky hose or if there is still a refrigerant leak.

4. Evacuation Tree

If your Vacuum Pump is like any of the pumps I have used, then the blank-off isolation valve probably leaks. None of the isolation valves built into these pumps seem to hold very well, and they all seem to end up leaking over time. In the case of the Tez 8 pump Pictured above, it doesn’t even come with any type of isolation valve. I’ve been running this yellow jacket evacuation manifold before the Tez 8, back when I was using a JB pump. The benefit of using the evacuation tree is that in addition to gaining a valve that actually holds, you also gain the ability to connect (2) 3/8” evac hoses as well as ( 1 ) 1/4” port. The bottom of the Tree is 1/2” which allows you to connect to the largest port on most vacuum pumps and also includes a 1/2” to 3/8” step down so that you can use it on pumps without the 1/2” port. I’ve seen some people run their micron gauge from the 1/4” port on top of the tree, which is an ok place, but I much prefer to place my micron gauge onto one of the side ports of the Schrader core removal tool as we discussed earlier.

Last but not least is a quality Micron gauge. This is a necessary tool that enables you to determine when you have pulled an adequate vacuum to remove all moisture and gasses from the system.

We have tested multiple micron gauges throughout the years, some were completely unreliable, and leak-prone while others we found were great. Personally, I’d recommend picking up a yellow jacket. Be sure to take care of where you place the gauge to prevent getting oil on the sensor and messing up your readings. Never connect it in a downward slope, this will increase the likenesses of oil contaminating your sensor.

If you do happen to contaminate the sensor, clean it with denatured alcohol as discussed above. If the sensor gets completely ruined, there are replacement sensors available. This can be an expensive piece of gear, but I think that the price is well worth it for peace of mind. Doing the job right the first time its much cheaper than returning on a warranty call.