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How to Recover Refrigerant Quickly and Properly
The way we use and think of refrigerants is evolving quite rapidly. As we shift towards phasing out ozone-depleting refrigerants and considering alternatives, the future of refrigerants may seem a little uncertain to us.
However, one thing is certain. Many HVAC units will continue to rely on the common HCFC, HFC, and HFO refrigerants we use today, so refrigeration recovery as we know it will remain a crucial task in HVAC services for a long time.
We’ve put together a step-by-step process to help you recover refrigerant as efficiently as possible. We also have a few tips for best practices to make your recoveries even better.
1. Remember the basics
As with any potentially hazardous HVAC job, remember to wear appropriate PPE. Don’t show up to a recovery job like you’d show up to the beach. Wear sensible clothing and take other precautionary measures as needed (wear goggles, gloves, and sturdy shoes).
Familiarize yourself with refrigerant recovery safety protocols. You’ll NEVER want to mix refrigerants or fill the tank more than 80%.
Mixing refrigerants is bad for a lot of reasons. Refrigerants have different optimum temperature-pressure conditions, so you’re looking at a decrease in efficiency because you won’t know the exact proportions of each refrigerant or the P-T impacts of mixing.
100% full tanks can lead to hydrostatic pressure buildup, which leads to explosions. Explosions are only cool when nobody gets hurt, and it’s extremely probable that someone will get hurt if you fill a tank improperly—and that someone might be YOU.
2. Remove cores and close core removal tools
You’re going to make your recovery job a lot easier if you remove the Schrader cores before you start recovering the refrigerant. When you leave Schrader cores in, they create a pressure drop and restrict the flow rate during the recovery process. This leads to inefficient recovery and a hotter tank.
Also, keep in mind many large-gauge hoses don’t have core depressors built into them. When that’s the case, you’ll have to remove the cores with a separate core depressor or removal tool.
3. Weigh your tank
We highly recommend taking a scale wherever you take your tanks. That way, you will always be able to determine how much refrigerant is in the tank before starting and how much to add as you go.
You’ll find a few numbers stamped along the top rim of your tank: tare weight (TW) and water capacity (WC). The tare weight is how much the empty tank weighs. Water capacity is the total weight in liquid water required to fill the tank to 100%. Refrigerants have different specific gravities than water, so you’ll have to keep that in mind. Don’t assume that a pound of water and a pound of refrigerant behave in the same way.
Place the tank on the scale and subtract the total weight from the TW. The difference is the amount of refrigerant already in the tank.
If you want to find out the maximum gross weight, then you can use the following equation to determine that (80% refrigerant and the entire tare weight):
0.8 x WC x SG +TW
SG stands for the specific gravity of the refrigerant recovered at a given temperature. AHRI recommends using the specific gravity at 77° Fahrenheit, but we suggest using the maximum temperature your tank will be exposed to. It’s not uncommon for tanks to heat up to 130° Fahrenheit in a van on a hot day in Florida, so we typically use a refrigerant’s specific gravity at 130° Fahrenheit for safety purposes. Eric Kaiser made this table to assist you in determining the appropriate tank fill for 130° Fahrenheit conditions shown below.
4. Don’t use a manifold with a digital recovery machine
Some digital recovery machines don’t require you to use a manifold. Digital recovery machines like the Fieldpiece MR45 and the NAVAC NRDD can have multiple hoses connected at a Wye or T. You don’t need a manifold to connect the High and Low sides due to the digital pressure display. This reduces the possible leak points and hose length. That way, you get more of the refrigerant in the tank rather than in the manifold hoses.
5. Connect hoses to core tools and together at a Wye or T into a full capacity filter drier
Without a manifold, the hoses can connect directly to the core remover tools. Since you don’t have a manifold, you will need to connect those at a Wye or a T junction. From there, you can lead a single hose from that connector to a full capacity filter drier.
We recommend using the largest ¼” flare driers you can find, but these may be difficult to come by. If you can’t find a good ¼” flare drier, we recommend connecting a ⅜” flare drier to a ¼” adapter. We show some pretty long hoses in the picture above, but we suggest using shorter ones if possible. Using a shorter hose reduces the amount of refrigerant in the hoses.
6. Connect out of the drier into the recovery machine inlet and out to the vapor port on the tank
There are two valves on the recovery machine. One leads into the machine, and the other leads out of it. You’ll connect the hose leading from the filter drier into the machine.
The machine’s outlet valve should connect to the vapor port on your tank. The vapor port will usually be between the red and blue knobs on the Y-valve at the top of the tank (as seen in the picture above).
7. Invert the tank on the scale
When you turn the tank upside down, the refrigerant can enter the tank as a liquid without you having to worry about the dip tube resistance.
8. Purge air from the hoses, open the valves, and recover refrigerant
Before you start your recovery, ensure that the hoses don’t have any air trapped in them. Getting air in the tank is not good and can lead to problems later. In the same vein as multiple refrigerants, air is something you do NOT want to put in a tank.
Once your hoses have been purged, follow the manufacturer’s instructions in the manual that came with your recovery machine. Open the valves as they say, and watch the refrigerant flow in (or at least observe the machine doing its job.)
9. Flip the tank upright when only vapor is left and purge the machine
Unless you needed to submerge the tank in an ice bucket, you probably kept it upside down the entire time. When no more liquid flows out of the machine and into the tank, your recovery is likely finished.
That said, it’s always a good idea to purge the machine after each use. Some machines have a knob with “purge” settings on there (like the MR45 shown above), and you can let the machine self-purge by setting the knob to that setting. This setting closes the IN port and allows the machine to create an internal vacuum. You can give your machine a longer life by purging, cleaning, and storing it correctly after each recovery.
Best practices for quality
Pull Deep Vacuum on Tanks
Before using a recovery tank, you should make sure to pull a deep vacuum below 500 microns first. This reduces moisture and non-condensable contamination.
Show integrity in your work
Integrity is a bit vague, and you might wonder how it relates to refrigerants. Being honest and showing good judgment is especially important for reducing contamination risk and managing your tanks well.
Perhaps the best way to show integrity is to label the tanks you’ve filled. Let other people know how much refrigerant you recovered. Your teammates can know exactly what’s in the company’s tanks and who used the tanks for what. Tagging your tanks also makes it easier to keep track of the tanks to send in for recycling.
You can also reduce the risk of cross-contamination by exchanging smaller tanks of valuable refrigerants. When you save up a large tank of R-22, someone else may use the tank and dump some R-22 that has been contaminated with R-410A. That reduces the value of the recyclable refrigerant.
Best practices for speed
Your best practices for speed will directly relate to the equipment you choose to use and how you manage your equipment.
Use large tanks, hoses, and filter driers when possible
“Bigger is better” is generally true for recovery equipment. Larger equipment is beneficial because of higher flow rates/capacity and sometimes durability.
Even though I just said that smaller tanks are best for preventing cross-contamination with expensive refrigerants, there are advantages to using larger tanks. The obvious benefit is that you won’t have to swap out tanks as often during a job. Larger tanks also don’t heat up as quickly as smaller tanks.
Bigger hoses make it easier to pull better vacuums. Whenever possible, use large hoses to recover refrigerant. This will be a general rule for quick, efficient evacuation in general as well. It’s also best to purge your hoses before recovery. For more information on purging hoses, check out this quick article.
Filter driers are crucial for your recovery machine’s well-being. You will want to use large, durable filter driers that can reliably sift the refrigerant into your machine. You can speed up your recovery job and give your recovery machine a longer life if you use large filter driers properly. Be sure to check the filter driers before using them. Dirty filter driers will slow your job down and increase the risk of contamination.
Keep the tank cool
If your tank heats up too quickly, you can run some water over it or place it in an ice bucket. You may also use subcooling or condensing loops.
Subcooling or condensing loops, also known as molecular transformators, cool the refrigerant before it enters the tank. The tank stays cool because you control the temperature and pressure of the refrigerant before it accumulates in the tank.
As you can see, recovering refrigerant is a fairly straightforward process with the proper tools. It also doesn’t take lots of difficult technology or grueling practice to maximize the efficiency of the process.