Refrigerant Cylinder Color

“Hey, grab that Wedge Wood Blue cylinder and let’s go charge this unit. No, that’s the Royal Blue one. There it is, right next to the Medium Blue cylinder. No, that is the Sky Blue cylinder. Gosh, don’t you know your refrigerant colors?”

Back in the good ole days, we just had a few colors to keep up with. Most of us just had to recognize the difference between green, white, and purple.  Now there are so many different shades that not even an interior decorator can keep up with them.

AHRI Guidline N is where the industry normally lists the colors of the different refrigerant cylinders. The latest version lists 46 different colors – the big box of crayons. That is why you should always read the cylinder label, not just go on the color. Guideline N describes four classes of refrigerants and they allow the same color to be used in different refrigerant classes. So it is possible that Sky Blue cylinder could have either R-134a or R-13. The only way you know is to read the label.

PMS 413

In the future you will have an even better reason to read the label – all refrigerant cylinders will be the same color. The 2016 edition of Guideline N specifies that all Refrigerant containers should be painted light green gray (RAL 7044 corresponding with PMS 413) starting in 2020. This is spelled out in section 4.8.

PMS 185

One critical color to recognize is red – PMS 185. Cylinders containing flammable refrigerant should have a red band on the shoulder or top of the container. This is specified in section 4.7. Not only should you read the cylinder label, you should be familiar with the properties of any refrigerant you handle. If you start working with a new refrigerant, you should read the safety data sheet. Most refrigerant manufacturers also have refrigerant properties and handling instructions online. You can download and read the details of Guideline N for yourself  HERE

Keeping Your Cool!

Hot weather is coming, and that can mean slow refrigerant recovery. It is common to have high recovery tank temperatures and pressures shut you down as the temperature rises. The condensing temperature of the refrigerant in the recovery unit has to be higher than the outside temperature, and so the refrigerant leaving the recovery unit can be hot, especially on a hot day. This raises the recovery cylinder temperature and pressure, which in turn makes the pressure leaving the recovery unit climb even higher since it must be higher than the cylinder pressure. You often need to cool the recovery cylinder to keep going. There is the old stand-by: ice and a bucket. It works great, but involves the extra bother of carrying ice and a large bucket to the job site. You can use the recovery machine to cool off the cylinder.

Connect the vapor valve of the cylinder to the inlet of the recovery unit and the liquid valve of the recovery cylinder to the outlet of the recovery cylinder. Purge both hoses of air. Start the recovery unit with both cylinder valves open. After the unit gets started, turn the liquid valve on the recovery cylinder clockwise to create a restriction. Be careful NOT to completely close it off. You have just made a refrigeration system with the refrigerant recovery cylinder acting like a flooded evaporator.

The recovery unit is provides the compressor and condenser, and the partially closed liquid valve on the cylinder acts like a metering device. Liquid in the cylinder boils as vapor leaves, cooling off the remaining liquid. The returning liquid is at a lower pressure and temperature, thanks to heat being removed by the recovery unit and the pressure drop at the liquid valve. It takes a bit of practice to learn where to set the liquid valve, but you can monitor the two pressures on the gauges of the recovery unit. You should see both pressures drop as the unit operates.

I have made cylinders frost on the bottom using this technique. One caveat – if you wait until the high pressure switch on the recovery unit opens, you can’t use this method to cool the cylinder down since the recovery unit won't run at that point. You need to make sure and cool the cylinder before that happens. One manufacturer used to make a recovery unit with this feature built in. You connected two lines from the recovery unit to the cylinder, and anytime you needed to cool the cylinder down you would just set the recovery unit valves to subcool. This kept you from having to move your hose connections after the cylinder was cooled down. However, I don’t think it is available any more.

Short Refrigerant Cylnders

Recently Mr. Simmons, one of our air conditioning instructors at Athens Technical College, noted that a new cylinder of refrigerant felt light compared to the others. A quick check with a scale confirmed his suspicion – the “30 lb” cylinder only weighed 22 lbs including the cylinder and outer cardboard packaging. However, it had never been used. The plastic seal was still intact.  It made me wonder if there were other cylinders that we have used and did not catch. We checked a few others, and it seemed that one cylinder was the only “short” cylinder. Obviously, a cylinder that holds 30 lbs of refrigerant should weigh more than 30 lbs. How much more should it weigh? Generally, the whole package including the box should weigh around 36 lbs. The empty DOT 39 cylinder weighs around 5 lbs and the box weighs approximately 1 lb. I don’t know if our experience is unique, or if it is common for refrigerant cylinders to be short, but I will most certainly be checking from now on. I recommend that you weigh your cylinders before opening the seal to make sure you are getting what you are paying for. A great deal on refrigerant is not a great deal if they don’t actually give you the full amount you are paying for. In our case, I called the company that we purchased the refrigerant from and they quickly replaced the cylinder with a full one. I weighed it to make sure.