Arkansas HVACR NewsMagazine May 2021

HVACR NewsMagazine May 2021

Tech News

The DOT rating looks different. One common rating you'll see is "DOT- 4BA400." The DOT stands for the U.S. Department of Transportation, which enforces tank manufacturing and testing protocols. The 400 represents 400 PSI, which is the tank's rated pressure. Tanks are always tested to withstand double those pressure conditions (in this case, 800 PSI), but it's a foolish idea to push your luck. The DOT value lets you know how much pressure your tank can withstand before something catastrophic happens (namely, explosions). Needless to say, it would be in your best interest to be mindful of these values.

Know what those stamped numbers mean

You may have noticed that recovery tanks have three numbers stamped on them, typically on the rim or near the tank's top. You will see TW, WC, and DOT on the tank, and each one is critical to your safety. TW stands for tare weight, and it represents the weight of the empty tank. This value is important because you must subtract this number from a scale reading to figure out how much refrigerant you put in the tank. Your scale could read 36.8, but 17 of those pounds could be attributed to the tank weight. There's a pretty big difference between 36.8 and 19.8 pounds of refrigerant, so make sure you're always accounting for the tare weight when you use a scale. WC stands for water capacity, representing the amount of water required to fill the tank to 100% capacity. However, it's worth noting that we do NOT use water as a refrigerant, and we should NEVER fill our tanks to 100% capacity. So, what purpose does this value serve? We'll cover that in detail later, but water is simply a good comparison that we can use to convert the refrigerants' specific gravities.

A scale is your best friend

I know what you might be thinking; scales can hurt our feelings. The scale in my bathroom has hurt my feelings more than a few times, so I wouldn't exactly call that scale a friend of mine. All joking aside, keeping a scale on your truck will help you stay safe during the recovery process. Make sure you bring it out every single time you'll be recovering or charging refrigerant. Weigh the charge each time, even if you feel