Arkansas HVACR NewsMagazine May 2026

HVACR NewsMagazine May 2026

Tech News

So, if we focus on a 65°F (18.33°C) dew point on the right side of the chart, you will notice that it crosses over 92 grains (there are 7000 grains of moisture per lb) of moisture line and then goes all the way across until it intersects with the curved 100% humidity line on the left side. That shows us that at a 65°F (18.33°C) dew point, the air always contains 92 grains of moisture per lb. ALWAYS. It also shows us that when the air is at 100% relative humidity, the dew point, wet bulb, and dry bulb temperatures are ALL THE SAME. If we have a dew point of 55°F (12.77°C), the air contains 64 grains of moisture per lb. If the dew

point is 30°F (-1.11°C), the air contains 24 grains… you get the point. So, if you find the dry bulb temperature and the relative humidity now, you can easily calculate the dew point at which that same air will reach saturation and begin to form condensation. Let's say we have 75°F (23.88°C) dry bulb air at 50% relative humidity. We would simply draw a line up from the bottom at 75°F (23.88°C) until we hit the curved 50% line. Then, go right (or left) until you bump into the grains of moisture and then the dew point scale. Now you know at what temperature that same air mass will start to condense water.