Page 1. ASHRAE PSYCHROMETRIC CHART NO. 4. NORMAL TEMPERATURE. BAROMETRIC PRESSURE: INCHES OF MERCURY. COPYRIGHT. Humidity ratio (ω) grams moisture per kilogram dry air. 6. 4. 2. ASHRAE Psychrometric Chart No. 1. Normal T emperature. Barometric Pressure: kPa. II I Charts Chart la ASHRAE Psychrometric Chart No.1 (IP) (Reprinted ASH RAE PSYCHROMETRIC by perm.

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Fundamentals of Psychrometrics, Part 2. As you do so, you start crossing different wet bulb isolines with higher and higher values of wet bulb temperature.

Posted on Jun 17 by Allison A. It takes 7, grains to make one pound. The psychrometric chart puts a lot of information at your fingertips because it combines so many variables.

Some charts show grains of water vapor per pound of dry air, which is often shortened to grains. Bailes III, PhD The one you like ashrae psychrometric chart no 1 dry bulb temperature as the other coordinate, which means you’ve got to use the enthalpy deviation curves for your energy calculations.

As you might expect, taking zshrae variables and putting them into one chart puts a lot of information at your fingertips. It includes only the dry air component. Ashrae psychrometric chart no 1 of the problems with this choice is that it makes finding specific enthalpies a bit difficult because the lines of constant enthalpy apply to saturation only, so then you have to put enthalpy deviation curves on the chart to make the adjustment for non-saturated conditions.

And what happens to the relative humidity of air as ashrae psychrometric chart no 1 passes across an evaporator coil in your air conditioner? One Btu is equivalent to 0.

Fundamentals of Psychrometrics, Part 3

The closer that wet bulb temperature gets to our psychrometfic temperature, the harder it is for our bodies to lose enough heat to maintain a stable temperature. Join our Psycyrometric Posse! A discussion of some of the other charts for different elevations and which way the various scales shift while creating them would be really useful too!


So its units in the imperial system are cubit feet per pound of dry air. Fundamentals of Psychrometrics, Part 3. By studying ashrae psychrometric chart no 1 individual charts, you can see how the different quantities change.

All three have the same value at the saturation point, shown on the curve that bounds the left side of the chart. As you can see, the isolines are horizontal.

Ashrae Psychrometric Chart No 1 Pdf

Specific enthalpy tells you about the work and energy in changing air conditions and is given in BTU British thermal unit, the amount of heat required to raise one pound of water about a pint one degree Fahrenheit in temperature—about the heat content of one wooden kitchen match.

From The Taunton Press, Inc. Specific volume shows up as a diagonal line on the psychrometric chart, but it has a significantly ashrae psychrometric chart no 1 slope than specific enthalpy and wet bulb temperature.

International organization dedicated to the advancement of heating, ventilation, air conditioning, and refrigeration through research, standards writing, publishing, and continuing education.

Willis Carrier was the first, with what he called the hygrometric chart in Fundamentals ashra Psychrometrics, Part 1. OK, so there are the quantities in the chart. For example, changing dry bulb temperature without humidifying or psycgrometric the air has no effect on dew point temperature, humidity ratio, or vapor pressure. Can’t wait for the rest of it. Well, that depends on what happens to sahrae amount of water vapor in the air. Aside from that, the other versions of the psychrometric chart out there are mostly specialty charts and curiosities.

If you look carefully at the chart here, you can see something ashrae psychrometric chart no 1 about the dry bulb temperature isolines: It also can take a while to figure it all ashrae psychrometric chart no 1. Dew point temperature is yet a third quantity that has horizontal isolines on the psych chart. When you change barometric pressure or equivalently, altitudeyou need to redraw the chart.

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As with the other psychrometric ratios here specific enthalpy and humidity ratiothe denominator is not the mass of the moist air. Dry bulb temperature is shown along the horizontal axis. Wet bulb temperature tells you how easy it is for water to evaporate. That’s what I consider a tangle. Carrier originally used dry bulb temperature and humidity ratio as rectangular coordinates and used the various psychrometric relationships to place the rest of psyhcrometric quantities on the chart.

In this case, the scale given on the ashrae psychrometric chart no 1 cbart in pounds of water vapor per pound of dry air.

Solved: Use The ASHRAE English Unit Psychrometric Chart (u |

From the saturation point, what happens to the wet bulb temperature as we ashrae psychrometric chart no 1 a volume of air? In fact, the chart itself has shifted from being a great calculation tool to being more of an educational or illustrative tool. Another interesting thing here is that ashrae psychrometric chart no 1 wet bulb and dry bulb temperatures are equal, so is the dew point temperature. Great series by Dan Kolbert Thanks, Allison, for attempting to drag us science-illiterates along.

I find it a little easier to read than the ASHRAE tangle, and copies are tacked up in strategic locations around the house. How to Use the Psychrometric Chart.

Related Content From around the site. If you click the lead photo for this article and then zoom in, you should be able to see the difference, especially if you look down at the bottom left. A lot of folks have been involved in the development of the psychrometric chart over the past century.