Chromalox Big Red Book
Technical
Reference Data Properties of Air
Specific Heat, Viscosity & Density (Weight) of Air at Various Pressures & Temperatures
Specific Heat (Btu/ Lbs/°F) 0.239 0.239 0.239 0.239 0.239 0.240 0.240 0.240 0.240 0.240 0.240 0.240 0.240 0.240 0.241 0.241 0.241 0.242 0.243 0.244 0.245 0.248 0.25 0.254 0.257 0.259 0.262
Absolute Viscosity (Lbs/ Ft/Hr)
Gauge Pressure in Lbs/In 2 (based on atmospheric pressure of 14.7 Lbs/In 2 absolute at sea level)
Air Temp (°F)
0
10
20
30
40
50
60
70
80 100 120 150 200 250 300
Density (Weight) in Lbs/Ft 3
-20 -10 0
0.039 0.039 0.040 0.040 0.041 0.041 0.042 0.042 0.043 0.044 0.045 0.045 0.046 0.047 0.049 0.051 0.052 0.055 0.058 0.060 0.063 0.067 0.072 0.076 0.080 0.085 0.089
0.0900 0.0882 0.0864 0.0846 0.0828 0.0811 0.0795 0.0780 0.0764 0.0750 0.0736 0.0723 0.0710 0.0686 0.0652 0.0626 0.0603 0.0560 0.0523 0.0491 0.0463 0.0414 0.0376 0.0341 0.0314 0.0295 0.0275
0.152 0.149 0.146 0.143 0.140 0.137 0.134 0.131 0.128 0.126 0.124 0.122 0.120 0.116 0.110 0.105 0.101 0.094 0.088 0.083 0.078 0.067 0.063 0.058 0.053 0.049 0.046
0.213 0.209 0.204 0.199 0.196 0.192 0.188 0.184 0.180 0.177 0.174 0.171 0.168 0.162 0.154 0.148 0.143 0.132 0.124 0.116 0.109 0.098 0.089 0.081 0.071 0.069 0.064
0.274 0.268 0.263 0.257 0.252 0.247 0.242 0.237 0.232 0.228 0.224 0.220 0.215 0.208 0.199 0.191 0.184 0.171 0.159 0.150 0.140 0.126 0.114 0.104 0.096 0.089 0.083
0.336 0.328 0.322 0.315 0.307 0.302 0.295 0.291 0.284 0.279 0.274 0.269 0.264 0.255 0.243 0.234 0.225 0.208 0.195 0.184 0.172 0.154 0.140 0.127 0.117 0.109 0.101
0.397 0.388 0.380 0.372 0.365 0.357 0.350 0.343 0.336 0.330 0.324 0.318 0.312 0.302 0.287 0.275 0.266 0.247 0.230 0.216 0.203 0.182 0.165 0.151 0.139 0.129 0.120
0.458 0.448 0.438 0.429 0.421 0.412 0.404 0.396 0.388 0.381 0.374 0.367 0.360 0.348 0.331 0.318 0.305 0.285 0.265 0.249 0.235 0.210 0.190 0.174 0.160 0.148 0.138
0.519 0.508 0.497 0.486 0.477 0.467 0.458 0.449 0.440 0.432 0.423 0.415 0.408 0.394 0.375 0.361 0.347 0.322 0.301 0.282 0.266 0.238 0.216 0.198 0.181 0.168 0.157
0.580 0.567 0.556 0.543 0.533 0.522 0.511 0.501 0.493 0.482 0.473 0.464 0.455 0.440 0.419 0.403 0.388 0.360 0.336 0.316 0.298 0.266 0.241 0.221 0.203 0.188 0.175
0.702 0.687 0.672 0.658 0.645 0.632 0.619 0.607 0.596 0.584 0.572 0.561 0.551 0.533 0.508 0.488 0.470 0.436 0.407 0.382 0.360 0.322 0.292 0.267 0.246 0.228 0.212
0.825 0.807 0.790 0.774 0.757 0.742 0.727 0.713 0.700 0.686 0.673 0.660 0.648 0.626 0.596 0.573 0.552 0.513 0.478 0.449 0.423 0.379 0.343 0.328 0.314 0.289 0.268
1.010 0.989 0.968 0.947 0.927 0.908 0.890 0.873 0.856 0.839 0.824 0.809 0.794 0.767 0.730 0.701 0.674 0.627 0.585 0.549 0.517 0.463 0.419 0.383 0.353 0.327 0.304
1.318 1.288 1.260 1.233 1.208 1.184 1.161 1.139 1.116 1.095 1.074 1.054 1.035 1.001 0.953 0.914 0.879 0.817 0.762 0.715 0.674 0.604 0.547 0.500 0.460 0.427 0.397
1.625 1.588 1.553 1.520 1.489 1.460 1.431 1.403 1.376 1.350 1.325 1.300 1.276 1.234 1.175 1.128 1.084 1.007 0.940 0.883 0.831 0.746 0.675 0.616 0.568 0.526 0.490
1.934 1.890 1.850 1.810 1.770 1.730 1.705 1.661 1.638 1.604 1.573 1.546 1.517 1.465 1.392 1.337 1.287 1.197 1.118 1.048 0.987 0.885 0.801 0.733 0.675 0.625 0.582
10 20 30 40 50
60 70 80 90 100 120 150 175 200 250 300 350 400 500
600 700 800 900 1000
Water Vapor Content of Air in Pounds of Water/100 Ft 3 at Various Temperatures & Relative Humidity Lbs/100 Ft 3 at Specified Relative Humidity 20% 25% 30% 35% 40% 45% 50% 55% 60% 65% 70% 75% 80% 85% 90% 95% 100%
Calculation of Density at Other Tem- peratures & Pressures Density at a specific pressure and tempera- ture can be converted to density at another pressure and temperature using the following equation: D 2 = D 1 T 1 x P 2 T 2 P 1 Where: T 1 = (°F + 460°) initial condition T 2 = (°F + 460°) new condition D 1 = density lbs/ft 3 initial condition D 2 = density lbs/ft 3 new condition P 1 = absolute pressure (psia) initial condition P 2 = absolute pressure (psia) new condition Calculation of Flow or Volume The same formula can be used to convert air flow or volume at gauge pressure (psig) to standard conditions (atmospheric pressure at 70°F) by substituting cubic feet (ft 3 ) or cubic feet per minute (CFM) for density (D): Std. CFM = Actual CFM (70 + 460) x (psig + 14.7) (T 2 +460) 14.7 psia
Air (°F) -20 -10 0 10
.001 .001 .001 .002 .004 .006 .008 .012 .017 .020 .022 .023 .024 .025 .025 .026 .027 .030 .032 .037 .043 .049 .057
.001 .001 .002 .003 .005 .007 .010 .015 .021 .025 .027 .029 .030 .031 .032 .033 .034 .037 .040 .046 .053 .062 .071
.001 .001 .002 .003 .005 .008 .012 .018 .025 .029 .032 .035 .036 .037 .038 .039 .041 .044 .047 .055 .064 .074 .036
.001 .001 .002 .004 .006 .010 .014 .021 .029 .034 .038 .040 .042 .043 .044 .046 .047 .052 .055 .064 .075 .086 .100
.001 .002 .003 .004 .007 .011 .016 .024 .033 .039 .043 .046 .048 .049 .051 .052 .054 .059 .063 .074 .085 .099 .114
.002 .002 .003 .005 .008 .013 .018 .027 .037 .044 .049 .052 .054 .055 .057 .059 .061 .067 .071 .083 .096 .111 .128
.002 .002 .004 .006 .009 .014 .021 .030 .042 .049 .054 .058 .060 .062 .064 .066 .068 .074 .079 .092 .107 .124 .143
.002 .002 .004 .006 .010 .015 .023 .032 .046 .054 .059 .063 .065 .068 .070 .072 .074 .081 .087 .101 .117 .136 .157
.002 .003 .004 .007 .011 .017 .025 .035 .050 .059 .065 .069 .071 .074 .076 .079 .081 .089 .095 .110 .128 .148 .171
.002 .003 .005 .007 .012 .018 .027 .038 .054 .064 .070 .075 .077 .080 .083 .085 .088 .096 .103 .120 .138 .161 .185
.002 .003 .005 .008 .013 .020 .029 .041 .058 .069 .076 .081 .083 .086 .089 .092 .094 .104 .111 .129 .149 .173 .200
.002 .003 .005 .008 .014 .021 .031 .044 .062 .074 .081 .086 .089 .092 .095 .098 .101 .111 .119 .138 .160 .185 .214
.003 .003 .006 .009 .014 .022 .033 .047 .066 .078 .086 .092 .095 .098 .102 .105 .108 .118 .126 .147 .170 .198 .228
.003 .003 .006 .009 .015 .024 .035 .050 .071 .083 .092 .098 .101 .105 .108 .111 .115 .126 .134 .156 .181 .210 .242
.003 .004 .006 .010 .016 .025 .037 .053 .075 .088 .097 .104 .107 .111 .114 .118 .122 .133 .142 .166 .192 .222 .257
.003 .004 .007 .010 .017 .027 .039 .056 .079 .093 .103 .109 .113 .117 .121 .124 .128 .141 .150 .175 .202 .225 .271
.003 .004 .007 .011 .018 .028 .041 .059 .083 .098 .108 .115 .119 .123 .127 .131 .135 .148 .158 .184 .213 .247 .285
20 30 40 50 60 65 68 70 71 72 73 74 75 78 80 85
90 95 100
Note — To convert “grains of moisture” to pounds, multiply grains by 0.0001428.
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