空气温度       干空气密度       饱和空气密度 

℃                   kg/m3                kg/m3 

-20                 1.396                  1.395 

-19                 1.394                  1.393 

-18                 1.385                  1.384 

-17                 1.379                  1.378 

-16                 1.374                  1.373  

-15                 1.368                  1.367 

-14                 1.363                  1.362 

-13                 1.358                  1.357 

-12                 1.353                  1.352 

-11                 1.348                  1.347 

-10                 1.342                  1.341 

-9                   1.337                  1.336 

-8                   1.332                  1.331  

-7                   1.327                  1.325 

-6                   1.322                  1.32 

-5                   1.317                  1.315 

-4                   1.312                  1.31 

-3                   1.308                  1.306 

-2                   1.303                  1.301 

-1                   1.298                  1.295 

0                    1.293                  1.29 

1                    1.288                  1.285 

2                    1.284                  1.281 

3                    1.279                  1.275 

4                    1.275                  1.271 

5                    1.27                    1.266 

6                    1.265                  1.261 

7                    1.261                  1.256 

8                    1.256                  1.251 

9                    1.252                  1.247 

10                  1.248                  1.242 

11                  1.243                  1.237 

12                  1.239                  1.232 

13                  1.235                  1.228 

14                  1.23                    1.223 

15                  1.226                  1.218 

16                  1.222                  1.214 

17                  1.217                  1.208 

18                  1.213                  1.204 

19                  1.209                  1.2 

20                  1.205                  1.195 

21                  1.201                  1.19 

22                  1.197                  1.185 

23                  1.193                  1.181 

24                  1.189                  1.176 

25                  1.185                  1.171 

26                  1.181                  1.166 

27                  1.177                  1.161 

28                  1.173                  1.156 

29                   1.169                 1.151 

30                   1.165                 1.146  

31                   1.161                 1.141 

32                   1.157                 1.136 

33                   1.154                 1.131 

34                   1.15                   1.126 

35                   1.146                 1.121 

36                   1.142                 1.116 

37                   1.139                 1.111 

38                   1.135                 1.107 

39                   1.132                 1.102 

40                   1.128                 1.097 

41                   1.124                 1.091 

42                   1.121                 1.086 

43                   1.117                 1.081 

44                   1.114                 1.076 

45                   1.11                   1.07 

46                   1.107                 1.065 

47                   1.103                 1.059 

48                   1.1                     1.054 

49                   1.096                  1.048 

50-54              1.093                  1.043 

55-59              1.076                  1.013 

60-64              1.06                    0.981 

65-69              1.044                  0.946 

70-74              1.029                  0.909 

75-79              1.014                  0.868 

80-84              1                        0.823 

85-89              0.986                  0.773 

90-94              0.973                  0.718 

95-99              0.959                  0.656 

100                 0.947                  0.589 

单位体积空气所具有的质量称为空气的密度，用ρ来表示。即：

                                    （2-1）

式中  ρ——空气的密度，kg/m3；

     M——空气的质量，m；

     V——空气的体积，m3。

一般来说，空气的密度是随温度、湿度和压力的变化而变化的。在标准大气状况下（P＝101325Pa，t＝O℃，＝O%），干空气的密度为1.293 kg/m3。湿空气密度的计算公式为：

               ρ湿＝0.003484（1－0.378）           (2-2)

式中  P——空气的压力，Pa；

      T——热力学温度（T＝273+t），K；

      t ——空气的温度，℃；

     ——相对湿度，%；

     P饱——温度为t（℃）时的饱和水蒸气压力(见表1-9)，pa。

由上式可见，压力越大，温度越低，空气密度越大。当压力和温度一定时，湿空气的密度总是小于干空气的密度。

在矿井通风中，由于通风系统内的空气温度、湿度、压力各有不同，空气的密度也有所变化，但变化范围有限。在研究空气流动规律时，要根据具体情况考虑是否忽略这种变化。

    一般将空气压力为101325Pa，温度为20℃，相对湿度为60%的矿井空气称为标准矿井空气，其密度为1.2kg/m3。