HD32.1
- 11 -
V2.1
Wind Chill (°C)
Frostbite risk
> -28
Low
-28 to -39
Medium: The exposed body parts can freeze within 10 to 30 minutes
-40 to -44
High: The exposed body parts can freeze within 5 to 10 minutes
(*)
Alarm level
-44 to -47
High: The exposed body parts can freeze within 2 to 5 minutes
(*)
-48 and colder
High: The exposed body parts can freeze in less than 2 minutes
(*)
(*)
: With
v
a
higher than 50 km/h the frostbite process can be faster.
In order to calculate the WCI index, the following probes should be connected:
•
The dry bulb temperature probe for air temperature measurement t
a
.
•
The hot-wire probe for wind speed measurement.
In order to measure the WCI index, refer to the following:
•
ISO 7726
•
NOAA Specifications, National Weather Service.
2.1.4 Average Radiation Temperature t
r
The average radiation temperature is defined as the temperature of a thermally uniform simulated
environment that would exchange with a man the same thermal radiation power exchanged in the
real environment.
In order to evaluate the average radiation temperature you have to measure: The globe
thermometer temperature, the air temperature and the wind speed measured near the globe
thermometer.
The average radiation temperature calculation formula is the following:
•
In case of
natural convection:
(
)
(
)
273
10
25
.
0
273
4
/
1
4
/
1
8
4
−
⎥
⎥
⎦
⎤
⎢
⎢
⎣
⎡
−
×
⎟
⎟
⎠
⎞
⎜
⎜
⎝
⎛
−
×
+
+
=
a
g
a
g
g
g
r
t
t
D
t
t
t
t
ε
•
In case of
forced convection:
(
)
(
)
273
10
1
.
1
273
4
/
1
4
.
0
6
.
0
8
4
−
⎥
⎥
⎦
⎤
⎢
⎢
⎣
⎡
−
×
×
×
+
+
=
a
g
g
a
g
r
t
t
D
v
t
t
ε
where:
D
= globe thermometer diameter
ε
g
= 0.95 assumed emissivity of the globe thermometer
t
g
= globe thermometer temperature
t
a
= air temperature.
v
a
= wind speed
The average radiation temperature does not correspond to air temperature: If within a room very
high temperature surfaces are present (for example, a fireplace), these hot areas remarkably
influence the average radiation temperature.
The average radiation temperature is detected with the globe thermometer. A temperature probe
formed by a 150 mm copper ball, painted black matt, with emissivity equal to
ε
g
= 0.95 (according
Summary of Contents for HD32.1
Page 6: ...HD32 1 6 V2 1 Thermal Microclimate HD32 1...
Page 78: ...HD32 1 78 V2 1 MIN 350 MAX 1020 120 AP471 S4...
Page 106: ...HD32 1 106 V2 1 Moderate Environment Norm ISO 7730...
Page 107: ...HD32 1 107 V2 1 Moderate Environment Norm ISO 7730...
Page 108: ...HD32 1 108 V2 1 Moderate Environment Norm ISO 7730...
Page 109: ...HD32 1 109 V2 1 Moderate Environment Norm ISO 7730...
Page 110: ...HD32 1 110 V2 1 Moderate Environment Norm ISO 7730...
Page 111: ...HD32 1 111 V2 1 Moderate Environment Norm ISO 7730...
Page 112: ...HD32 1 112 V2 1 12 2 WARM ENVIRONMENT Norm ISO 7243 Norm ISO 7243...
Page 113: ...HD32 1 113 V2 1 Warm Environment Norm ISO 7243...
Page 114: ...HD32 1 114 V2 1 Warm Environment Norm ISO 7243 Norm ISO 7243...
Page 115: ...HD32 1 115 V2 1 Warm Environment Norm ISO 7243...
Page 116: ...HD32 1 116 V2 1 Warm Environment Norm ISO 7243...
Page 117: ...HD32 1 117 V2 1 Warm Environment Norm ISO 7243...
Page 118: ...HD32 1 118 V2 1 12 3 DISCOMFORT ANALYSIS Norm ISO 7730 Norm ISO 7730...
Page 119: ...HD32 1 119 V2 1 Discomfort Analysis Norm ISO 7730...
Page 120: ...HD32 1 120 V2 1 Discomfort Analysis Norm ISO 7730...
Page 121: ...HD32 1 121 V2 1 Discomfort Analysis Norm ISO 7730...
Page 122: ...HD32 1 122 V2 1 Discomfort Analysis Norm ISO 7730...
Page 123: ...HD32 1 123 V2 1 Discomfort Analysis Norm ISO 7730...
Page 124: ...HD32 1 124 V2 1 Discomfort Analysis Norm ISO 7730...
Page 125: ...HD32 1 125 V2 1 12 4 HOT ENVIRONMENT Norm ISO 7933 Norm ISO 7933...
Page 126: ...HD32 1 126 V2 1 Hot Environment Norm ISO 7933...
Page 127: ...HD32 1 127 V2 1 Hot Environment Norm ISO 7933...
Page 128: ...HD32 1 128 V2 1 Hot Environment Norm ISO 7933...
Page 129: ...HD32 1 129 V2 1 Hot Environment Norm ISO 7933...
Page 130: ...HD32 1 130 V2 1 Hot Environment Norm ISO 7933...
Page 131: ...HD32 1 131 V2 1 Hot Environment Norm ISO 7933...
Page 132: ...HD32 1 132 V2 1 12 5 COLD ENVIRONMENT Norm ISO 11079 Norm ISO 11079...
Page 133: ...HD32 1 133 V2 1 Cold Environment Norm ISO 11079...
Page 134: ...HD32 1 134 V2 1 Cold Environment Norm ISO 11079...
Page 135: ...HD32 1 135 V2 1 Cold Environment Norm ISO 11079...
Page 136: ...HD32 1 136 V2 1 Cold Environment Norm ISO 11079...
Page 137: ...HD32 1 137 V2 1 Cold Environment Norm ISO 11079...
Page 138: ...HD32 1 138 V2 1 Cold Environment Norm ISO 11079...
Page 139: ...HD32 1 139 V2 1 Cold Environment Norm ISO 11079...
Page 140: ...HD32 1 140 V2 1 12 6 PHYSICAL QUANTITIES...
Page 153: ...HD32 1 153 V2 1 NOTES...
Page 154: ...HD32 1 154 V2 1 NOTES...
Page 155: ......