AN607 Datasheet, PDF (31/41 Pages) Silicon Laboratories – HUMIDITY AND TEMPERATURE SENSOR DESIGNERS GUIDE

APPENDIX C—TERM, UNIT, AND COEFFICIENT
REFERENCE
AN607
Absolute vapor pressure—A measure of the actual amount of water present in the air.
Dew Point—For a given RH and temperature, the temperature at which condensation would form if the air
were cooled; meaningful as an indicator of comfort.
Hydrophobic—Water repellent/resistant.
IP Rating—Ingress Protection Rating; first digit indicates level of protection against particle; the second
digit represents level of protection against liquids.
IP67—An ingress protection rating indicating that the assembly is dust tight (6) and can withstand up to
1 m of water pressure (7).
Kapton—A polyimide film developed by DuPont that is stable over a wide temperature range (up to +400
°C). It is available in sheet, tape, and “dot” form and is used to protect selected components during solder
reflow.
Oleophobic—Oil repellent/resistant.
Relative Humidity—Absolute_Vapor_Pressure ÷ Saturated_Vapor_Pressure; expressed as a percentage.
Saturated vapor pressure—The maximum amount of water that the air can hold; dependent on
temperature.
Table 4. Common Pressure Unit Conversions
Unit Pascal
(Pa)
Pa
1
hPa
100
kPa
1000
bar 100,000
atm 101,325
torr 133.322
psi 6.895 x 10³
*Note: 1 torr ~= 1 mmHg
Divide to Convert
Hectopascal
(hPa)
1x10^–2
1
10
Kilopascal
(kPa)
1x10^–3
1x10^–1
1
Bar
(bar)
1x10^–5
1x10^–3
1x10^–2
Atmosphere
(atm)
Torr*
(torr)
lbf/in²
(psi)
9.8692x10^–6 7.5006 x 10^–3 145.04 x 10^–6
9.8692x10^–4 7.5006 x 10^–1 145.04 x 10^–4
9.8692x10^–3
7.5006
145.04 x 10^–3
1000
100
1
0.98692
750.06
14.50377
1013.25
1.33322
68.95
101.325
1.01325
1
133.322 x 10^–3 1.3332 x 10^–3 1.3158 x 10^–3
6.895
68.948 x 10^–3 68.046 x 10^–3
760
1
51.715
14.696
19.337 x 10^–3
1
Temperature Conversions:
T_°C
=
5_--
9
 T _°F
–
32 
T_°F
=


95_{--}
T_°C
+
32
T_°K = T_°C + 273.15
T_°R = T_°F + 459.69
Rev. 1.7
31