·
Both are measure the amount of water or moisture
present in the air.
Humidity:
·
Is also called absolute humidity.
·
Actual amount of water vapor (moisture) in the
air.
·
Humidity depend upon the atmosphere of the area.
· It is the measure of water (moister) vapor in
the air regardless of temperature.
· Ex : gram of moisture(water) present in cubic
meter of air.
Related Humidity:
·
Also measure the water (moisture) vapor but relative to the temperature.
·
It is important to control the humidity.
·
It is measure percentage of moisture(water) Or
Ratio of the water vapor density.
·
Important factor that affects Quality of
Products.
RH =
actual vapor density
|
/ Saturation vapor density X 100 %
|
= 10.21g/m3 /
25.0g/m3 X
|
100 % = 41%
|
10.210C
at 250C
RH =
actual vapor density (absolute Humidity)
/ Saturation vapor density (dew point) X 100 %
·
Higher related humidity if the air is cooler
·
Lower related humidity if the air is warmer.
When the temperature is low and the relative
humidity is high ( evaporation of water is slow) When the temperature is high
and the relative humidity is low
When relative humidity approaches 100 percent ,
condensation can occur on surfaces, leading to problem with mold, corrosion, decay
and and other moisture related deterioration.
Mold growing = contamination of
the clean area
Corrosion = rust
Decay = break down the component part
Related humidity levels to be maintained using
humidifies, dehumidifiers and and associated control
system.
Measurements – Hygrometer RH –depend upon two
bulbs
1.
Dry bulb temperature
2.
Wet bulb temperature
220
C - 60C = 160C (actual temperature)
