100%
0%
More
Less
Cycle Phase
Ae
rati
on
Decontami
nati
on
Condi
ti
oni
ng
Dehumi
di
fi
cati
on
CONDENSATION POINT
RELATIVE
SATURATION (RS)
RELATIVE HUMIDITY (RH)
VAPORIZED HYDROGEN
PEROXIDE CONCENTRATION
Humidity
H
2
O
2
Concentration
Figure 4 Example behavior of H
2
O
2
concentration, relative saturation (RS), and relative humidity
(RH) in a vaporized H
2
O
2
bio-decontamination cycle (non-condensing conditions)
In the non-condensing bio-decontamination cycle example shown in
:
• In the
dehumidification
phase, RH (and RS) decreases.
• When the
conditioning
phase starts, H
2
O
2
concentration rises rapidly. There is also a rapid
increase in RS, which indicates the humidity caused by both H
2
O
2
vapor and water vapor.
Because the generated H
2
O
2
vapor is typically mixed with water vapor, RH also starts to
rise.
• In the
decontamination
phase, H
2
O
2
concentration is steady. However, RS level rises slowly
close to 100 %RS, i.e. condensation point, due to rising RH level.
• In the
aeration
phase, H
2
O
2
concentration, RS, and RH all decrease. When H
2
O
2
concentration is zero, RS equals RH.
The way your bio-decontamination process is designed affects which parameters you want to
measure in different phases.
Depending on your bio-decontamination process, you may also want to either create or avoid
condensation during the conditioning and decontamination phases. In these phases, the air in
the bio-decontaminated space always contains both water and H
2
O
2
vapor, which both affect
the possibility of condensation. To monitor and control whether and when condensation
forms, it is useful to know the
combined
humidity level of water vapor and H
2
O
2
vapor: relative
saturation (RS). When relative saturation reaches 100 %RS, the vapor mixture starts to
condense.
Chapter 3 – H2O2 Measurement
17