Thermo Scientific MIRAN 205B Series Instruction Manual page 85

Humidity to Absorbance Correction
Correction for humidity may be necessary as water vapor is a strong absorber in the
infrared, with frequently overlapping absorption bands of many compounds of interest.
The relationship between humidity level and absorption is often nonlinear. Humidity to
Absorbance Correction specifies the coefficient for a P, Q, and R parameter, any of
which may be assigned to Range 1, 2, or 3 for each wave for the application. The last
wavelength absorbance for each range configured for a wave is shown on the display. To
accept this data, press
Temperature Compensation Display. To change absorbance values, press
Wavelength Range Select Display appears (see Wavelength Range Select Display,
below)
┌────────────────────────────────────────┐
│╒═HUMIDITY ABSORB->H20══╕Select
││
││
││
││Range 1: -> 0.5000AU
││Range 2: -> 0.7500AU
││Range 3: ---
│└───────────────────────┘
└────────────────────────────────────────┘
Select the desired range (1, 2, or 3). The Parameter Select Display appears (see
Parameter Select Display, below).
┌────────────────────────────────────────┐
│╒═HUMIDITY ABSORB->H20══╕Select
││
││Range 1:4.8%
││
││
││
││
│└───────────────────────┘4=Absorb range │
└────────────────────────────────────────┘
Select the desired parameter (P, Q, R, or Absorb range). The Parameter Enter Display
appears. Key in the desired parameter coefficient (in the form 1.123456E-07) and press
.
ENTER
Note: Use the down arrow key for a minus sign.
If the entry is valid, the display indicates that the entry is ACCEPTED and then changes
to the next parameter to be configured.
Water absorbance at the analytical wavelengths is a percentage of the absorbance at the
water wavelengths. A general relationship for all analytical wavelengths is defined in
Appendix D. The appropriate values are used for each analytical wavelength.
. When the last wave is reached, the display goes to the
ENTER
: 12.345um
Wavelength Range Select Display
Q= 0.000000E-00
P=-7.890234E-01
R= 0.000000E+00
Parameter Select Display
7-31
Chapter 7 Configuration and Setup
│
│wave H2O range:│
│ │
│ │
│ │
│ 1=Range 1 │
│ 2=Range 2 │
3=Range 3 │
│
│wave H2O parms:│
│ │
│ │
│ 1=Q │
│ 2=P │
│ 3=R │
. The
1