Thermo 48i - Default Coefficients; Cal Point 1, 2, and 3 Adjust

Calibration
HI and LO Multi-Point Calibration
4-8 Model 48i Instruction Manual Thermo Electron Corporation
The customer defines the ranges and Thermo Electron recommends the
following calibration points for each range:
• Cal Point 1: 80% of range
• Cal Point 2: 50% of range
• Cal Point 3: 20% of range
Default Coefficients Note If performing a multi-point calibration after a “bad” calibration or
changing ranges it is recommended to start off with default values for the
Cal point coefficients. 
To set default values, from the Main Menu select Service Mode > Hi
Multi-Point Cal or Lo Multi-Point Cal. From Hi or Lo Multi-Point Cal,
select Default Coef and press . The instrument will automatically
reset the default values.
Cal Point 1, 2, and 3 Adjust Use the following procedure to adjust cal points 1, 2, and 3.
1. Adjust the zero air flow and the CO flow from the standard CO cylinder
to provide a diluted CO concentration of approximately 80% of the
upper range limit (URL) of the instrument. The total air flow must
exceed the total demand of the instrument connected to the output
manifold to ensure that no ambient air is pulled into the manifold vent.
The exact CO concentration is calculated from:
Where:
[CO]
OUT
= diluted CO concentration at the output manifold, ppm
[CO]
STD
= concentration of the undiluted CO standard, ppm
F
CO
= flow rate of CO standard corrected to 25 °C and 760 mm Hg, LPM
F
D
= flow rate of dilution air corrected to 25 °C and 760 mm Hg, LPM
2. Allow the Model 48i to sample this CO concentration standard until a
stable response is obtained.
)
F
+
F
(
)
F
x
]
[CO (
=
]
[CO
COD
CO
STD
OUT