Welch Allyn LC101 CO2 Module - User Manual - Manual (Page 19)

LC101 CO
2
Module OEM Implementation Manual
Welch Allyn OEM Technologies Confidential Page 19
Section 3
LC101 Calibration
The LC101 Module requires periodic user calibration to adjust offset voltages and calibration
constants used by the internal C-Cap bench. There are two types of calibration, each supported
in the LC101 software protocol:
• Zero Calibration
• Two-Point User Calibration
Zero Calibration
The Zero Calibration adjusts the offset voltage used by the C-Cap to generate the CO
2
values
and the IR source current. The required frequency of Zero Calibration depends on the amount
and type of usage, and may be typically required every two weeks. The LC101 does not monitor
the elapsed time between calibrations, nor does it alert the host when calibration is needed. It is
up to the host system and the end-user to determine when calibration is required.
The procedure requires the use of clean, dry air (0% CO
2
) at room/ambient temperature. In
order to provide the 0% CO
2
, an external device, called a “CO
2
scrubber” (or CO
2
absorber), is
used to absorb CO
2
from room air. The scrubber contains a chemical which reacts with and
eliminates CO
2
as it is drawn through the scrubber. The CO
2
scrubber is available from Welch
Allyn OEM Technologies.
The scrubber is designed to be attached directly to the Welch Allyn OEM Technologies watertrap
by the user before a Zero Calibration. The scrubber is removed after successful calibration. The
scrubber has a shelf life of approximately one year. Although the scrubber is considered re-
usable, its effective life depends on application and exposure to CO
2
. The LC101 monitors the
CO
2
concentration in the zero reference gas and will alert the host system, when polled for
status, if a problem exists with the sample zero gas.