Michell Instruments QMA401, Руководство пользователя

Страница: 54 / 102

QMA401 User’s Manual
44 97450 Issue 2, March 2018
OPERATION
3.10 Calibration Cycle
To maintain the precision of the analyzer, the unit can self calibrate and adjust its
internal reference table based on the result.
This is achieved as follows:
An internal moisture generator uses a permeation tube to generate a nominal moisture
content of 0.5, 5 or 50 ppm
V
, depending on what was specified at the time of order.
The calibration is carried out in a two phase cycle. Initially V1 is energized, causing the
dried sample gas to be routed to the sensor cell for a period of 30 seconds, as shown
by the red line in Figure 27.
SAMPLE
IN
SAMPLE
OUT
DD
HE1 HE2
FC1
V1 V2 V3
MFC
QCH
PS
MG
FC2 FC3
Key
DD
Desiccant column
MG
Moisture generator
MFC
Mass flow controller
V1, V2, V3
Solenoid valves
QCH
Sensor cell
HE1, HE2
Heat exchanger
PS
Pressure sensor
FC1, FC2, FC3
Flow control
Figure 40
Calibration Cycle (Phase 1) - Dried Sample Flow