Specifications

Maxum II Operation Overview, Continued
Refer to Figure 1-4 for the following narrative.
Analyzer Operation
The Power Entry Control Module-Direct Current (PECM-DC), in
response to commands on the internal bus, accepts system primary
power and provides switching and control of AC power for oven heaters
and other AC powered devices.
Power On
Before being piped to the analyzer, the sample from the process is sent
to a sample conditioning system. The sample conditioning system
ensures that the process sample is compatible with the requirements of
the analyzer. That is, it assures that the phase, pressure, temperature
and flow rate to the analyzer are suitable, that the sample is filtered, that
condensates are removed and other treatments are carried out. The
resultant conditioned sample is piped via stainless steel tubing to the
sample valve(s) located at the bottom of the Maxum II Modular Oven.
One sample stream is allowed per oven.
Sample Conditioning
The Sample Shutoff Valve (SSO), mounted in the modular oven, is used
to turn off the sample flow at the appropriate time in the cycle. The
Model 50 valve is used as a sample valve. The Model 50 is a 10-port
valve that is designed for vapor sample only. All valves are controlled by
a Solenoid Valve Control Module located in the electronic enclosure
section of the Maxum II.
Sample Shutoff and
Sample Valves
The Solenoid Valve Control Module (SVCM), which is not shown in
figure 1-4, provides pneumatic on/off control for both sampling and oven
systems functions. Each SVCM consists of a group of solenoids with
control electronics that receives commands from the internal I
2
C bus.
Solenoid commands are received from the Embedded Sensor Near
Electronics (EMSNE) control. Solenoid relay status is read back to the
control software to indicate whether a selected solenoid is to be
deactivated or activated. Timing is controlled by the processor timing.
There is no time base on the SVCM.
Solenoid Valve Control
Module
Commands from the I
2
C bus control the deactivation or activation of
solenoid valves. If fault or warning conditions have occurred, pressure
control and SVCM status information is returned to the database.
The sample is injected by the sample valve(s) into the chromatograph
columns where the sample is separated into individual components.
Many different types of columns may be used and are dependent on the
requirements of the application.
Columns
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