User Manual SERVOPRO PLASMA Trace N
2
Analyzer
APPENDIX 7
86
AUTOMATIC CALIBRATION OPTION
NOTE TO THE READER:
Before proceeding with this section you must first have read and understood the User Manual. Furthermore the analyzer
must be properly started-up. Good calibration depends on hardware used in sampling system.
1) Gas Circuit Description
Analyzers with this option are equipped with 3 solenoid valves. These valves are made of stainless steel and have excellent
characteristics for inboard contamination. These valves are used to select between sample, zero and span gas. All gas
connections are made on the analyzer rear panel. All gas inlets are protected with a 2 micron frit mounted inside the bulkhead.
These are acting as particle filters. Please see the gas flow path drawing on page 6.
When the analyzer is “ON”, there is always one and only one valve, over the gang of three, being “ON”. So the gas flows through
this valve to the common outlet manifold and then to the bulkhead labeled “Trap In”. At the same time, the manifold also
supplies gas to the two other unselected valves and the gas exits the valves through the purge port, to a common header, this one
being connected to the bulkhead labeled “Purge Vent”. Purging the valves this way ensures that there is no unswept dead leg that
would bring contamination of the sample and even eliminates the effect (contamination) of an eventual leaking valve. So, as soon
as the analyzer is “ON”, the three valves are swept by the selected gas and there is a flow going to the “Purge Vent” bulkhead.
The amount of this flow is as the following table:
Inlet Gas Pressure Purge Gas Flow
34 kPa (5 PSIG) 40 ml min
-1
(40 cc/min)
69 kPa (10 PSIG) 125 ml min
-1
(125 cc/min)
We recommend keeping the inlet pressure between 34 kPa (5 PSIG) to 69 kPa (10 PSIG).
2) System Operation
Calibration of the analyzer may be done manually or automatically at a time interval defined by the user. In both cases calibration
gases are selected with SOV1, SOV2 and SOV3. This section explains how to execute a calibration manually and automatically.
NOTE: Zero and span gas values must be set prior to any calibration with a span value bigger than the zero value.
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