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Dissolved Gas Analyzer (DGA) GC System - SRI Instruments
DGA GC System
8-9
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For measuring gases dissolved in water, seawater, wastewater, oil, and other liquids.
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HID, FID and/or TCD Detectors
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Built-in PeakSimple Data System
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Built-in Standards Preparation Module
Make Your
Own Standards
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10-port Gas Sampling Valve
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Gas Extraction Loop
...on the compact
chassis
The DGA GC System from SRI is designed to make dissolved gas analysis easier ands less expensive than other
methods. No sample preparation is necessary prior to injection into the DGA GC; this helps to avoid contamination
made possible by transferring the sample between various containers. The DGA GC may also be used online. For
example, you could place the sample inlet tube directly into the ocean and analyze the dissolved gases in seawater.
In the SRI DGA GC, the sample is injected by peristaltic pump through a unique gas extraction loop. The gas extraction
loop consists of permeation tubing encapsulated in a trap-heated glass tube. The permeation tubing is plumbed to
the sample inlet, the 10-port gas sampling valve and the waste/sample outlet.
When the sample is pumped through the gas extraction loop, the dissolved gases permeate through the membrane into
the extraction chamber. Solenoid valves are included for purging the gas extraction loop with helium between runs.
By reconnecting a few tubing lines, the DGA GC can be configured to prepare
dissolved gas standards. A Tedlar bag, or other container, filled with gas
standard of a known concentration is connected to the standard pump. The
standards preparation vessel is filled with sample liquid, such as sea water or
waste water. The standard pump bubbles gas standard into the standards
preparation vessel, equilibrating the liquid over time to the known concentration.
Equlibration takes about one hour.
Solubility of Gases in Water at 1%:
Hydrogen 0.016ppm
Oxygen 0.43ppm
To obtain these chromatograms, the DGA GC