Gas Chromatography
Component separation is achieved using an appropriate packed column, which consists of a suitable length of inert stainless steel tubing packed with particles of porous polymer or bonded phase materials of varying length and diameter (per application). The coating interacts less with smaller and more volatile compounds, causing them to pass more quickly through the column than larger and less volatile compounds.
In some cases, multiple columns may be employed to achieve a quick and thorough speciation of the parameters of interest. An inert carrier gas is used to push the sample through the column at a constant flow rate. With proper temperature and pressure control, the time it takes each gas to exit the column is repeatable. The sample exiting from the column then passes through the detector where the sensor response, during the time a gas of interest is detected, is integrated into a volumetric concentration.
Sample System
The sample system is sealed, insulated and utilizes PID controllers to ensure the ultimate temperature stability of the switching valve and column/detector compartment. Tubing, fittings and components are 300-series stainless steel and teflon. All adjustable pressure and flow devices are easily accessible from the front panel and both the rack and wall-mount configurations provide easy access to the sample system components for maintenance.
The 4060 Series utilizes a switching valve with two states. It starts with the collection of precise volume of the sample while bypassing the carrier gas to the vent. The valve is then actuated to an analysis state where the speciated gas of interest is then pushed through the sample loop by the carrier gas and on to the detector for analysis. The signal peaks are then collected and the gas concentration is measured and displayed.
Detector Technologies
Flame-Ionization Detector (FID)
Due to its high sensitivity to most organic compounds, the flame-ionization detector is a powerful tool for measuring hydrocarbon impurities in gases as well as providing a linear response over a wide range of analysis. Organic compounds from the sample stream or separation column are injected into the detector housing where they are mixed with hydrogen and air before entering the detector jet where the mixture is burned.
During this process, organic compounds are broken down into carbon fragments and acquire a positive charge (i.e., become ionized) at the surface of the anode. Carbon fragments are detected by the collector and the signal is then amplified and sent to the data processing system.
Thermal Conductivity Detector (TCD)
The thermal conductivity detector measures levels of a gas by its ability to conduct heat. The cell block is heated to a fixed temperature that consists of four filaments arranged in a Wheatstone Bridge configuration. Two filaments are exposed to a reference gas (sealed or flowing) of a known thermal conductivity while the other two see the sample gas being measured. A reference voltage is also applied across the bridge.
If the measuring filaments are exposed to a gas of the same thermal conductivity as the reference filaments, the bridge will be balanced (the differential voltage will be zero). However, if the thermal conductivity of the measuring gas changes, the filaments’ temperature will increase or decrease respectively. This change will affect the electrical resistance across filaments, which creates a measurable voltage differential proportional to the volumetric concentration of the gas of interest.
Tracs™ software
Tracs™ software is a unique program used to unveil chromatogram and compound retention sequences on which concentrations of compounds of interest are calculated. It provides valuable access for an ordinary user to look inside the complicated GC world with a computerized tool. It suits the need for high accuracy in GC techniques and for ease of communication in digital formats.
- Bi-directional communication of analyzer’s range, alarm and timing settings which can be remotely uploaded and downloaded
- Acquires real-time raw data for continuous display of chromatogram
- Elution peaks can be displayed within their own respective time frames or individually manipulated for optimal peak scrutinization
- Statistical summary including analytical calculation of measurements, distribution of values and deviations
- Data-logging
- Saving and retrieving of digitized data files
Advantages
- Ease of troubleshooting and root-cause diagnosis
- Faster and more comprehensive factory technical support
- Better analyzer performance monitoring and measurement evaluation
I/O
- 0-1 VDC and 4-20 mADC (isolated) analog outputs
- 0-1 VDC and 4-20 mADC gas identification outputs
- RS-232 duplex digital output
- Two (2) fully-configurable concentration outputs with Form-C relay contacts
- System alarm with Form-C relay contact
- Next Generations will have up to four (8) gas identification outputs, Form-A type
Common Detectable Gases
4060 FID
|
Acetaldehyde
Acetylene
Benzene
Butane
Carbon Dioxide*
Baron Monoxide*
|
Ethane
Ethyl Benzene
Ethylene
Hexane
Methane
MTBE
|
Propane
Propylene
THC
Toluene
VOCs
Xylene
|
*Measurement achieved with methanizer
4060 TCD
|
Argon Impurity
Argon Purity
Carbon Dioxide
Carbon Monoxide
|
Helium
Hydrogen
Hydrogen Sulfide
Krypton
|
Nitrogen Impurity
Nitrogen Purity
Xenon
|
