Gas chromatographs installing

The addition of a computer to multiple gas-chromatograph installations permitted rapid data analyses and report generation,... 

Gas chromatograph installations range from simple single-chromatograph systems to very complex multibench systems. Concerns for a simple installation also are important for the complex multiple-instrument system. If you plan to design a complex system, you first should read and understand the information presented for the simpler systems, as well as the basic information in the first sections of this chapter. In designing any system, take time to consider your future needs. 

Rotameters In many large-scale gas chromatograph installations, rotameters are used as visual indicators of gas usage. If the rotameter is of the proper size, so that gas use per bench suspends the float or ball midway in the rotameter tube, a quick glance will tell you if you are using the correct amount of gas. Leaks tend to push the float off scale—leaks can easily more than double or more your gas consumption. We recommend one rotameter for the entire lab and one for each bench (Figures 10.31). 

A degasser is installed on the mud line to remove gas from drilling fluid while penetrating gas bearing formations. Samples of gas are analyzed using the gas chromatograph. 

A number of conversion kits are now commercially available that enable any single- or two-oven gas chromatograph to be converted into a multidimensional chromatograph, for example. Figure 8.17 [200,217-219]. To simplify installation all the... 

The GAGI samplers, installed along traverses at both Honerat and Unknown, were left in place for 5 months before being retrieved. Retrieved samplers from both locations were sent to Gore Laboratories where they were heated, and compounds were thermally desorbed and analyzed with a gas chromatograph/mass spectrometer (GC/MS). 

The system used by these workers consisted of a Microtek 220 gas chromatograph and a Perkin-Elmer 403 atomic absorption spectrophotometer. These instruments were connected by means of stainless steel tubing (2mm o.d.) connected from the column outlet of the gas chromatograph to the silica furnace of the a.a.s. (Fig. 13.2). A four-way valve was installed between the carrier gas inlet and the column injection port so that a sample trap could be mounted, and the sample could be swept into the gas chromatographic column by the carrier gas. The recorder (lOmV) was equipped with an electronic integrator to measure the peak areas, and was simultaneously actuated with the sample introduction so that the retention time of each component could be used for identification of peaks. 

GC-Computer System Nowadays, a large number of data-processing-computer-aided instruments for the automatic calculation of various peak parameters, for instance relative retention, composition, peak areas etc., can be conveniently coupled with GC-systems. A commercially available fairly sophisticated computer system of such type are available abundantly that may be capable of undertaking load upto 100 gas-chromatographs with ample data-storage facilities. In fact, the installation such as multi GC-systems in the routine analysis in oil-refineries and bulk pharmaceutical industries, and chemical based industries have tremendously cut-down their operating cost of analysis to a bare minimum. 

Procedure. Install the prepared column into the gas chromatograph but do not connect the column to the detector inlet. Condition the column for at least 4 hours by heating at 302°F (150°C) with the earner gas (helium) flow set at. approximately 50 milli-... 

A gas chromatograph of the Hewlett-Packard 5890 series with a HP 7673A injector and a flame ionisation detector can be used. A capillary free fatty acid phase (Hewlett-Packard FFAP 19091F-105) column (50 m x 0.20 mm x 0.33 pm) is cut into two equal 25-m lengths, which are used for the separation, provided that a capillary pre-column (J W Scientific Altech 93493) with a 50% phenyl silicone DB 17 coating (1.35 m of a 15 mx0.25 mmx0.25 pm column) is installed. 

Multidimensional gas chromatograph with two linked independently operated ovens. The first oven is fitted with an on-column injector, both ovens are fitted with FIDs and the second oven has an olfactometer installed in parallel with the FID. The analytical column is installed in either the FID port or the olfactometer port as described (see Basic Protocol 2). 

Aqueous-phase concentrations of PCE were determined by GC using a Hewlett-Packard (HP) Model 6890 gas chromatograph equipped with an autosampler, a precolumn surfactant trap, an HP-5 crosslinked 5% PH Siloxane column, and a flame ionization detector (FID). The precolumn trap was installed to prevent surfactant fouling of GC inlets, column and detector. Samples were prepared by adding approximately 0.4 mL of aqueous sample to 1.2 mL of isopropanol in glass autosampler vials. The GC vials were sealed with Teflon backed aluminum caps to minimize volatilization. Triplicate injections of each sample were performed. 

Capillary Gas Chromatography (HRGC). Analytical separations were performed on a Varian 3700 GC instrument as well as on a Carlo Erba type 5360 Mega Series gas chromatograph. The Varian 3700 GC system was modified with a hot split/splitless injector and additionally equipped with a commercially available inlet splitter (Gerstel, Mulheim/Ruhr) in order to install two capillary columns... 

Chromatography (See Chromatography, Appendix IIA.) Use a gas chromatograph equipped with a flame-ionization detector. Under typical conditions, the instrument contains a 4mm (id) x 6-ft glass column, or equivalent, packed with 80-/100- or 100-/120-mesh Chromosorb 104, or equivalent. The column is maintained isothermally at about 140°, the injection port at 200°, and the detector at 250°. Nitrogen is the carrier gas, flowing at a rate of about 35 mL/min. Install an oxygen scrubber between the carrier gas line and the column. The column should be conditioned for about 72 h at 250° with 30 to 40 mL/min carrier flow. 

Note Chromosorb 104 is oxygen sensitive. Both new and used columns should be flushed with carrier gas for 30 to 60 min before heating each time they are installed in the gas chromatograph. 

A condenser is then installed and run at the design temperature and pressure. The volumetric flow rates of the feed stream and the vapor and liquid product streams are measured with rotameters (see p. 46), and the MEK mole fractions in the feed and vapor effluent streams are measured with a gas chromatograph. The feed stream flow rate is set to 500 liters/s and enough time is allowed to pass for the product stream rotameter readings to reach steady levels. The feed and product gas flow rates are then converted to molar flow rates using the ideal gas equation of state, and the product liquid flow rate is converted to a molar flow rate using a tabulated MEK density and the molecular weight of MEK. Here are the results. 

A modern-day petroleum refinery is a complex chemical operation that involves numerous separations and chemical processing steps. Today virtually all the chemical analysis equipment found in the research laboratory is also used in the refinery or an online basis is often coupled to a control circuit to monitor product quality and make the necessary immediate adjustment in process conditions required to meet product specifications. While the online gas chromatograph is the most widely used instrument, infrared spectrometers, mass spectrometers, pH indicators, new infrared spectrometers with chemometric capability and moisture analysis based in solid-state conductors are not found in every refinery in the country. Until the 1970s, samples of most process streams in the refinery were taken at periodic intervals during the day and adjustments were made after the research was received from the refinery s analytical lab. This process was followed by the installation of online analysis equipment that sounded alarms, and the equipment operators took appropriate action. Today most operations are on computer control and the information received from online analytical equipment is processed almost continuously and controls make the required changes. An alarm may still sound and the equipment operator still responds, but usually the problem has already been corrected. 

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