Sampling manifold

S ample Analysis. The fohowing procedure is used for sample analysis (/) after sample connections are made and the sample tubing purged for 30 minutes, the tubing is connected to the sampling manifold which serves to distribute sample gas to each of the analy2ers, and should analy2ers have specific pressure... 

Sampling errors may occur at the irrlet, and particles may be lost in the sampling manifold while being transported to the collection surface. Figure... 

S. Dcm ribe the precauhons which should be considered when determining the location of tin- sampling manifold inlet for an ambient monitoring system. 

Manifold/instrument Instrument connected to sampling manifold which draws ambient... 

Figure 6-1. In addition to the site description, there is a statement of all the conditions being monitored, the m ods used, and the numerical specifications for the sampling probe, both for the sampling manifold and for the connections from the manifold to the instruments. A third page (not included here) shows a schematic drawing with the dimensions and locations of the bends in the ducting. The sampling-probe specifications currently in effect at four major air pollution control agencies are summarized in Table 6-4.

Another GC method, isotope dilution GC-MS, involves the addition of an isotopomer of the analyte of interest to the sampling manifold (e.g., see Bandy et al., 1993 and Blomquist et al., 1993). In the case of S02, where the ambient S02 consists mainly of K 0 and 32S, S02 containing the 34S isotope is used. This labeled S02 at mass 66 is used as internal standard and has a number of additional advantages such as minimizing the loss of the analyte in the sampling system (Bandy et al., 1993). The air with the added isotopomer is trapped cryogenically and then sampled into a GC-MS for analysis. 

Figure 11.48 is a schematic diagram of this apparatus (Felton et al., 1990). Air is introduced into a sampling manifold consisting of a quartz tube where it is mixed with the l4CO. The air is collected downstream after a measured reaction time and analyzed for l4C02. 

The orifices were then connected into the sampling manifold (Figure 2B). 

Figure 3. System used for calibration of the critical orifices 1, calibrated rotameter 2, 5, vacuum/pressure gauge 3, sampling manifold 4, orifice 6, vacuum pump.

FIGURE 14.5 Sample manifold to transfer C02 from the combustion tube to the reaction tube. (Adapted from Vogel, J.S., Radiocarbon, 34, 344, 1992. With permission.)... 

Figure 19.1 is a block diagram of a typical process analyzer system, consisting of a sample collection and conditioning system, sample manifold, sample inlet, ion source, mass analyzer, detector, and a data analysis and output system that interfaces with the process control system. The dashed line indicates the parts of the overall system that are considered to comprise the analyzer itself (i.e., what is normally included when one purchases a process MS). Figure 19.2 is a photograph of a commercial process MS that incorporates these components. Aspects of these various components are described below, with emphasis on how they are applied in a process mass spectrometer. 

With this method, known as a fast-loop samphng system, the sample is rapidly transported to and from the sample conditioning system, with a small bypass fraction drawn into the sample manifold. 

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