Continuous sampling

When the operating conditions are uniform and steady (there are no fluctuations in flow rate or in concentration of CO in the gas stream), the continuous sampling method can be used. A sampling probe is placed in the stack at any location, preferably near the center. The sample is extracted at a constant sampling rate. As the gas stream passes through the sampling apparatus, any moisture or carbon dioxide in the sample gas stream is removed. The CO concentration is then measured by a nondispersive infrared analyzer, which gives direct readouts of CO concentrations. 

Figure 25-35 is a schematic of an assembled sampling apparatus used to determine CO concentrations by the continuous sampling method. 

Continuous Sampling Device an air analyzer that measures air quality components continuously. See also monitoring, integrated sampling device. 

Monitoring measurement of air pollution. See also continuous sampling device, integrated sampling device. 

Air monitoring The process of continuous sampling and measuring of the quantity of pollutants present in indoor or outdoor air. 

Continuous sampling The uninterrupted sampling of air or pollutant from a space at a fixed rate. 

In passing we remark that there are well-known statistical methods of hypothesis testing and parameter estimation used in decisionmaking. Sequential analysis is a method of sampling used to decide whether to accept or reject a lot with defective items, or whether to continue sampling. Also, there are various statistical methods used in quality control of a manufacturing process, to decide on how much the quality should be improved to be acceptable. 

The concentration of an oxidative gel breaker can be measured by colorimetric methods, by periodically or continuously sampling the gel [341]. The colorimetric reagent is sensitive to oxidizing agents. It contains iron ions and thiocyanate. Thus the quantity of breaker added to the fracturing fluid can be controlled. 

Economic poisons are probably more closely regulated than any other class of material generally sold. In addition to registration required before a product can be sold, and continuous sampling and investigation after it is once put on the market, each reported case of injury is studied to determine if the material was at fault or if there was misrepresentation made in recommendations for use of the product. Two cases of reported injury that were of particular interest come to mind. 

Thus far it has not been possible to derive from the first principles the coalescence rate function for preferential combination of pellet species of different sizes. Kapur (K4) has proposed an ad hoc rate function in continuous sample space as follows ... 

The reaction manifold describing the automated determination of ammonia is shown in Fig. 6.1. Two alternative modes of sampling are shown discrete and continuous. Discrete 5 ml samples contained in ashed (450 °C) glass vials are sampled from an autosampler (Hook and Tucker model A40-11 1.5 min sam-ple/wash). For high-resolution work in the estuary, the continuous sampling mode is preferred. The indophenol blue complex was measured at 630 nm with a colorimeter and the absorbance recorded on a chart recorder. 

Table 2. Mg Isotopic Composition of Mg-poor Minerals from Allende (continued) Sample 25Mg/2 Mg 26Mg/2ltMg 26Mg (% ) 27Al/21tMg... 

To measure the internal flow velocity in the duct, dust sampling was taken at various points along the vertical diameter. A pitot static tube and magnehelic gauge, shown in Figure 1, was the equipment used for these measurements. The duct humidity, tempertaure, and static pressure were measured to calculate the gas density. In determining the humidity, the wet and dry bulb temperature of a continuous sample stream was used. To prevent dust buildup on the wet bulb thermometer, an inline metal filter was inserted into the line. 

In the second test phase, the application of a new on-line XRF-scanner was tested for 1) continuous till and weathered bedrock samples and 2) till profiles with sampling interval of about 100 m. Continuous samples were taken from the tractor excavated test trenches both from the surface of the pre-Quaternary weathered bedrock and from the till about 0.5 m above the weathered bedrock surface. 

Hollow-stem auger u 180 M,R,I Accurate sampling continuous sampling available diameter limitations fluid levels easily detected no... 

Air-sampling detector Actively and continuously samples the air from a protected space and is able to sense the pre-combustion stages of incipient fire. 

The quality of PW and WFI is constantly monitored. The FDA has provided guidance for the validation of water systems. The validation program consists of three phases. Phases 1 and 2 are for 2-4 weeks each of continuous sampling and testing of water to establish the effectiveness of the pretreatment and purification and distillation processes. Phase 3 is routine monitoring of the water quality over the remainder of a 1 year period to gauge the influences of seasonal conditions on the water quality. 

Zhang, H., and Caprioli, R. M. (1996). Capillary electrophoresis combined with matrix-assisted laser desorption/ionizatlon mass spectrometry continuous sample deposition on a matrix-precoated membrane target. /. Mass Spectrom. 31, 1039—1046. 

Fig. 4. 33 The AKUFVE solvent extraction apparatus Efficient mixing is achieved in the separate mixing vessel, from which the mixture flows down into the continuous liquid flow centrifugal separator (the H-centrifuge, hold-up time <1 s). (From Refs. 83a,b.) The outflow from the centrifuge consists of two pure phases, which pass on-line detectors, AMXs, for on-line detectors or continuous sampling. (From Refs. 80a-80d, 81.)...

Dne to their inherent simplicity, small size, efficiency and speed, the CE and CEC techniques are well suited for adoption as miniaturized process monitoring tools. Efforts have been made for such applications, conpled with continuous sampling from reaction mixtures. The CE lab on a chip has been shown to be a viable tool for real-time quantitation of a reacting system. 

These procedures operate batch-wise. Continuous sample handling has some advantages over discontinuous handling. The samples are not all available at the same time... 

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