Detector overflow

For nonlinear detectors the calibration curve may be determined by mathematical curve fitting. For complex calibration functions with more than one unknown parameter, additional information (e.g. about the physical theory of the measuring method) or pulse experiments with different concentrations are necessary. In any case, it is advised to check the low and high concentration range by separate experiments with different feed concentrations. There should be no detector overflow at maximum concentration. 

Fig. 8. For XRF measurements with optimal sensitivity a possible detector overflow is automatically recognized, the relevant lines are measured with reduced tube current and the intensities are recalculated...

Automated controls for flocciJating reagents can use a feedforward mode based on feed turbidity and feed volumetric rate, or a feed-back mode incorporating a streaming current detector on the flocculated feed. Attempts to control coagulant addition on the basis of overflow turbidity generally have been less successful. Control for pH has been accomplished by feed-forward modes on the feed pH and by feed-back modes on the basis of clarifier feedwell or external reaction tank pH. Control loops based on measurement of feedwell pH are useful for control in apphcations in which flocculated sohds are internaUy recirculated within the clarifier feedwell. 

The reason is truncation of dynamics in low-resolution modes in a 14-bit-detector each pixel in low-resolution mode can contain 0 to 16382 counts. With the next photon an arithmetic overflow will occur and the pixel is saturated. In high-resolution mode the same area of the detector is represented by 4 pixels, and if the intensity is evenly distributed it takes 4 times longer before the pixels will be saturated. If the high resolution is not required and the cycle time is 30 s or longer, it is good practice to store away the big files on a spacious USB hard-disk and afterwards to bin the data. 

Considerable improvement over film detection can be obtained with either a slow scan CCD camera interfaced to a TEM or with imaging plates. The CCD camera attached to a YAG crystal can have a good linearity in intensity detection, however can present several drawbacks one is the presence of overflow artifacts when ED is recorded, but even more serious problem can be the potential damage of the CCD detector after continuous exposures to high diffracted ED beam intensities. 

In all experiments, gases, liquids, water fraction as well as solid residue were obtained as products and analyzed on different capillary GC columns and registered with TCD-and FID-detectors. The reactor sand used and the fillers in the overflow and cyclone were combusted in a furnace at 810°C to constant weight. The loss in weight was balanced as carbon black. 

Check if there is a waste receiver after the detector. Check injector see if waste receiver is under the overflow. Using an autosampler cormect wash solution if necessary. 

The integral leakage monitoring system will be composed of three parts detection, data processing and monitoring display. Detection will consist of the signals from fire sensors, sodium leak detectors, plant process sensors (sodium flow rate, sodium level in the overflow tank, etc.) and visual information from the TV cameras. 

Fill the Dewar with liquid nitrogen until overflow from the vent tube is observed. The detector itself has a high thermal capacity. It wiU take at least 6h to come to thermal equilibrium. The process of cooling the system from room temperature is discussed in depth in Chapter 12 under thermal cycling . 

Overflow detection may take several forms. It may be automatic, using suitably located gas/ liquid detectors to operate valves or pumps, or it may be manual, relying on operator response to various forms of detection (including alarms raised by suitable instrumentation, visual indications such as direct observation or via CCTV, or smell). The details of overflow detection measures will be site-specific, and a number of factors need to be taken into consideration. 

On sites where hydrocarbon gas or liquid detection is used as a means of overflow detection, the detector type, operation, maintenance and detector location are critical factors. Historically, hydrocarbon detection systems have been found not to be highly reliable because their ability... 

Figure 8.2 (a) The overflowing cylinder (OFC). (b) Schematic setup of the OFC with neutron reflection. Slits - SI, S2, S3, S4. M -incident beam monitor. D - flnal detector. Reprinted with permission from [16]. (2003) American Chemical Society. 

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