Tray, sample

Experiments were conducted in a large (-26 m3) radon/thoron test facility (RTTF) designed for calibration purposes and simulation studies (Bigu, 1984). A number of different materials were exposed in the RTTF to a radon/radon progeny or thoron/thoron progeny atmosphere. Exposure of the materials was carried out under laboratory-controlled conditions of radiation level, aerosol concentration, air moisture content and temperature. The materials used were in the form of circular discs of the same thickness (-0.5 mm) and diameter (-25 mm), and they were placed at different locations on the walls of the RTTF at about 1.6 m above the floor. Other samples were placed on horizontal trays. Samples (discs) of different materials were arranged in sets of 3 to 4 they were placed very close to one another to ensure exposure under identical conditions. Exposure time was at least 24 hours to ensure surface activity equilibrium, or near equilibrium, conditions. 

The sample probe s vertical stroke can be as long as 100 mm and this, with the in built hquid level sensor, allows a wide range of primary tubes and centrifuge tubes to be held on the trays. Sample racks are automatically transported in the front section of the analyser, which in turn simpHfies maintenance should the nozzle become blocked or if mechanical problems arise. The AUSOOO Series provides precise sample dispensing capabihty. Each of the two sample probes aspirates a volume sufficient for a maximum of four chemistries per sample and dispenses it into eight cuvettes on the twin reactor Hnes. The probes are constructed from water-resistant plastic which minimizes any dilution from wash solution or contamination. The built-in level sensor Hmits the immersion of the probe in the sample. The inside and outside of the probe as well as the level sensor are rinsed after each use to further prevent contamination. 

The same increase in 137Cs relative to 54Mn with distance from ground zero is also detected in more distant samples collected at shot time. Figure 15 shows the Cs/Mn ratios for fallout tray samples collected from 5100 to 16,500 feet from ground zero. Air filter sample data and crater lip ejecta samples are also shown for comparison. All data are corrected to T0 or shot time. 

The greatest Cs/Mn ratio observed in the fallout tray samples was 0.1 at 16,500 feet or 10 times that seen in the crater lip ejecta. Air filter samples, on the other hand, exhibited the expected enrichment in the volatile fission product, 137Cs, relative to the highly refractory 54Mn. The relationships of crater ejecta and fallout materials to volatile and refractory nuclear detonation products, shown in Figures 14 and 15, conform to the generally accepted theories on the contrasting behavior of these two radionuclides. 

The analyses for higher alcohols in a set of tray samples in which the primary product was drawn as a sidestream at 186° proof, three trays below the top, are given in Table II. Under the operating conditions for this run, all of the higher alcohols were most concentrated in the lower four trays of the section with an increasing percentage of amyl alcohols on the lower trays. 

This introduces samples, standards, or a wash interval to the analytical system in a preset sequence, and at a controlled rate. An unmeasured volume of specimen is added to a polystyrene cup and placed in the sampler tray. Sampling occurs via a polyethylene catheter connected to the manifold of the analytical system. The catheter dips into the cup at preselected sampling rates, usually 20, 40, or 60 times per hour, and between samples a wash fluid or air is aspirated. Both sampling speed and wash cycle are controlled by a timing cam and can be varied. 

In the use of temperature measurement for control of the separation in a distillation column, repeatability is crucial but accuracy is not. Composition control for the overhead product would be based on a measurement of the temperature on one of the trays in the rectifying section. A target would be provided for this temperature. However, at periodic intervals, a sample of the overhead product is analyzed in the laboratory and the information provided to the process operator. Should this analysis be outside acceptable limits, the operator would adjust the set point for the temperature. This procedure effectively compensates for an inaccurate temperature measurement however, the success of this approach requires good repeatability from the temperature measurement. 

Analysts must recognize the above sensitivity when identifying which measurements are required. For example, atypical use of plant data is to estimate the tray efficiency or HTU of a distillation tower. Certain tray compositions are more important than others in providing an estimate of the efficiency. Unfortunately, sensor placement or sample port location are usually not optimal and, consequently, available measurements are, all too often, of less than optimal use. Uncertainty in the resultant model is not minimized. 

Static sampling systems are defined as those that do not have an active air-moving component, such as the pump, to pull a sample to the collection medium. This type of sampling system has been used for over 100 years. Examples include the lead peroxide candle used to detect the presence of SO2 in the atmosphere and the dust-fall bucket and trays or slides coated with a viscous material used to detect particulate matter. This type of system suffers from inability to quantify the amount of pollutant present over a short period of time, i.e., less than 1 week. The potentially desirable characteristics of a static sampling system have led to further developments in this type of technology to provide quantitative information on pollutant concentrations over a fked period of time. Static sampling systems have been developed for use in the occupational environment and are also used to measure the exposure levels in the general community, e.g., radon gas in residences. 

Sample draw-off connections, usually for liquid from the trays, but some top (overhead) and reboiler vapor as well as liquid can be very useful. 

An application of this instrument is illustrated in the study of color change in dehydrated carrots with storage at different temperatures. Typical results are given in Table IY. The measurements were made on the dry material packed level in a tray designed to fit at a specific level in the instrument. The instrument is mounted so that the tray rests horizontally and no cover glass is then necessary to hold the sample in place. 

In the case of processing study samples, the samples to be processed should be collected fresh and remain fresh (never frozen) in the type of bag, container, etc., normally used for transportation of these crops from the field in commercial practice, e.g., paper bags, net bags, boxes, and trays. This should prevent deterioration of the samples and mimic commercial practices. 

The Benchmate program is started. After unattended operation, the vials are removed from the EasyFill module and placed on the LC/MS/MS autosampler tray for analysis. Each Benchmate Workstation will process up to 50 samples in less than a 24-h period. 

To investigate a vertical distribution of a chemical, a sediment column is divided into sections with appropriate thickness. The sediment column taken in a pipe should be refrigerated in an ice-cooled container, transported to the laboratory, and removed carefully on to a clean tray so that there is as little disturbance as possible to the soil core structure. In the case of a column in which there is little soil moisture and it tends to collapse, the soil should be pushed out to each required thickness and carved off. It is also possible to take a sediment column up to a 30-cm depth using a pipe that is connected to cylinders (5-cm height) with sealing tape. In this case, the sample in each 5-cm fraction can be obtained as it is, after removing the tape. 

Fig. 5.20 shows the instrument with the addition of the ion-selective electrode (ISE) module, which performs Na, K and C02 analyses (240 samples or 720 tests per hour) as requested and without interruption of the other analyses. The sample for electrolyte determination is also placed on the sample tray and a third probe aspirates diluted sample from the reaction tray for processing by the ISE module. Finally, the Technicon SRA-2000 system is a computer-controlled network of the subsystems SMAC II and RA-1000. 

In the determination of metal ions in animal faeces, digestion with 12% perchloric and 56% nitric acids was in progress when an explosion occurred. This was attributed to one of the samples going to dryness on a sand tray heater. 

Process Facilities 15 Area electrical classification 16 Accessibility for mechanical integrity (sampling, maintenance, repairs) 17 Protection of piping and vessels from vehicles and forklifts 18 Protection of small-bore lines, fittings from external impact, personnel 19 Routing of process piping, critical controls cable trays, critical utilities 20 Vent, drain, and relief valve discharge locations... 

Automated online SPE LC systems are used extensively for environmental assays. Trays of SPE cartridges and autosampler can be used in the field. Water samples are preconcentrated trays of SPE cartridges loaded with analytes are brought to the laboratory and mounted onto an online SPE LC/ MS/MS system for analysis. Prospekt and Symbiosis systems were used for monitoring herbicides and transformation products (Hogenboom et al. 1998,1999a and b Lopez-Roldan et al. 2004 Kato et al. 2003 Lacorte and Barcelo 1995 Ferrer and Barcelo 1999,2001 Riediker et al. 2002), phenols... 

To predict the composition, a density meter is installed beside the column. Samples from the feed, distillate, bottoms, and trays 2, 4, 6, 8, 10, and 12 are sent to this density meter through a sampling pump. The samples can be selected from different points by the use of several valves available on the sampling lines. In order to make this sampling continuous, a Taylor Control Language program has been written in... 

Aliquots (0.3-0.5g) of dry sediment (passing 100 mesh) were weighed and then transferred into 10cm3 Coors alumina crucibles. The uncovered crucibles, contained in a suitable tray, were placed into a warm muffle furnace and ignited at 550°C. The samples were maintained at 550°C for 1.5h, then removed, allowed to cool, and transferred into 100ml calibrated flasks 50ml of 1.0M hydrochloric acid were then added to the flasks. The mixtures were next shaken for 14-18h at about 22°C. 

Transfer the soil sample to a suitable metal tray to form a thin layer and, as far as possible, remove any stones present. With very heavy soils it is necessary to break any clods between the fingers. Dry the soil by placing the tray in a current of air at a temperature not exceeding 30°C. With large numbers of samples it is convenient to place the trays on a series of metal racks over which air may be blown from thermostatically controlled fan heaters. Continue the process until the soil feels quite dry. If the soil appears to contain moisture after grinding, return it to the drying rack. 

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