Thermocouple placement

Where applicable, thermocouple placement shall be in the container cold zone, as determined from generated container mapping studies. 

Copies of all penetration distribution and challenge thermocouple placement diagrams... 

The high-pressure inlet is attached to a f in. cross to provide ports for gas introduction, pressure measurement, and thermocouple placement just in front of the frit. The Bourdon gauge (0-10 bar) should be connected via a tee to a purge valve to facilitate gas changes. Before use the assembly should be tested at 10 bar for leaks. Thermal insulation such as glass wool should be wrapped around the frit assembly to keep the expansion as adiabatic as possible. 

Figure 3 Thermocouple placement for the shelf temperature distribution studies.

Fig. 3. Representation of a two heat-flux calorimeter showing (a) Boersma thermocouple placement and (b) the Tian-Calvet design. The schematic diagram (c) is appropriate for analysis of the response of both types of calorimeters. Symbols in (c) are subscript T refers to temperature, R refers to reference the temperatures of the block, sample, container, reference, and reference containers given by Tb, Tsc, T-r, Trq, respectively capital R refers to heat transfer resistance in the instrument (9).

Figure 9 shows several TPD spectra of mass 31 (P) at different exposure times to calcium phosphate solution (55). Phosphorus desorption from alumina riiows broad features from 450-700 K, the residual salt peak at 980 K, and a high tenq>erature feature, vAach occurs between 1400 and 1560 K. Variation in the tenq>erature associated with the high tenq)erature desorption feature may be a result of variations in heating rate or thermocouple placement. Unlike the titania spectra, the large feature at 1200 K is absent. In addition, at least one new feature can be observed at approximately 450-700 K Figure 9b shows the corre onding calcium and potassium desorption features. The ratio of calcium and potassium ions to pho horus is conq)arable, but for longer exposures, this ratio decreases dramatically. For a 30 hr. e q>osure, the calcium and potassium to phosphorus ratios drop to less than 1% of the solution concentration. Integration of several phosphorus desorption ectra provide the data for an adsorption isotherm shown in Figure 8. Onset of rapid uptake of pho hate is observed between 20-25 hr.

The heart of the thermogravimetric analyzer is the thermobalance, which is capable of measuring the sample mass as a function of temperature and time. The relationship between the components of a thermobalance varies from one instrument to another. A schematic representation as shown in Figs. 3.1a and 3.1b indicates typical thermocouple placements relative to the sample. The three standard sample and furnace positions relative to the balance are depicted in Fig. 3.1a. Figure 3.2 shows actual examples of currently available commercial instruments. 

Figure 3.2. Three examples of commercial thermobalances, including typical thermocouple placement (a) a top-loading model (courtesy of Netzsch Instruments) (b) a side loading model (courtesy of Mettler-Toledo) (c) a bottom-loading model (courtesy of TA Instruments).

Figure 1. Thermocouple-placement location of pBGA to CBGA adjacent rework study.

Thermocouple and temperature sensor probe placement within the containers shall be documented. 

Sensors are distributed equally in various areas of the stability chamber no less than 2 inches from any wall. A set of sensors should be placed near or at the temperature and/or humidity controller of the chamber, as the controller will maintain the set-point temperature and/or humidity within the chamber during normal use. For a typical walk-in chamber, a minimum of 24 thermocouples and six resistance-transmitting devices are recommended for use in the mapping study. For a benchtop or reach-in chamber, a reduced number of sensors may be used. It is important to note that regardless of the size of the chamber, the placement pattern of the sensors should be such that any potential hot or cold spots are mapped, particularly those areas near the door and comers of the chamber. Typical sensor placement patterns for a reach-in and walk-in chamber are shown in Figures 16.1 and 16.2, respectively. In these examples, the extremities of the chamber (i.e., top and bottom) have a larger number of sensors than the middle of the chamber, since these areas would have a greater probability of either hot or cold spots, due to the airflow pattern within the stability chamber. 

Figure 3.1 is a schematic of the differential thermal analyzer (DTA) design. The device measures the difference in temperature between a sample and reference which are exposed to the same heating schedule via symmetric placement with respect to the furnace. The reference material is any substance, with about the same thermal mass as the sample, which undergoes no transformations in the temperature range of interest. The temperature difference between sample and reference is measured by a differential thermocouple in which one junction is in contact with the underside of the sample crucible, and the other is in contact with the underside of the reference crucible.1 The sample temperature is measured via the voltage across the appropriate screw terminals (Vt,) and similarly for the reference temperature (Vrr) generally only one or the other is recorded (see section 3.5.1). Sample and reference... 

The use of thermocouples to monitor product temperature inside selected vials with the lyophilizer is still the prevalent practice. The utility of this data is questionable and the current trend is to eliminate this requirement as soon as possible to better assure sterility of the unsealed vials by eliminating placement of the thermocouples. 

Instrumentation will include field instruments used in the manufacturing process and other instruments assoeiated with special tasks, such as that of monitoring laboratory or computer room environmental eonditions. The accessibility of instruments must be such as to permit their eleaning and maintenanee. Siting is also important, and instruments should be installed as close to the point of measurement as possible. The placement of flowmeters in piping dead-legs should be avoided. Careful consideration should also be given to the appropriate position of other instruments sueh as thermometers and thermocouples so that they, too, can fulfill their measurement and eontrol functions. Construction materials that come into direct contact with the pharmaceutical or healthcare production process stream must not contaminate or affect the manufactured product in any way. Instrument lubricants and coolants must not come into contact with in-process product or equipment. The reliability of instruments should also be considered for instance, a pressure transmitter that uses atmospheric pressure as its reference may suffer from poor reliability. A draft calibration schedule may also be prepared. 

FIGURE 16.21 Preparation of thermocouple wires (a) wire placement for gas and arc welding of base metal thermocouples, (b) wire placement for arc welding of all standardized thermocouples, and (c) wire placement for resistance welding. 

Placement of several thermocouples along the length of the reactor... 

After placement of the buffer, hydraulic packers and piezometers installed in the rock monitored the hydraulic gradients towards the borehole. Also thermocouple psychrometers were installed within the buffer to measure transient water contents. 

The most common method for reducing the effects of environmental inputs is isolation. Here, each of the measuring elements is effectively isolated from environmental changes. Examples are the placement of reference junction of a thermocouple in a temperature-controlled enclosure rmd the use of active vibration-isolation tables to isolate a measuring system (e.g., atomic force microscope) from external mechanical vibrations. Of course, it is possible to reduce environmental influences by selecting a transducer material that is completely insensitive to a specific environmental parameter. An example is the use of a metal alloy in strain gauges that has a zero coefficient of thermal expansion. But such an ideal material is often difficult to find and quite expensive. 

The materials of the thermocouples — stainless steel yam and constantan wire — are processed onto the mattress topper layer by tailored fibre placement (TFP). TFP is an embroidering technique that is used to stitch fibres and yams that cannot be used as an embroidery yarn on a basic fabric. The reasons of their non-suitability of embroidery can be their thickness, fineness, or stickiness or the material itself. The principle of the TFP method is shown in Figure 9.6. The TFP method is most suitable for large-scale manufacturing. The upper sewing thread primarily serves to fix the thermocouple... 

Thermocouples. In order to obtain some information on the temper atures of the thermal and biological shields, thermocouples will be embedded at 47 points throughout the reactor structure. The locations of these 47 points are given in Table 2.8,A. As a factor of safety, two thermocouples will be attached to the steel or embedded in the concrete at these points. It should be noted that the locations given in Table 2.8.A are recommended best points, but construction difficulties may cause a shift in some of these locations. As built drawings should be consulted for final placement data. It is currently planned to bring out the thermocouple leads in small conduits to Junction boxes on the north and east faces of the reactor structure. 

Heat is usually applied in various amounts and in different locations, whether in a metal plasticating barrel (extrusion, injection molding, etc.) or in a metal mold/die (compression, injection, thermoforming, extrusion, etc.). With barrels a thermocouple is usually embedded in the metal to send a signal to a temperature controller. In turn, it controls the electric power output device regulating the power to the heater bands in different zones of the barrel. The placement of the thermocouple temperature sensor is extremely important. The heat flow in any medium sets up a temperature gradient in that medium, just as the flow of water in a pipe sets up a pressure drop, and the flow of electricity in a wire causes a voltage drop. 

Placement of the thermocouple is critical to accurate temperature measurement. Ideally, having the thermocouple in the sample itself would give the most accurate reading of the sample temperature. 

Shelf temperature distribution verification of the temperature homogeneity across all shelves at one time. The shelf temperature mapping is by use of a large number of thermocouples (in our case, five per shelf each, e.g., 70 thermocouples per measuremeut event), one of the most complex, time-consuming, and error-prone measurements in equipment qualification. It requires an experieneed protoeol executer for eahbration, proper placement... 

Fig. 15. Possible placements of the thermocouple relative to the sample in TGA (Gallagher, in Ref. 5).

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