Thermocouple Location

The sample material curve starts out as a parabola as the outer layers reach the inversion temperature, so much heat is required to change them from the low to the high form that the heat supply is interrupted. The rate of heating at the center of the sample material slows up before the material at the center has reached the inversion temperature. As soon as the rate of heating at the center starts decreasing, the differential temperature curve will start to deviate from its baseline. At this point neither the center of the sample material nor the center of the reference material is at the inversion temperature. Smyth (85i states that not too much importance can be attached to this point of initial deviation. 

When the sample material inversion is completed, the distribution curve comes to a sharp point at its center. Since such a sharp point corresponds to a very high value of the second derivative of the equation 

Curve (a) departs from zero some distance below the 50°C inversion temperature and readies its peak some 20°C above the inversion temperature. In curve b), the sample material surface temperature would correspond to the temperature of the metal block in which the sample and reference cavities are located. This curve starts deviating from the baseline at the inversion temperature, which, if this temperature could be accurately determined, would have useful significance on such a curve. If the differential temperature is plotted against the temperature at the center of the sample material, as shown in curve (c), the peak maximum temperature would be equal to the inversion temperature. 

Smyth (85) illustrated the type of DTA curve obtained if the sample and 

Curve (a) shows the differential temperature curve if the thermocouple is 0.06 cm from the center, instead of at the center, of the sample material. In curve (b), a rather extreme case is presented in which the sample thermocouple is 0.30 cm from the sample center. In both curves, the peak maxima temperatures are completely different from those of the symmetrically centered thermocouples. 

---

The sample is assembled into the permeation cell after first having had its thickness accurately measured, with the sample supported by a stainless steel porous sinter (not visible in the photographs). The test cell is heated to test temperature by suitably controlled band-heaters, test temperature being measured by a thermocouple located close to the sample. Test gases are boosted to test pressure using a gas intensifier operated by pressurized air. 

Fig. 21. Comparison of time-average temperature reading from thermocouples located at different axial points on the periphery of the carbon bed for periodic flow interruption and steady-state operation. Time-average u = 1.65 mm/s for flow interruption, r = 60 min and s = 0.5. Gas and liquid inlet temperature is about 26.5°C. (Figure from Haure et al., 1989, with permission, 1989 American Institute of Chemical Engineers.)...

In a similar method, Ramousse et al. [248] designed a technique wherein the sample material is placed between two copper plates that have thermocouples located at their centers. Copper plates were chosen due to the high thermal conductivity of copper and to ensure a uniform temperature distribution. Fluxmeters to measure the thermal flux between both plates were located beside each copper plate. At each end of fhe apparatus, end plates... 

Aseptic BPS machines are subject to steam-in-place sterilization following standard CIP cycles. The SIP cycles are routinely measured by thermocouples located in fixed positions along the product pathway. Validation of SIP cycles should be carried out to demonstrate that consistent sterilization temperatures are achieved throughout the equipment to prove that the system can be effectively sterilized. Validation should also identify suitable positions for routine use, or justify the fixed probe positions already in place. The SIP validation is generally carried out with the help of additional thermocouples and should include the use of biological indicators (appropriate for moist heat sterilization). Test locations should include areas which may be prone to air or condensate entrapment. An accurate engineering line drawing of the system to aid identification of suitable test locations and document test locations selected should be available. 

Thermocouple locations at which temperatures were measured are Identified In Figure 7. The fourth burn was carried out on the right half of the block, with air as well as some CO2 being injected for about 13 hours. The diameter of the reaction... 

Heat transfer models are a powerful tool for developing autoclave process cycles. They are especially useful in aiding tool designers in choosing tooling materials, thicknesses, and thermocouple locations. Models can also be used to determine if a tooling concept would be detrimental in a specific position in the autoclave and the types of tools that should be processed together to optimize the cure cycle. 

Sterilizer engineering drawings Sterilizer operation procedure Sterilizer sanitization procedure Sterilizer maintenance procedures Sterilizer specification utilization list Distribution thermocouple location diagrams Temperature sensing unit location diagram (continuous sterilizers) Sterilizer process log sheets... 

The cold spots recognized during the temperature investigation (worst case) are investigated again by placing a spore strip near each thermocouple location which has been proved to be a cold spot. Besides, the two spore strips shall be used as a positive control. 

Seven thermocouples will be positioned in different locations of the vessel along with one B. stearothermophilus strip (population 10 ) for microbiological challenge test (for thermocouples location, refer to attached layout). 

If a temperature of 200°C were used and thermocouples located at the coolest area of the load showed that the bottle interior equaled 200°C or greater for 15 min, the Fm value would be at least... 

Do a series of repetitive runs for each sterilization cycle in an empty vessel in order to verify the accuracy and reliability of the sterilizer controls and monitoring equipment. Thermocouple locations should be basically the same for all the heat-distribution studies. 

Mixing was carried out with a stirrer at 2200 rpm and the formulation was rapidly poured into a large mold provided with thermocouples, located at various heights, to monitor the foam-rising process. 

The plotter, records the signal of a chromel-alumel thermocouple located inside the heating furnace near to the sample holder in the x-axis the temperature of the furnace is scanned from 27°C to 1000°C at a rate of 16°C/min. In the y-axis, the rectified output voltage, V0 (0 V [Pg.190]

In method (1) the conductivity or pH is higher after each test and eventually the entire vessel contents have to be renewed. This is not the case in (2). Hoogendoom and Den Hartog (1967) added a small quantity (1-2%) of heated (20-40°C) liquid in their liquid mixtures during homogenization, the temperature was measured with thermocouples located at several positions in the vessels. This yielded quantitative information on the progress of mixing at these locations. 

A conventional pulse catalytic microreactor was used with 15-65 mg of the catalyst for the cumene runs and 65 mg for the 2,3-dimethylbutane runs. The catalyst was held between 2 small plugs of borosilicate glass wool in a 5-mm ID diameter borosilicate reactor. In some experiments, the catalyst was diluted with 96% silica porous glass powder. The helium gas was purified by passage through alumina kept at liquid nitrogen temperature. The reaction temperature was measured by a thermocouple located adjacent to the reactor. The catalyst was pretreated at the desired temperature for 16 hours in a stream of helium. The products were analyzed with a dioctyl phthalate gas chromatography column at llO C. 

Figure 14 Thermocouple locations in LFA filter. (Courtesy of Deut. Keramische Gesellschaft.)...

Of the three sources of stress, namely, mounting, vibrations, and regeneration, the latter two are most critical and are influenced by temperature gradients and physical properties. Figures 19 and 20 show thermocouple locations and the temperature-time history of the center and peripheral regions, defined by... 

Figure 19 Thermocouple locations at the midsection of filter during regeneration. (Courtesy of the Society of Automotive Engineere.)...

---