Automatic temperature control

Scales win always perform better in a temperature-controlled environment this is particularly important for high precision balances. Those designed to automatically recaHbrate as conditions change will perform better in less-than-ideal conditions. 

Figure 13.34 illustrates a likely location for such a heater. To prevent condensation of moisture they are recommended to reach a temperature rise of only 5-10°C above the ambient temperature, inside the housing and are controlled automatically through a pre-set thermostat. 

A small change in reboiler duty can be approximated by adding the increased traffic to S, and S . If the top temperature is automatically controlled, extra reflux would also result. 

Louvers are probably the most common type of temperature control device on aerial coolers. They may be either automatically adjusted by sensing the process temperature or manually adju.sled. Blade pitch is probably second most common, and variable speed drive is third. 

Rheological and processability behaviors were studied in a Monsanto processability tester (MPT), which is an automatic high-pressure capillary viscometer. The entire barrel and capillary are electrically heated with a microprocessor-based temperature controller [14], The... 

Shutters may be made automatically responsive to air temperature, thus automatically controlling percentage of air pre-cooled. 

Figure 10-191. Temperature control and horsepower savings with automatic variable pitch fans. (Used by permission Hudson Products Corporation.)...

Temperature Control (Manual) (Automatic). Instruments Controls (Weather Protected) (Explosion ProoO Level Controls - To Be Pressure Gauges To Be Condenser Cooling Water ... 

If the instrument is equipped with a manual temperature control, take the temperature of the solutions and set the control to this value if automatic control is available, then place the temperature probe into some of the first... 

Check whether the instrument supplied is equipped for automatic temperature compensation, and, if so, that the temperature probe (resistance thermometer) is available. If it is not so equipped, then the temperature of the solutions to be used must be measured, and the appropriate setting made on the manual temperature control of the instrument. 

The reaction heat is removed by the vacuum evaporation of dilution water. The resulting water vapors allow complete degassing and stripping of any trace of undesired low boiling by products (i.e., 1,4-dioxane for ethoxy sulfates). The product temperature is accurately controlled with the vacuum level kept in the reactor and by the temperature control in the reactor jacket. The automatic control of the different process parameters, i.e., flow rate of reagents, vacuum degree, temperature of thermostatting water, also allows for accurate control of the product concentration. 

Many large air-conditioning plants incorporate automatic control of the humidity and temperature of the issuing air. Temperature control is effected with the aid of a thermocouple or resistance thermometer, and humidity control by means of a thermocouple recording the difference between the wet- and dry-bulb temperatures. 

The concept of an automatic control system is illustrated in Fig. 2.28, based on a temperature-controlled chemical reactor. 

As with condensers, temperature control is not effective, as the saturated vapour temperature is constant at constant pressure. Level control is often used for vaporisers the controller controlling the steam supply to the heating surface, with the liquid feed to the vaporiser on flow control, as shown in Figure 5.20 (see p. 232). An increase in the feed results in an automatic increase in steam to the vaporiser to vaporise the increased flow and maintain the level constant. 

Solutions of 4-nitrotoluene in 93% sulfuric acid decompose very violently if heated to 160°C. This happened on plant-scale when automatic temperature control failed [1], but the temperature was erroneously abstracted as 135°C [2], The explosion temperature of 160°C for the mixture (presumably containing a high proportion of 4-nitrotoluene-2-sulfonic acid) is 22°C lower than that observed for onset of decomposition when 4-nitrotoluene and 93% sulfuric acid are heated at a rate of 100°C/h [3], Mixtures of 4-nitrotoluene with 98% acid or 20% oleum begin to decompose at 180 and 190°C, respectively [3,4], Thereafter, decomposition accelerates (190-224° in 14 min, 224-270 in 1.5 min) until eruption occurs with evolution of much gas [4],... 

Further development of existing machine concepts will come through increased use of electronics (for all basic functions, such as agitation, water level, temperature control, water and suds monitoring, as well as for automatic program modification)... 

Heating and climate control are essential for comfort, and people have always been looking for improvement in this field. In large rooms, such as offices or public buildings (e.g. concert halls), automatic temperature control has become increasingly important. The creation of a comfortable climate is far more complex... 

Measurements of pressure-area (jc-A) isotherms and transfers of monolayers on a substrate were carried out by using a computer-controlled film balance system (San-Esu Keisoku, Co., Fukuoka, FSD-20). Maximum surface area on the trough was 475 X 150 mm2. The trough surface and the moving barrier were coated with Teflon, and the subphase was temperature-controlled with a thermostat (20 0.5 °C). The concentration of lipid solutions was 1 mg/ml and the spreading amount of lipid solutions was 50 - 150 pi. After solvent evaporation, the monolayer was compressed at the speed of 0.60 cm2 s-i. Measurements of n-A isotherms and transfers of monolayer on a QCM substrate were performed automatically with the usual manner [26,27]. 

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