Incorrect Temperature

When the temperature of the mixture is too high, the reactions will take place more rapidly. The heat given off by the reaction cannot escape as a 

The size and shape of the article will also affect the temperature required. A sphere may require a lower casting temperature to prevent overheating in the center. 

If the temperatures are too low, the viscosity of the prepolymer will make the mixing of the curative very much harder. The mixed prepolymer also will not flow easily into the mold and will tend to trap air against the mold surface. Another effect is that one can find a roll-type situation with the prepolymer s not joining on itself. 

A mismatch of mold temperature against the prepolymer and the maximum exotherm can cause shrinkage. In a closed mold, internal pressures can cause damage. 

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Temperature is one of the four or five most important parameters in industrial process control and in the chemical industry. Almost all chemical processes and reactions are temperature dependent, and not infrequently in the chemical plant temperature is the only indication of the progress of the process. Where the temperature is critical to the reaction, a considerable loss of product or efficiency may result from operation at incorrect temperatures. In some cases, loss of control of temperature can result in catastrophic plant failure with attendant damage and possible loss of life. 

Short pot life Faster increase in pot viscosity Curative contamination Incorrect temperature... 

High shrinkage Level of material lower than design in molds and vents Incorrect temperatures of mold and polyurethane High exotherm Wrong ratios System contaminated... 

Cheesy appearance Often MDI systems Low green strength Insufficient cure Off ratio Poor mixing Incorrect temperatures... 

There Is only one reported vaporization study for Be()l) Baur and Brunner (926 -1283 K, 2). This study was not considered in the analysis as it had an incorrect temperature dependence, as was also noted by Hultgren et al. (3). 

Look in the thermometer periscope, turn the small knob at the lower right of the periscope base, and adjust the periscope to find the top of the mercury thread in the thermometer. Read the temperature. Wait for the oil bath to cool if the temperature is fewer than 20 Celsius degrees below the approximate melting point of your compound. You ll have to wait for a room temperature reading if you have no idea what the melting point is. You don t want to plunge your sample into oil that is so hot it might melt too quickly, or at an incorrect temperature. 

Incorrect Temperatures If a dryer has correct air flow but evaporative capacity is low, the temperatures must be wrong. 

Process air temperature too low Incorrect temperature setting on-controller Controller malfunctioning Process heating elements Thermostat malfunction Voltage differentials Inadequate air flow Hose connections incorrect Inadequate insulation Dryer inadequate for required temperatures Reset for correct temperature Check electrical connections. Replace/repair if needed Check electrical connections Replace/repair if needed Replace or repair Check supply voltage Check/clean filters, check blower rotation and correct, check and repair air flow meter Check connections. Delivery hose should enter hopper at bottom Insulate hopper and hopper inelt air line Replace with high temperature dryer... 

Some Practical Tips if Thermocouples are Showing Incorrect Temperature Readings... 

Startup of an Inactive Loop or Recirculation Loop at an Incorrect Temperature, and Flow Controller Malfunction Causing... 

Besides the pure component parameters, in particular the mixture parameters, for example of a g -model or an equation of state, should be checked carefully prior to process simulation. The procedure is shown in Figure 11.4 for the binary system acetone-cyclohexane, which may be one of the binary key systems of a multicomponent mixture. From the results shown in Figure 11.4, it can be concluded that the VLE behavior of the binary system can be reliably described in the temperature range 0-50 C with the Wilson parameters used. But from the poor -results, it seems that an extrapolation to higher or lower temperature may be dangerous, as already can be seen from the solid-liquid equilibrium (SLE) results of the eutectic system in the temperature range 0 to —lOO C and also from the incorrect temperature dependence of the calculated azeotropic data. 

The problem of high melt temperature can be separated into two categories an original condition and a condition that developed over time. When the problem is an original condition (i.e., it has always been a problem), it is most likely due to an incorrect temperature profile or an inadequate screw design. All polymers require a certain minimum melt temperature for processing. When a barrel zone is set below this point, the shear energy from screw rotation may raise the temperature up to this value. In such cases, it is usually best, from a control standpoint, to place the temperature controller set points at those natural conditions. 

Finally, high melt temperature may result simply from an incorrect temperature profile. Occasionally, one operator will make set point adjustments that are later adjusted by another operator, and so on. After time, the temperature profile in place may not be best for the present combination of material, hardware, and throughput. This is another reason that a regular log should be maintained of all process conditions. It provides the ability to diagnose problems by re-establishing conditions that performed acceptably. 

Heat is required in most pressing operations to enable the fibres to soften and thus stabilise the garment shape. Temperature selection is of utmost importance, as an incorrect temperature setting can cause damage to fibres and yarns. 

During normal operations, checklists and samples are collected as advanced instrumentation monitors the process. The types of problems a fired heater or furnace system typically encounter include flame impingement on tubes, coke buildup inside the tubes, hot spots inside the furnace, fuel composition changes, burner flameout, control valve failure, and feed-pump failure. Other problems may include incorrect temperature indicator readings, failure of oxygen analyzers, oxygen leaks on the furnace, and the unexpected shutdown of downstream equipment. A fired heater system is designed to run almost continuously, 24 hours a day, 7 days a week. The operational team is in place to ensure that the equipment and systems operate safely, effectively, and produce a quality product that meets or exceeds customer expectations. 

The startup of an inactive RCP at an incorrect temperature is not assessed. Technical Specification 3.4.4 (see Chapter 16 of Reference 5.6) requires all RCPs to be operating during... 

This arrangement allowed very little radiative heating and an assurance that the temperature read by the gas thermometer was very close to the sample temperature. It cannot be emphasized too strongly that an incorrect temperature reading is a serious, even invalidating, error. The temperature needs to be corrected to within 0.01°C, especially if one utilizes any part of the isotherm above 0.3P. ... 

In older texts you might come across a standard state defined for 1 atm (101.325 kPa) in place of 1 bar. That is the old convention. In most cases, data for 1 atm differ only a little from data for 1 bar. You might also come across standard states defined as referring fo 298.15 K. Thai is incorrect temperature is not a part of the definition of standard state, and standard states may refer to any temperature (but it should be specified). Thus, it is possible to speak of the standard state of water vapor at 100 K, 273.15 K, or any other temperature. It is conventional, however, for data to be reported at the so-called conventional temperature of298.15 K (25.00°C), and from now on, unless specified otherwise, all data will be for that temperature. For simplicity, we shall often refer to 298.15 K as 25°C . Finally, a standard state need not be a stable state cuid need not be realizable in practice. Thus, the standard state of water vapor at 25 C is the vapor at 1 bar, but water vapor at that temperature and pressure would immediately condense to Hquid water. 

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