However, there’s one piece of equipment that can have a critical effect on the long term integrity of the platform’s well conductors – conductor centralizers form the interface between the jacket structure and the conductors themselves and have a profound effect on conductor fatigue life. as a thermostat for underfloor heating systems, which switches off the heating pump for safety reasons when temperatures are too high and switches it on again when the temperature falls below a certain level.Installing an offshore platform is a hugely complex, multi-disciplinary operation. Switch contacts can thus perform control tasks, e.g. Such bimetal thermometers can also be equipped with switch contacts which close an electrical circuit when a certain temperature is exceeded or undershot an electrical signal is triggered accordingly.
Figure: Design of a bimetal thermometer (helical type) Figure: Operating principle of a bimetal thermometer (helical type) On a calibrated scale the corresponding temperature can be read off. If the measuring tube is now heated, the helical bimetal winds up and rotates the metal rod. A pointer is attached to the upper end of the metal rod. A rotatable metal rod is guided through this helical coil, which is connected to it at the loose end. The helical bimetal is firmly connected at one end to the inside of a measuring tube (the bimetal is attached to a cylindrical pin, which is pressed firmly into the stem). In these cases, bimetal thermometers are equipped with a bimetal strip wrapped into a helical coil. Figure: Bimetal thermometer (helical type) Figure: Operating principle of a bimetal thermometer (helical type) Or in the food industry it is also necessary to separate the display from the sensor if, for example, the temperature inside the food has to be measured (“piercing thermometer”). The temperature sensor must then be located inside the pipe, while the display for the temperature must be outside the pipe. For example, if the water temperature is to be measured in a heating pipe, as is usual in heating systems. In many cases it is necessary to spatially separate the indicator (pointer) from the sensor (bimetallic coil). Animation: Operating principle of a spiral type bimetal thermometer Helical type bimetallic thermometer Such thermometers are used, for example, in refrigerators or freezers or to determine the room temperature. The entire bimetal thermometer must therefore be located directly in the medium whose temperature is to be measured.
However, the disadvantage is that the dial and the temperature sensor are not separated from each other. Such a design using a bimetallic spiral is not only very space-saving but also cost-effective. Figure: Bimetal thermometer (spiral type) The measured temperature can then be read off a calibrated scale. A pointer is attached to the outer end of the spiral. The inner end of the spiral is firmly connected to the housing. The simplest design of a bimetal thermometer is to wrap the bimetallic strip into a spiral. Figure: Bimetallic strip wrapped into a coil Animation: Bimetallic strip wrapped into a coil Spiral type bimetallic thermometer Depending on whether the bimetallic coil is twisted like a spiral or a screw, two different types can be distinguished. For this reason, a long bimetal strip is often wrapped into a coil. The longer the bimetal, the greater the bend and thus the sensitivity for temperature measurement.
Bimetallic strips can be found in kettles, for example, which switch off the kettle automatically by opening the electric circuit when the temperature is too high (or when the boiling point is reached). Note: Due to the electrical conductivity of the bimetallic strip, it is also frequently used as a safety component for automatic shutdown. In bimetallic strip thermometers the different rates of expansion of metals when heated is used to measure the temperature! Animation: Operating principle of a bimetallic strip thermometerĭue to their metallic materials, bimetallic thermometers can be used at temperatures from below -100 ☌ to more than 500 ☌.īimetal strips are produced by rolling the different metal sheets one on top of the other and then heating them so that the metals bond at the joint by diffusion processes ( cold welding). Figure: Structure and principle of a bimetallic strip The deformation is a measure of the temperature and can be read off a calibrated scale. When heated, the metal strip deforms due to the different degrees of expansion. steel and brass) with different degrees of thermal expansion are firmly joined together. Temperatures can be meassured based on the principle of different thermal expansion of solids. 2.2 Helical type bimetallic thermometer.