Selection issues for temperature and level instruments
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When measuring temperature, integrated temperature transmitters with on-site LED displays already enable on-site indication and control in the control room; then why is it necessary to use a bimetallic thermometer as well? When measuring liquid levels, a magnetic level gauge (with a transmitter) allows for on-site display and remote control; then why is it necessary to use another level gauge with on-site display as well? Can the bimetallic thermometer and the locally displayed level gauge be omitted?
If you want to save money, you can do that, but why was it designed that way in the first place? It is because multiple measurement points are used during the measurement, which allows for comparison and makes it more intuitive. If you use only one method of measurement, for example, a magnetic flap level gauge with reed switches to determine the liquid level, then if the float in that gauge gets damaged, won’t you be unable to see the liquid level? On the other hand, if you have a double-flange differential pressure transmitter, you can still monitor the liquid level. In practical applications, multi-point measurement is used in many cases. It is to ensure the accuracy of the data.
The post isn’t closed, so you can continue: The most basic devices are often the most reliable, especially on-site level gauges. Thermometers are installed at the site, but since it’s not possible to replace them without shutting down operations, they are essentially just for show; most of them are not reliable. Fortunately, infrared thermometers are now available.
The instruments on site can serve as a reference for the transmitter
In terms of function, instruments are classified into local instruments and remote transmission instruments! Due to their complex structure, remote-mounted instruments are prone to inaccurate measurements caused by external factors (such as power supply failures, cable damage, incomplete display, or damaged transduction units). In such cases, it is essential to have access to the local instrument in order to quickly determine where the problem lies! So this is essential from a safety perspective! Moreover, when measuring pressure, nearby measurement points are usually used instead of a three-way valve!
Two are selected as a reference for each other: those on-site facilitate observation by inspection staff, while the remotely transmitted meters enable operators in the control room to carry out process operations!