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In chemical companies, the level of liquid ammonia in spherical tanks is measured using differential pressure transmitters. Over the years of use, these transmitters have shown significant measurement errors and are difficult to maintain; the measurement errors become even greater when liquid ammonia is added to the tanks. Later, another set of magnetic flap on-site indicators was added, but the liquid level indicated by the transmitter never matched the liquid level shown by the on-site indicators. Later, external level gauges were used in the technical upgrades; these gauges require no drilling or welding for installation, offer accurate measurements, are easy to install, and provide excellent performance. https://bbs.hcbbs.com/forum.php?mod=image&aid=2419557&size=300x300&key=d471a05a26784254&nocache=yes&type=fixnone Working principle of external-mounted level gauges: External-mounted level gauges require holes to be made in the tank wall; they do not need flanges, and there is no need for welding or cleaning of the tank. They do not come into contact with the liquid or gases inside the tank, allowing for easy online installation and maintenance. They represent a completely non-contact, isolated type of instrument. https://bbs.hcbbs.com/forum.php?mod=image&aid=2419559&size=300x300&key=9a6552957e826564&nocache=yes&type=fixnone Key features of external-mounted level gauges. The ELL-FI adaptive external-mounted level gauge enables continuous and accurate measurement of the liquid level inside a tank from outside the tank, without any contact with the liquid or gases inside, thus achieving true isolated measurement. Automatic calibration is provided, enabling a \"plug-and-play\" installation and use. 1. Safety: When measuring toxic, corrosive, pressurized, flammable, explosive, volatile, or leak-prone liquids, since both the measuring probe and the instrument are located outside the container, there is no contact with the liquids and gases inside the tank during installation, repair, or maintenance, making it very safe. Even when the instrument is damaged or under maintenance, there is absolutely no possibility of leakage. (1) It can be used in various harsh environments. (2) Liquids of any pressure can be measured. (3) It can measure the most corrosive liquids. (4) Liquids with highly toxic properties that can be measured. (5) It can measure flammable, explosive, leak-prone, and polluting liquids. 2. Durable: The measuring head and instruments have no mechanical moving parts and are tightly sealed. It does not wear out or corrode, is highly reliable and durable, and requires little maintenance. 3. Easy to install and maintain: It is the most convenient and cost-effective for installation and maintenance. No holes need to be made in the container, no flanges or connecting pipes are required, allowing for easy installation on both new and existing containers. https://bbs.hcbbs.com/forum.php?mod=image&aid=2419558&size=300x300&key=fccd23b156d476b8&nocache=yes&type=fixnone4. Automatic calibration – no manual calibration is required during installation or use. It’s very convenient, and it maintains high precision permanently. Since the ELL-FI adaptive external-mounted level gauge measures the liquid level from outside the container, without requiring any drilling or welding, it is extremely safe and reliable to use, and its installation is very simple. Therefore, it is particularly suitable for measuring liquid levels in the following situations: (1) various pressure vessels. (2) Flammable and explosive liquid levels. (3) Volatile and leak-prone liquid levels. (4) There are corrosive and toxic liquids. (5) Clean containers free from microbial contamination. Points to note for the maintenance of external-mounted level gauges: 1. The level sensing element is a very sensitive part, so care must be taken when handling it to avoid damage. Do not remove the installed level gauge if no maintenance personnel designated by the manufacturer are present. The instrument cannot operate stably and properly, usually because the level sensor has not been installed correctly. Therefore, the area where the sensor head is installed on the container wall must be smooth and flat. 2. The appearance of E-0 and E-1 codes indicates that the instrument’s self-check failed; restart it. 3. The appearance of the E-2 code indicates an error in the parameter settings; the parameters should be reset. 4. If it resets automatically frequently after startup, it indicates that the circuit board or the level sensor is damaged, and the components need to be replaced. 5. After the gauge is turned on or reset, a moving short bar is displayed continuously, indicating that the gauge does not detect a liquid level signal or that the signal is too weak; this may be due to poor contact with the outer wall of the container or poor cable connection. Performance of external-mounted level gauges: Since we began using external-mounted level gauges for measuring the liquid ammonia level, these gauges have operated with great accuracy. Compared to 1151 transmitters and magnetic flap level gauges, they exhibit low error rates, stable performance, and no faults at all; they are thus ideal instruments for measuring the level in ammonia storage tanks. The instrument features a 5-digit LCD display at the site, as well as a 4–20 mA DC current isolated output that can be sent to a DCS for display, or to the control room for display on other secondary instruments.