Why do level gauges have upper and lower limit markers?

From a safety perspective, it serves as a reminder.

If it’s a float level gauge that isn’t stuck, things might be okay – at least there’s no true vacuum condition. But if it’s a normal ultrasonic level gauge, then it’s completely problematic. The function of giving overestimated or underestimated readings is to alert operators: to check whether the pump will start operating when the tank is empty, whether environmental standards will be violated when the tank is full, whether an explosion in the steam boiler could occur when it’s empty, and whether an explosion in the liquid storage tank might happen when it’s full. My ability to express myself in words is limited, so I can only give you examples like this, haha

As a safety component in chemical processing towers, the upper and lower markers of a level gauge serve to ensure the stable transfer of the medium within the tower. If it is too high, it is not conducive to gas-liquid separation and liquid entrainment is likely to occur. If it is too low, air leakage is likely to occur, posing the risk of high pressure affecting low pressure systems. Therefore, subscripts and superscripts are required to ensure safe operation.

““Upper and lower limit markers”, “draw a red line”, “Why?” The leader said to draw it, so draw it in white. . . Make the drawings better and do your work thoroughly; the leader is training you in drawing. You draw well; maybe you’ll become an artist — that’s probably why

The safety requirements are mainly in place to ensure the safety of operations

Just like the red line on a pressure gauge, it serves a warning purpose from a safety perspective.

High and low limit alarms: the feed pump stops when a high limit alarm is triggered, and the discharge pump stops when a low limit alarm is triggered. Prevent the material inside the tank from overflowing or the feeding pump from operating under no load.

On-site inspections may be more straightforward

The requirements for safe operation are mainly aimed at ensuring operational safety.

That’s the result of experts eating too much and becoming so full that they have nothing else to do, which leads to them harboring malicious intentions. I don’t get it – why is it necessary to include upper and lower limit markers on pressure gauges? These experts treat pressure gauges as if they represented the red line marking 1.8 billion mu of arable land. . . The red lines for the upper and lower limits on the pump outlet pressure gauge – what kind of insane idea is that? . We emphasize every day the need to govern the country according to the law, to act in accordance with regulations, and to follow established standards. Is there a requirement of upper and lower limit lines when selecting a pressure gauge? ? According to textbooks and regulations, the selection of pressure gauges is based on the principle of a usage range of 1/3 to 2/3; then why are upper and lower limit markings provided? Besides, the pressure gauge on-site has an accuracy class of 1.5; its dial markings are not linear but rather discrete. The design pressure for installing the pump results in upper and lower limits of 0.02–2.03. How should the workers paste the red paper? ? ? How many scales on the pressure gauge dial do the width of that red paper cover? How much error does it cover? ? Putting red paper on the pressure gauge to alert the operator – what a joke. . . . If it only leads to misguidance, how can it serve as a reminder? Whether a pump is delivering the required flow rate cannot be determined merely by looking at the pressure gauge at its outlet. The pressure range at the outlet of a pump is not indicated either with red paper. A competent and skilled operator is well aware of the operating performance and parameters of each pump; it’s only those experts who sit in offices all day that have no idea what’s going on on site. Putting red paper on pressure gauges is already annoying; now there are even more weirdos who put red paper on level gauges as well, haha. . . What a bunch of incompetent managers! May I ask, how many of the glass panels, glass tubes, two-color and single-color ones, as well as magnetic ball switches on site are still functional? ? ? There are several glass plate tubes that are dirty and nothing can be seen through them. . . . Red paper is also pasted. When replying on the forum, one netizen said that when encountering problems, one should ask why more often ? So here’s the question. . . Red paper is used on pressure gauges to mark the upper and lower limits. Should red paper be used on motors, pumps, and valves as well? ? Aren’t there also requirements for their speed, their sealing, their switch positions, how many threads are turned, what the speed is, what the level of noise is, and what the level of vibration is? , why not put red paper on it? ? ? Pressure gauges are covered with red paper – why aren’t bimetallic thermometers covered with red paper? ? Is the temperature of pressure vessels not important? ? ?