Issues with the float in magnetic flap level gauges during winter operation
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I would like to ask fellow sailors: our magnetic flip-type level gauge uses a stainless steel float. It works fine in summer, but in winter the float sinks down (the temperature here in winter ranges from -10 to -25 degrees). After checking, the float appears to be in good condition. The measuring medium is mainly a mixed liquid of methanol and hydrocarbons. The density of the measuring medium is approximately 0.72 g/cm3, while the density of the float is 0.62–0.6872 g/cm3. When the liquid is drained into a bucket, the float can also float. I would like to know what causes the float to sink I hope all fellow sailors can provide their valuable opinions!
I’m not sure if the liquid in question, as mentioned by the original poster, experiences temperature fluctuations throughout the year (Especially the temperature of the liquid inside the magnetic flap.) I assume that in winter, when the temperature is low, the liquid inside the magnetic flap forms a dead zone; as a result, both the density and viscosity of the liquid being measured increase, which causes the float to sink. As for the owner’s explanation that the float floats in an open-container because of the surrounding conditions, it can also be explained this way: the resistance to the float rising in an open container is very small, whereas in a level gauge the resistance is relatively greater, which prevents the float from rising easily
The magnetic flap level gauge is highly dependent on the specific gravity of the medium and the selection of the float. Logically, the specific gravity of a floating ball should be at least 0.05 lower than that of the liquid medium, and this applies under normal temperature conditions. Under variable temperature conditions, it is recommended to choose a specific gravity difference of 0.1 or more. This is also relatively easy to solve – just use a float ball with a density difference of over 0.1. The replacement float should ideally have a length similar to that of the waterline.
Personal opinion: First, one should doubt whether there has been a change in the density of the medium. Many production processes are highly affected by ambient temperature; when the temperature drops, light components cannot be separated properly, resulting in a decrease in density and the float sinking. Also, details are important: is there a large amount of gas released (evaporated) during evacuation? ； To what position does the float sink in the bucket? Generally, it should sink to the position of the magnet. An excess indicates that the medium has become lighter. It is also possible to test the density of the medium. Check whether the float has any cracks; when under pressure, light medium enters the float, and when the pressure is released, the medium evaporates.
I encountered the same problem at the liquid ammonia feed tank area and the liquid ammonia intermediate tank of the desulfurization project at Linfen Thermal Power Plant. The stainless steel float in the magnetic flip column has frozen. Xie Naxin, Desulfurization Instruments, Engineering Department of Jiangsu Province HG Design Institute: call: 0357-3281965, *ena*n@qq.com, January 5, 2011, night
Take it off and take a look; it’s very likely that the stainless steel float has been damaged by freezing and cracked. Here, it is common for floats to get frozen and damaged in winter.