How is the range of a liquid nitrogen tank calculated?
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There is a liquid nitrogen tank from 2002 that has not been in use until now and is now set to be put into operation. The level gauge that was used for a long time – originally a mechanical 4-20mA gauge of a domestic brand without a Hart protocol – is now broken, and no gauges of the original type are available. It is planned to replace them with Rosemount gauges. The range indicated on the original gauge was -200 to 850 degrees Celsius (which seems unreasonable). So, how should the range be calculated? Is the density on the negative pressure side calculated based on nitrogen? I hope experts can help solve this issue.
This post was last edited by ylb913 on 2015-9-13 at 19:46. There used to be liquid ammonia storage tanks in use, which served for over ten years; their density was around 0.6. On many occasions, we didn’t have a DCS system nor any remote level indication, so operations were carried out by looking at the glass gauges on site. It’s a bit silly too; the liquid level indicated by DCS is simply a matter of differential pressure. When the differential pressure is at its maximum, it’s 100%, and when it’s 0, it’s 0%; the values in between are distributed equally.