For the selection of level switches for special operating conditions (40 Mpa, -196°C), please give me some recommendations
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As the title indicates, a project is currently underway; it is necessary to monitor liquid levels in the system, and the installation location can be at the top or on the pipeline； The pressure within the system is 40 Mpa; the extreme low temperature is -196°C. The medium used is liquid nitrogen, and bubbles may form in a boiling state ； A differential pressure level gauge system has been adopted; to ensure accurate monitoring, an additional level switch is required. After consulting several suppliers, it has been found that the ultrasonic level switches produced by Danish API can be used for this purpose. However, the lead time for importing them is long. Is there any similar product available in China that can meet the requirements of these operating conditions? Please help recommend such products.
Please make more recommendations, and you can also discuss other types of level gauge solutions
Everyone should also recommend other possible products; thank you
If the medium is just liquid nitrogen, a float-type level gauge can be considered.
At 40 Mpa, the density difference between vapor and liquid is relatively small, and the density of liquid nitrogen is also not high, around 600 kg/m3. Additionally, the pressure resistance of the float must be taken into consideration.
A top-mounted level gauge with a float in a balanced structure can be used. The voltage tolerance is fine.
Using differential pressure transmitters remains the best solution in the air separation industry. According to SHT3007-2014, a pressure tank requires 2 sets of remote transmitters for level measurement, but it is not prohibited to use the same type of transmitter. Some experts come for inspections and unreasonably demand things from others based only on their own understanding. For newly designed projects, it is no longer recommended to use level switches; analog signals offer higher reliability. The oil depot fire and explosion in Bonsfield, UK, in 2005 was a painful lesson; the most direct cause was that the level switch did not function properly. Among numerous air separation projects, I have not yet seen liquid nitrogen tanks equipped with level switches. Generally, a thermometer is installed at the end of the storage tank overflow line (with a small section exposed to the air), and this temperature is used for interlock purposes. To meet the requirements for dual remote level measurement, I personally recommend installing an additional set of differential pressure transmitters.