Can 2 pressure transmitters share one pressure tapping tube?
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Can 2 pressure transmitters share one pressure tapping tube, with both participating in interlock functions? Typical designs do not consider sharing one pressure tapping point for two pressure transmitters, but no relevant specifications were found. Please, expert, provide the relevant specifications.
Sure! It’s not particularly strict or fussy; it’s useful on-site. I’m not sure about the specific specifications either.
It is not recommended to share a pressure tapping pipe for two transmitters from the perspectives of safety and maintenance.
The main question is whether it’s really necessary; if so, it’s fine to connect N units
It is not possible to consider using one pressure tapping point for two pressure transmitters (N points on a single pressure tap can be regarded as one pressure tapping point); this is especially true in the case of interlocks, as any issue with the pressure tapping point will prevent both instruments from functioning properly. The two pressure transmitters should have two pressure tapping points, which can be adjacent front to back or side by side (ensuring the pipe diameter is sufficient).
There are several such flow meters in use for hydrogenation processes at the plant; they are orifice plates. Two sets of pressure tapping pipes are used to take pressure readings from these orifice plates, and four pressure transducers are connected to them. These instruments are used for three-out-of-two interlock functions as well as control purposes – four instruments in total, with three for interlocking and one for control.
If it can be ensured that the pressure guide tube is never blocked at any time, then two pressure gauges or pressure transmitters can share one pressure sampling tube. However, when the medium is such that it cannot be guaranteed to remain unobstructed—such as viscous media that may produce solids, powders that could accumulate, or media that may form precipitates or crystals—it is advisable to use two pressure transfer pipes in such cases. There should be conditions attached to asking such questions; industrial situations are specific, and it is unobjective to ask questions in a general manner without taking into account the actual conditions on site and the properties of the materials involved.
It is recommended to use them separately; it’s also okay not to, but it is not advised.