Do the so-called independent level gauges and pressure transmitters in the SIS system require separate pressure transfer pipes?

According to the relevant standards I am aware of, independent level gauges and pressure transmitters require separate pressure tubes and should not share them with other equipment. This is to avoid cross-interference within the same pressure tap, thereby affecting the accuracy and reliability of the system’s measurements. When upgrading old installations, the additional level gauges and pressure transmitters should also be equipped with separate pressure tapping pipes. It is recommended that, during the design, installation, and commissioning of the SIS system, operations should be carried out in accordance with relevant standards to ensure stable and reliable system operation, as well as to enhance the system’s security and accuracy. You may refer to the standard **“Requirements for Safety Interlock Systems in Industrial Production Processes”** and ISA-84.00.01-2004 **“Specification for Functional Safety Requirements of Safety Instrumented Systems”.** -

Independence； Refer to \"Functional Safety of Safety Instrumented Systems in the Process Industry\" (GB/T21109-2007)

Is it possible to have separate level gauges and pressure transmitters while the pressure lead pipe is not separate? What’s going on here? I don’t understand.

Firstly, in accordance with the requirements of the current GB50770-2013, measuring instruments and sampling points should be installed separately; the measuring instruments of the safety instrumented system should be separate from those of the basic process control system. For measuring instruments that share the same instrument housing as those in the basic process control system, the sampling points, pressure lead pipes, sensors, etc., of the safety instrument system’s measuring instruments should be installed separately and should not be shared with the basic process control system.