Urgent: Can a local pressure gauge and a pressure transmitter share the same pressure tapping point?
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Can local pressure gauges and pressure transmitters share the same pressure tapping point? Is there any standard or specification that specifies this? Thank you
Of course not; if port P4 is blocked or not functioning properly, both pressure readings will be incorrect! This diagram can also be modified by adding a valve after the check valve at port (6), and then installing an on-site pressure gauge behind the flange at port (6).
This post was last edited by ZhiGE on 2020-8-26 08:15. 1. SHT 3184-2017: Design Code for Automation Systems in Petrochemical Tank Areas. 2. GBT 50770-2013: Design Code for Safety Instrumented Systems in Petrochemical Industries. Using different sensor inputs helps to prevent interface blockages or other issues that could cause the instruments to fail simultaneously, thereby avoiding common cause failures and ensuring continued monitoring of process parameters.
I didn’t see any specification stating that it’s not allowed; in practice, many design firms and sites use it this way. Of course, it would be best if they could be separated, but for some equipment or reactors/vessels, there is only one port for installing instruments, so this is the only option available. I recall that according to a certain specification, for SIL level 1 (I can’t remember the level 2), it’s advisable to locate the SIS pressure tapping points separately from those of the DCS
Port 6 is a vent port and cannot be occupied
In actual production, only one port is used, and a separate root valve is required. Avoid having too many openings in the equipment.
Is the vent valve used frequently? What medium is contained in the reactor, and is on-site venting allowed? The vent port isn’t occupied! If a vent that is not used regularly is to have a valve and a pressure gauge added to it, and another port is connected as a vent, why doesn’t that work?
I know this; one is the design specification for the tank, and the other is the specification for safety interlock instruments – it’s not allowed. But can ordinary pressure pipelines or equipment be done this way?
Sure, but it’s best to keep them separate.
The design of 6 ports is for venting during startup, shutdown, or replacement, serving a function similar to that of a drain; during normal production, blind flanges are used. So there’s no need to be overly precise about it; everyone knows that normal venting requires a flare. As for whether it is possible to add local pressure gauges, it is definitely feasible in production; it just depends on whether the factory’s process workshop and safety department agree to it.