Does calculating temperature for two channels not count as two sensors?
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Can a pair of thermometers in a temperature jacket on a reactor be considered two sensors? Is it possible to send one set of sensors to the DCS and another set to the SIS system? Are there any regulations requiring that sensors sent to the DCS system and those sent to the SIS system be installed in different locations? Thank you so much!
I think it’s not possible; mainly, during maintenance, it might cause issues
No, SIS and DCS must be separated; two temperature sensors are required. Another approach is to send the temperature signal to the SIS first, and then route a signal from the control cabinet to the DCS.
A dual-element thermometer definitely has two elements, but using it simultaneously for both SIS and DCS does not meet the requirements
If this is a modification and there are no other ports available, then having to share one measurement point is still acceptable. For new projects, it is best not to share the same measurement point for the temperature sensors of DCS and SIS. There is a common cause failure issue
Principles of independence, effectiveness, and auditability
This is possible; although the two thermometers are at the same measurement point, they provide two different temperature readings
The dual-thermometer type is a structural design for instruments; both the certification and other aspects are considered as pertaining to a single instrument. Personally, I think this approach is not appropriate.
…………Our company has several batch DCS and SIS systems that use the same sleeve for temperature measurement, with two temperature sensors; there are no additional ports available on the tank, :)
No, the sis unit should be independent; otherwise it will affect maintenance
The 5th floor is the correct choice; design projects from before 2012 could be used in this way, but it’s recommended to keep new projects completely separate. If security experts say it’s not feasible, then it indeed isn’t feasible