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Topic Title: The use of Z in instrument ID's
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Created On: 31 January 2013 01:45 PM
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 31 January 2013 01:45 PM
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Does anyone know if the use of Z in an instrument ID to distinguish that the instrument is part of an emergency trip system is specified anywhere? I know it is used as a first letter for Position/Dimension as in "ZIT" to show a position transmitter with local indication. However we have a project on site that uses Z as the second letter to designate that the instrument is part of the Emergency Shut Down System as apposed to being used solely for control or indication. We have a new project coming up and the question has been raised as to the correct use of Z.

Would appreciate if anyone has more detail on this. If it is specified anywhere then will clear up any arguments that may ensue.
 31 January 2013 10:00 PM
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I don't think it's in any of the international standards such as ISA S5.1, but it's certainly widely used, e.g. Shell, Chevron et al.

Reality is that which, when you stop believing in it, doesn't go away.
 13 February 2013 02:43 PM
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ISA 5.1 Figure 7.9 does contain use of letter Z, both for positional and SIS.

So, a ZT may be a position transmitter, whereas a TZH may be a high temperature trip.

more reading here > < page 105

Edited: 13 February 2013 at 02:54 PM by chartassuk

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