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I am interested in feedback on using Equipment tagging instead of ISA loop number tagging. (My experience is the Hydrocarbon Process Industry -
perhaps other industries have already solved this issue.)
ISA S5.1 - Instrument Symbols and Identification does a fairly good job of providing a method of naming instrument tags that are part of a process
loop. When ISA S5.1 is used to identify "tags" associated with process equipment/valves there are many who feel it comes up short. The
proliferation of HS's, XY's and ZSs do not provide clarity.
One important reason for this short fall is the fact that tags associated with equipment do not fit ISA's process loop numbering model. In the loop numbering model the object is the loop, i.e., F01. The attributes of the tag are instruments, i.e, FE-01, FT-01, FIC-01, FV-01.
With equipment tags, I feel the object should be the equipment, i.e., a pump P101. This fits with the digital compound points that are available in most DCSs. Some attributes of the pump that need to be identified would be the control command, P101-C, the run status, P101-S. The "hand switch" in the DCS would be the object itself, P101. The name of the object is assigned by the process engineer and shown on the P&ID.
An important advantage with this method is that the wire labels become self documenting. No more XY-435 for the P101 control command and HS-757 for the associated hand switch. (I am sure there are many who have spent hours trying to get the loop numbers to line up somehow.) If I'm looking at wires that are labelled MOV-101-OP and MOV-101-CL trouble shooting is much improved.
In the same way limit switches and open/close commands can be considered attributes of the valve object. FV01-OPND, FV-CLSD, FV01-OP and FV01-CL. There is no need for a separate ZSC-325A/B or XYs. In fact the notion of a Z325 being a process loop is false - except maybe for a positioner. The position of the valve is an attribute - it is not an equipment object or
process loop object.
I am hopeful that the above changes will move intrument tagging closer to a object.parameter naming without throwing away years of good instrument tag numbering. If you have standards that I could use for equipment object parameter naming I would be most interested.
perhaps other industries have already solved this issue.)
ISA S5.1 - Instrument Symbols and Identification does a fairly good job of providing a method of naming instrument tags that are part of a process
loop. When ISA S5.1 is used to identify "tags" associated with process equipment/valves there are many who feel it comes up short. The
proliferation of HS's, XY's and ZSs do not provide clarity.
One important reason for this short fall is the fact that tags associated with equipment do not fit ISA's process loop numbering model. In the loop numbering model the object is the loop, i.e., F01. The attributes of the tag are instruments, i.e, FE-01, FT-01, FIC-01, FV-01.
With equipment tags, I feel the object should be the equipment, i.e., a pump P101. This fits with the digital compound points that are available in most DCSs. Some attributes of the pump that need to be identified would be the control command, P101-C, the run status, P101-S. The "hand switch" in the DCS would be the object itself, P101. The name of the object is assigned by the process engineer and shown on the P&ID.
An important advantage with this method is that the wire labels become self documenting. No more XY-435 for the P101 control command and HS-757 for the associated hand switch. (I am sure there are many who have spent hours trying to get the loop numbers to line up somehow.) If I'm looking at wires that are labelled MOV-101-OP and MOV-101-CL trouble shooting is much improved.
In the same way limit switches and open/close commands can be considered attributes of the valve object. FV01-OPND, FV-CLSD, FV01-OP and FV01-CL. There is no need for a separate ZSC-325A/B or XYs. In fact the notion of a Z325 being a process loop is false - except maybe for a positioner. The position of the valve is an attribute - it is not an equipment object or
process loop object.
I am hopeful that the above changes will move intrument tagging closer to a object.parameter naming without throwing away years of good instrument tag numbering. If you have standards that I could use for equipment object parameter naming I would be most interested.