Automation of Water Resource Recovery Facilities. Water Environment Federation

process. Such add-ons allow users to insert equipment “blocks” that automatically draw equipment, add connecting lines, and insert “text bubbles” identifying the parts. The blocks also contain equipment specifications such as size and identification number. As each equipment block is placed on the drawing, the software creates a related database that can serve as an equipment list (Bentley Systems, Incorporated, http://ftp2.bentley.com/dist/collateral/docs/case_studies/GWFACaseStudy_0712.pdf). More information on CAD software can be obtained by using any Internet search engine.

2.2 Instrument List

      An instrument list provides more information on each instrument in the project P&IDs. It notes the instrument’s tag number; process signal range (the minimum and maximum values that the instrument is to be calibrated for in engineering units; this is different from the instrument design range listed in the instrument specification); specification reference (detailed instrument specifications are located elsewhere in the project specifications and are referenced by their respective specification section); and drawing reference numbers (P&ID, location, etc.).

2.3 Input/Output List

      An I/O list tabulates the actual input and output points for each signal shown in P&IDs. It describes each point, noting its type (digital or analog input or output), associated PLC or DCS processor, and engineering units (units of measure that are useful for operators). The I/O lists are also used to identify internal addresses or I/O points transmitted via a data link for data and/or control that need to be transmitted between a PLC and human–machine interface/supervisory control and data acquisition (SCADA) software or other PLCs, DCSs, VFDs, and motorized valve networks.

2.4 Panel List

      A panel list is a complete list of all control panels and is intended to aid contract bids. It includes each panel’s location, National Electrical Manufacturers Association (http://www.nema.org) rating, and supplier.

2.5 Cable and Conduit List

      A cable and conduit list tabulates instrumentation-wiring requirements, including power, other electrical, and any special manufacturer’s cables, and the quantity furnished with the instrument (e.g., magmeter’s primary cable, float-switch cable, etc.). Depending on the organization, this list may be part of the I&C or electrical designs. The purpose of this chapter is to advance the concept that P&IDs are the starting documents used by others to create complete automation design documents. Therefore, it is important to emphasize that practitioners should prepare these supporting documents as part of total automation design using P&IDs as one of the documents used to aid them in preparing these lists. Moreover, they should avoid jumping directly from P&IDs without other supporting documents (e.g., manufacturer equipment wiring diagrams for specified equipment, circuit wiring diagrams, etc.).

2.6 Process Control Narratives

      Process control narratives (PCNs) describe the strategies and exact sequence of events to operate all I&C equipment automatically or manually. This narrative can be an outline of the necessary steps (the most common option), a Boolean logic diagram, a sequential function chart, a flow chart, or a ladder logic diagram (see Chapter 5 for additional information).

2.7 Panel and Field Instrument Specifications

      Detailed specifications of all panel and field instruments typically are prepared in Construction Specifications Institute (CSI) format by design engineers as part of the contract documents. The CSI specifications are not a substitute for ISA specification forms, although there is some overlap in these documents. Owners and engineers should require that completed ISA forms be provided by the system integrator as part of a complete set of submittals to ensure compliance with contract requirements and uniformity of the information provided (see the “Specifications” section in Chapter 6 for more details). Instrument specification forms are also available from the ISA in both paper and electronic formats. International Society of Automation specification forms, which are typically provided by system integrators and those responsible for actual procurement of instruments, address the following:

      • Type of instrument;

      • Materials of construction for wetted and nonwetted parts;

      • Process and environmental conditions in which the instrument is used (i.e., outdoors, corrosive area, or hazardous area);

      • National Electrical Manufacturers Association rating;

      • Power requirements;

      • Signal output requirements;

      • Alarm signal requirements, if any;

      • Special mounting hardware required;

      • All options to be furnished;

      • Instrument span, calibrated range, and engineering units;

      • Process connections (e.g., size and type of connections, i.e., flanged or threaded);

      • Transmitter requirements (i.e., whether remote or integral to sensor); and

      • Manufacturer model numbers (note that specific manufacturer model numbers will depend on the selected manufacturer after the bid is awarded).

      It is also a good idea to include any manufacturer support services required for successful installation, calibration, training, and startup of the specified instruments (see Chapters 8 and 9 for more details). This is important for specialty items or most analytical or water quality analyzers.

      However, because most public works projects require competitive bidding for procurement, the design engineer’s specifications should be general enough to enable several reputable vendors to bid on the project, but detailed enough to supply them with the necessary information to realistically bid. It is incumbent on the design engineer to possess the knowledge and skill to offer this balance. Providing detailed instrument specifications using ISA forms could be a bid-submittal requirement for I&C contractors.

2.8 Electrical Schematics

      Electrical schematics of some instrumentation systems may be needed to illustrate wiring details not apparent in P&IDs. Consulting engineer designs typically include these schematics with electrical design documents. In addition, vendor electrical equipment-related submittals, which show the exact wiring requirements for the specific equipment furnished on a project, typically are one of the last sets of submittals that are approved on complex projects. These key submittals have a direct effect on the actual wiring drawings needed for construction by the installing contractor.

2.9 Instrument Loop Diagrams

      Loop diagrams are an important part of I&C design. However, because they are specific to the actual devices used, they cannot be created until the system integrator has been selected and the user or design engineer has accepted all instruments, control panels, control systems, valves, and so on. Loop diagrams typically are prepared by the I&C contractor or system integrator, not the design engineer. In some instances, end users with available staff may choose to prepare these in-house. (For specific guidance on preparing loop diagrams, see ISA Standard S5.4 [Meier and Meier, 2011].)

2.10 Equipment Location Drawings

      Equipment location drawings are mechanical