Sealed windows for viewing interior components;
• Thermal management;
• Supports (wall-mounted or floor-mounted);
• Method of compliance with area classification (purging, explosion-proof, etc.); and
• Agency approval (Underwriters Laboratories’ [2009] 508 listing).
2.1.1.4 Operator Interface Terminals
The following items should be considered when specifying operator interface terminals:
• Panel-mounted, pedestal, or desktop;
• Personal computer tablets and smartphones;
• Operating system if using a personal computer; and
• Area classification, where located.
2.1.1.5 Panel-Mounted Devices
The following items should be considered when specifying panel-mounted devices:
• Pilot lights, including colors and types (light-emitting diode, incandescent, neon, push-to-test functions, physical size, NEMA rating, voltages, etc.);
• Pushbuttons (sizes, colors, NEMA rating, voltage rating, maintained or momentary contacts, and operator type);
• Selector switches and potentiometers (sizes, NEMA rating, voltages, maintained or momentary contacts, and maximum resistance value for potentiometer);
• Strobes (lens colors, NEMA rating, voltages, and mounting);
• Horns (decibel rating, voltages, and NEMA rating);
• Terminals (fused, nonfused types, density, voltage rating, etc.);
• Surge protection devices (types per Underwriters Laboratories [2009] UL 1449, 3rd edition); and
• Panel wiring (wire markers and wire terminations) such as
2.1.1.6 Networking Equipment
The following items should be considered when specifying network equipment:
• Ethernet switches (managed vs unmanaged, industrial vs office grade, number and type of ports, etc.);
• Routers (rack-mount vs shelf-mount, built-in firewalls, number and types of ports, management software, etc.);
• Network racks (standard rack size based on the number of rack units required by components within the rack); and
• Network security (hardware and software).
2.1.1.7 Input/Output List
In addition to the I/O list, a monitored variables list should be compiled in a table (see Table 3.2 for an example). The table should note each variable’s anticipated range, whether a setpoint is required, and whether it is fixed or adjustable (all setpoints should be made adjustable unless otherwise specified by the equipment manufacturer, warranty, or other applicable authority). The table should note the initial setting of each setpoint, if available, who can change it (e.g., operator, supervisor, process engineer, maintenance technician, facility superintendent, system administrator, etc.), and whether it should be password protected.
2.1.1.8 Instrument List or Index
Complete instrument lists help a contractor to accurately bid and procure instruments. Instrument lists can take the form of a spreadsheet or database for easy sorting by various criteria (e.g., flow meters, pressure transmitters, etc.). An instrument list can also be used as a checklist by the design team to ensure that all devices have been accounted for. At a minimum, an instrument list should include the following:
• Tag number as listed in the P&ID,
• Description of instrument,
• Technical specification section,
• Calibrated-range setting,
TABLE 3.2 A sample list of monitored variables.
• Setpoints for discrete devices,
• Location of the P&ID,
• Physical location drawing number, and
• Remarks section for any additional information.
2.1.1.9 Network Cabling
The following items should be considered when specifying network cabling (see Chapter 11 for additional information):
• Fiber optics (fiber terminations including patch panels and patch cables; use of patch panels is a highly recommended method of fiber cable management for termination of fibers including spares at control panels
