Fuel system controls

Usually, fuel systems use UL 508: Standard for Industrial Control Equipment is specified for controlling and monitoring transfer pumps, storage tanks, auxiliary tanks, polishing systems, filling systems, fuel inventory, leak detection, and other related subsystems and equipment. They offer communication capabilities for integration with a building management system, such as BACnet, Modbus, and local operating networks (LonWorks).

The control system typically uses dual independent PLCs and dual power inputs for critical applications, such as data centers, to ensure there are no single points of failure. Throughout the design process the fuel system control architecture and sequence of operations should be analyzed in detail. Preferably, the entire scope of work related to fuel systems (equipment, controls, installation, and training) should be provided by a single vendor specializing in that area.

UL 508 Standard for Industrial Control Equipment

1 Scope

1.1 Such specifications include industrial control devices and accessory devices to be used to start, stop, regulate, track, or protect electric motors. Such specifications often include industrial control devices or systems that store or process information and have the function(s) of controlling the output motors. Pursuant to National Electrical Standard, NFPA 70, this device is for use in ordinary locations. Such specifications do not provide the validation criteria for devices intended for use in practical safety applications.

1.2 These requirements cover equipment rated at or below 1500 Volts. Industrial control equipment protected by these specifications is intended for use at 0 – 40 ° C (32 – 104°F) ambient temperatures, unless explicitly specified for use under other circumstances.

1.3 Examples of industrial control devices described in 1.1 are:

1. a)    Manual, magnetic, and solid-state starters and controllers.

1. b)    Thermal, magnetic, and solid-state overload relays.

1. c)    Pushbutton stations, including selector switches and pilot lights.

1. d)    Control circuit switches and relays.

1. e)    Float, flow, pressure, and vacuum-operated switches.

1. f)    Resistors and rheostats.

1. g)    Proximity switches.

1. h)    Time-delay relays and switches.

1. i)    Resistors and rheostats intended for industrial heating and lighting, including those for motor-generator fields.

1. j)    Control devices intended for industrial heating and lighting.

1. k)    Solid-state time-delay relays.

1. l)    Programmable controllers.

1. m)    Numerical control systems.

1. n)    Lighting dimmer systems and controls.

1. o)    Mercury-tube switches.

1. p)    Definite purpose controllers.

1. q)    Solid-state logic controllers.

1. r)    Industrial microprocessor/computer systems.

1. s)    Variable voltage autotransformer.

1. t)    Motor starting autotransformer.

1.4 The requirements set out in the Standard for Industrial Control Panels, UL 508A, cover industrial control panels.

1.5 Fire pump controllers are covered by the requirements in the Standard for Fire Pump Controllers, UL 218.

1.6 The Specification for Power Conversion Equipment, UL 508C, includes an adjustable speed drive, and attachments or devices for use with an adjustable speed drive.

1.7 Equipment intended for use in hazardous locations as defined in the National Electrical Code, NFPA 70, shall be covered by the Explosion-Proof and Dust-Ignition-Proof Electrical Equipment for Use in Dangerous (Classified) Locations, UL 1203.