Professional Practice in HMI Design for Process Control Rooms in the Fertilizer Manufacturing Industry in Kogi State

Process control rooms in Nigeria's fertilizer manufacturing industry, including facilities in Kogi State, North Central Nigeria, rely on human-machine interface designs that are often poorly organized for operator situational awareness, contributing to process deviations, alarm floods, and operator error under high-pressure operating conditions. This study examines professional practice in HMI design for process control applications in the fertilizer sector, guided by the ANSI/ISA-101 HMI design standard. The study applies a user-centred design evaluation methodology to the existing control room HMI systems at a urea fertilizer plant in Lokoja, involving structured observations of control room operators across four shifts, cognitive walkthrough analysis by ergonomics specialists, and a quantified alarm management assessment. Findings reveal that the existing HMI displays averaged 23 active alarms per operator-hour, far exceeding the ISA-18.2 benchmark of fewer than 6 priority alarms per operator-hour. Display colour usage violated ANSI-101 guidelines at 67 percent of reviewed screen templates, with excessive use of red and green creating visual clutter. Navigation inconsistencies between display pages were identified as contributing factors in three documented process deviation incidents within the preceding 12 months. A redesigned HMI template library conforming to ISA-101 Level 1 and Level 2 display philosophy is proposed and prototyped in Ignition SCADA for evaluation. The study provides a practical HMI redesign methodology applicable to other Nigerian process industries. Keywords: HMI design, process control room, alarm management, fertilizer plant, Kogi State