Author name: Daniel Reed

Process Control Guide is a practitioner-grounded resource for engineers working with distributed control systems (DCS) and process automation. The site covers DCS architecture, vendor platforms (Emerson DeltaV, Yokogawa CENTUM VP, Honeywell Experion PKS, ABB 800xA, Siemens PCS 7), process control theory, safety instrumented systems, and ISA/IEC standards. Content is written from real plant commissioning, migration, and operations experience across industries including oil & gas, petrochemicals, chemicals, and power generation.

DCS in pharmaceutical GAMP 5 V-model validation lifecycle diagram showing the design track on the left descending from User Requirements Specification to Functional Specification to Design Specification to Configuration at the bottom of the V, with the validation track on the right ascending from Installation Qualification IQ to Operational Qualification OQ to Performance Qualification PQ, with traceability arrows linking each design specification to its corresponding qualification test, plus the regulatory framework panel showing FDA 21 CFR Part 11, EU Annex 11, and GAMP 5 ISPE requirements

DCS in Pharmaceutical: The Best Practitioner Guide to Distributed Control Systems in Pharma Plants

Daniel Reed / June 9, 2026

DCS in Pharmaceutical: The Best Practitioner Guide to Distributed Control Systems in Pharma Plants By Daniel Reed / June 23, […]

DCS in LNG overview diagram showing all major units of a liquefaction train — feed gas reception with metering and gas chromatography 1,000 to 2,000 I/O, AGR amine treating for H2S and CO2 removal 2,000 to 3,500 I/O, molecular sieve dehydration 1,500 to 2,500 I/O, mercury removal protecting aluminum equipment 500 to 1,000 I/O, heavies removal 1,500 to 2,500 I/O, and the liquefaction section as the heart of the plant containing propane refrigeration with 30 to 50 MW driver, the Main Cryogenic Heat Exchanger cooling to -160 degrees Celsius, and mixed refrigerant compression with 50 to 130 MW driver totaling 4,000 to 7,000 I/O, plus LNG storage in 160,000 to 250,000 cubic meter tanks, LNG loading with cryogenic marine arms, and utilities and offsites 5,000 to 10,000 I/O

DCS in LNG: The Best Practitioner Guide to Distributed Control Systems in LNG Plants

Daniel Reed / June 9, 2026

The gas-to-liquids facility in Africa where I spent several years earlier in my career wasn’t an LNG plant — it

DCS in refining overview diagram showing all major refinery units and their I/O scale — crude oil feed entering the Crude Distillation Unit with 2,000 to 4,000 I/O, then Vacuum Distillation Unit with 1,500 to 2,500 I/O, feeding the conversion units including FCC with 3,000 to 5,000 I/O as the most complex unit, Hydrocracker with 4,000 to 6,000 I/O, Reformer with 2,000 to 4,000 I/O, and Delayed Coker with 1,500 to 2,500 I/O, plus treating units (naphtha, diesel, FCC feed hydrotreaters, alkylation, sulfur recovery) and utilities and offsites totaling 20,000 to 50,000 I/O for a large integrated refinery

DCS in Refining: The Best Practitioner Guide to Distributed Control Systems in Petroleum Refineries

Daniel Reed / June 9, 2026

The refinery I most often visit on the large oil and gas mega-project in Asia isn’t technically a refinery —

ISA-95 Purdue Reference Model diagram showing all six levels of the manufacturing integration hierarchy — Level 0 physical process at the base, Level 1 sensing and controllers, Level 2 supervisory control and HMI, Level 3 manufacturing operations management with MES and historian, Level 4 site business planning with ERP, and Level 5 enterprise corporate at the top — with the ISA-95 primary interface highlighted at the Level 3 to Level 4 boundary and four categories of information exchange shown at the bottom

ISA-95 Enterprise Integration: The Best Practitioner Guide for Process Engineers in 2026

Daniel Reed / June 8, 2026

The first time the Purdue model became real to me wasn’t in a training session — it was during a

ISA-18.2 alarm management lifecycle diagram showing all ten stages arranged in a continuous improvement cycle — Philosophy as the foundational document, Identification of candidate alarms, Rationalization against philosophy criteria, Detailed Design with setpoints and deadbands, Implementation in the DCS, Operation in active daily use, Maintenance for recalibration and suppression updates, Monitoring and Assessment of performance KPIs, Management of Change for formal MOC discipline, and periodic Audit verification of ongoing compliance

ISA-18.2 Alarm Management: The Best Practitioner Guide for Process Engineers in 2026

Daniel Reed / June 8, 2026

I learned what an alarm flood actually looks like during a process upset on the offshore brownfield in Africa, around

ISA-101 versus traditional HMI design comparison showing dense saturated colored screen on the left with bright red vessel, blue pump, multiple bright numeric values and skeuomorphic equipment shapes that hide the abnormal high-pressure alarm versus ISA-101 high-performance HMI on the right with muted gray normal state showing functional schematic symbols where the single red alarm and red abnormal value visually dominate the screen

ISA-101 HMI Design: The Best Practitioner Guide for Process Engineers in 2026

Daniel Reed / June 8, 2026

The moment I understood why ISA-101 matters wasn’t in a training session or a standards document. It was in the

DCS vs SCADA vs PLC three-way architecture comparison diagram showing DCS as integrated platform for continuous process control inside a single facility on the left, PLC as single controller for discrete and OEM equipment in the middle, and SCADA as software architecture for wide-area supervisory monitoring of multiple distributed sites on the right, with when-to-use guidance and typical vendor examples for each

DCS vs Other Systems

DCS vs SCADA vs PLC: The Best Practitioner Guide for Process Engineers in 2026

Daniel Reed / June 8, 2026

On one of the offshore brownfield projects I worked on in Africa, I had the unusual experience of seeing all

DCS vs SCADA geographic scope comparison diagram showing DCS architecture inside a single plant fence with redundant control network connecting controllers and operator stations on the left versus SCADA architecture spanning multiple distributed remote sites with RTUs and PLCs communicating to a central master station over wide-area network on the right

DCS vs Other Systems

DCS vs SCADA: The Best Practitioner Guide for Process Engineers in 2026

Daniel Reed / June 8, 2026

The first time I had to draw the architectural line between DCS and SCADA was on a midstream gas project

DCS vs PLC architecture comparison diagram showing integrated DCS distributed control system with unified operator stations and redundant controllers on the left versus PLC plus SCADA architecture with separately-procured software and modular PLC controllers on the right

DCS vs Other Systems

DCS vs PLC: The Best Practitioner Guide for Process Engineers in 2026

Daniel Reed / June 8, 2026

The first time I worked on an EPC project where the wrong control system was chosen, it cost the operator

Ratio control architecture diagram showing the wild stream flow transmitter feeding into a multiplier block with operator-adjustable ratio target, generating the setpoint for a PID controller that drives the controlled stream's control valve and final element

Process Control Theory

Ratio Control Explained: The Best Practitioner Guide for Process Engineers in 2026

Daniel Reed / June 8, 2026

The first ratio control loop I commissioned was an air-to-fuel ratio controller on a fired heater on a gas-to-liquids facility