Advanced Process Control & Safety Instrumented Systems SIS

Explore advanced process control across process industries, mastering precise regulation of level, temperature, pressure, and flow in reactors and distillation columns, with safety instrumented systems and pid representations.

Explore advanced process control techniques used in the process industry and learn about safety instrumented systems, interlocks, and alarms. Access downloadable PDFs in the resources to supplement learning.

Identify when to control a piece of equipment and design a control system around it, covering pumps, compressors, heat exchangers and furnaces, and read process control schemes.

Disturbances drive the need to control equipment. When a system isn’t self-regulating and disturbances are not tolerable, most equipment requires control; process items are almost never self-regulated.

Install control loops around equipment to bring it into its operating window by regulating the main parameter (temperature, flow, pressure, or composition) and assess risk to determine SIS needs.

Learn pipe control across three scenarios: single pipe flow, diverting flow to multiple branches with valves, and merging streams, focusing on the simultaneous function.

Explore how partially closing a control valve increases downstream pressure drop, reduces flow, and why placement depends on whether you must control pressure or flow.

Explore how pressure along a pipe is shaped by friction and fittings, and compare two upstream pressure control options using a pump or valve to maintain a target inlet pressure.

Assess whether to control flow in a pipe. Use one or two valves based on end pressures; flow depends on P1 and P2, needing two loops if both vary.

Explore flow merging in multiple connected pipes, distinguishing merging for gathering, blending, make-up, or backup, and apply ratio and cascade control to manage composition and flow.

Explore flow splitting control, including how to allocate total flow to parallel destinations, use level or flow loops to prevent flooding or plugging, and prefer controlling the smaller-flow branch.

Explore PID control for centrifugal pumps and compare capacity and minimum flow control, including discharge throttling with valves versus variable speed drives, and explain split-range loops.

Compare control valves and VFD for centrifugal pump control, including split-range options, and decide whether to place a valve in the discharge line or a VFD on the motor.

Explore minimum flow control for centrifugal pumps using a recirculation line, sensors, and valves to maintain 100 m³/h, with guidelines by pump size and parallel pump arrangements.

Learn to control positive displacement pumps, which require different capacity-control methods than centrifugal pumps: a recirculation pipe or a variable speed drive.

Learn how to control a positive displacement pump's capacity using a recirculation pipe, with back pressure or level/flow control loops, while noting discharge throttling alone is ineffective.

Use a VFD to control a positive displacement pump by varying shaft speed through a flow loop, with a discharge flow sensor feeding the controller.

Adjusts the third type of positive displacement pump control by using a servo motor on stroke adjustment lever in reciprocating pumps, with the flow control loop signaling to regulate flow.

Explore gas mover control systems for compressors and turbines, differentiating dynamic and positive displacement types and applying capacity and surge protection, including anti surge for centrifugal movers.

Examine five control methods for gas movers: recirculation, speed control, section throttling, discharge throttling, and special methods. Learn when each is economical and how flow or pressure loops apply.

Apply anti surge protection for gas movers using a recirculation valve and pressure differential and flow monitoring to prevent surge when differential exceeds 15 kPa and power exceeds 150 bhp.

Control heat exchangers by placing a temperature sensor on the target stream and placing the valve on the non-target stream; compare direct throttling and bypass control.

Use direct control for heat exchangers by throttling cold stream to regulate hot outlet temperature, ideal for utility heat exchangers but not for process heat exchangers due to downstream impact.

Use bypass control to regulate hot outlet temperature by throttling the bypass valve while keeping total cold flow constant; discuss series/parallel exchangers and a bypass pressure differential controller.

Learn how air cooler control uses temperature loops to regulate louvers, blade pitch, and fan speed, including suction-based, throttling, and variable speed drive with three-range split range.

Demonstrates how heat exchangers may require no control to maximize heat transfer in heat recovery, while cold-stream temperature may require control, and utility exchangers also need a control system.

Learn how downstream pressure control with a pressure loop or back pressure regulator maintains adequate flow for efficient heat exchange when hydraulic features limit the temperature control loop.

Control reactor temperature with jackets or external coolers using cascade loops and temperature-to-temperature schemes. Improve yield, composition, and product quality with process analyzers and split range control.

Explore fired heater control using coil outlet temperature, skin temperature, pass balance, and firing control, with cascaded temperature and flow loops, airflow management, and excess air strategies.

Explore advanced fired heater control for fuel gas with variable heating value, using a Wabi index analyzer and flow meter to regulate heat via heating value rate.

Master container and vessel control by comparing upstream and downstream level strategies, illustrating surge dampening, feed tanks, surge tanks, and cascade control with two tanks in series.

explore how blanket gas creates a positive cushion above the liquid surface in a tank using inlet and outlet regulators, back pressure and flow regulators, and oxygen monitoring.

Learn safety instrumented systems interlocks and alarms after basic process control, and read motor control, FGS, and alarms on Nids to assess safe operating limits and compliance.

Explore how safety strategies manage process parameters using BPCS and SIS, including alarms when control shifts to CIS, four methodologies: inherent design, passive, active, procedural actions, and standards.

Explore the concept of safety instrumented systems (SIS) as a set of CIF safety instrumented functions that act like operator responses when alarms sound, restoring the process to safe operation.

Explore how safety instrumented systems trigger emergency shutdown, emergency isolation, emergency depressurizing and blowdown, HIPPS, and burner management to protect plants, limit releases, and prevent escalation.

Explain how safety instrumented systems hold the plant in a safe window by plant-wide and equipment-level strategies, and outline four tiers: equipment, system, unit, and plant.

Decide how to install a CIS function for a piece of equipment by using qualitative Hazop-based assessments and targeted quantitative SIL evaluations, then apply LOPA to determine protection layers.

Explore the cis concept where sensors feed a plc-based logic solver to drive an actuator, with manual override and alarms at high/high or low/low points, 5–30 minutes before activation.

Explore the anatomy of a SIS size function, uncovering the primary element, the final element, and the logic solver, with future videos detailing NID symbology.

Explore how SIS sensors use process parameters—pressure, flow, level, temperature—with high and low triggers (hh, h, ll, l), and the role of non process parameters and switches.

Identify CIS final elements that initiate and stop flows, including electrical motor switches and remotely operated switching valves with transducers converting electrical signals to pneumatic signals.

Learn to determine from the valve symbol whether the actuator is spring-loaded or double-acting, using three-way and four-way valve examples and the fail-open default.

Learn how limit switches attached to a valve stem provide real-time position feedback, showing open or closed status to operators via a control room indicator.

Assess the feasibility of merging a control valve with a switching valve, and identify how the solenoid arrangement on the instrument air input signals a merged control and safety logic.

Safety PLCs control the CIS function and use a diamond-shaped symbol to represent the PLC. CIS logic uses a diamond on needs as its specifying characteristic.

Explore how safety instrumented functions (CIS) are shown on P&IDs, addressing crowdedness and interpretation challenges using cause and effect tables and interlock tags.

Discrete control, part of a bpcs action, uses on-off switching valves for non-continuous or batch processes, functioning as a process interlock rather than a safety interlock.

Learn how alarm systems warn operators when a process variable exceeds its acceptable envelope before SIS activation, and how fire and gas detection systems respond after loss of containment.

Explore the anatomy of alarm systems, from sensor or switch to logic processor and alarm, including hard and soft alarms and DCS or PLC, linked to level, flow, temperature, pressure.

Decide which parameters need alarms and the triggering level, balancing too few or too many alarms. Use bands, pre alarms, and alarms with two or three levels to guide actions.

Learn how sensors feed alarm logic through plc or dcs, with alarms in bpcs, sis, or servers. Explore annunciators and field versus control room alarms and their symbols on Nids.

Learn how multiple alarm loops merge into a single annunciator in common alarm systems, obscuring fault locations and prompting investigation, as seen in electric motors.

Fire and gas detection systems monitor fire and non-innocent gases in process spaces and trigger alarms or actions, focusing on signal handling and sensor/alarm location.

Explore how electric motor control is depicted across companies, and learn three categories: commands, reports, and hand-off auto switches in the motor control center.

Explain motor command signals and health indicators on nid diagrams, distinguishing field activated versus control room origins, and show responses with i, a, and l indicators and nonstandard symbols.

Explore the ID representation for electric motor inspection and repair, focusing on HOA switch positions—off, hand, auto—remote vs local control, field push buttons, and DCS visibility.

Access downloadable resources that support learning in advanced process control and safety instrumented systems (SIS).

Explore bonus material on advanced process control and safety instrumented systems (SIS). Strengthen understanding of process control and SIS concepts.