Water infrastructure is designed around defined operating conditions, but those conditions do not remain fixed. AUMA Actuators Limited believes resilience at the valve begins by defining the full range of credible duties before the actuator is specified.
Drought, flooding, changing abstraction sources, treatment constraints, maintenance outages and emergency transfers can all require a network or treatment works to operate differently from its normal configuration.
Recent drought conditions have underlined the importance of operational flexibility. Measures such as transferring water between supply areas, adjusting pressure, changing reservoir releases and using temporary pumping arrangements can alter the duty placed on valves and associated electric actuators.
An actuator selected solely for a single, routine duty may provide insufficient flexibility when operating conditions change.
Define normal, drought and emergency duties
The starting point is the valve’s function within the process. Designers should establish how frequently it will operate, how far it must travel, the required operating time and whether it will normally provide isolation, regulation or both. They should also consider the torque or thrust required to unseat, move and reseat the valve under anticipated differential pressures.
This normal duty should then be tested against foreseeable alternative operating modes. During drought, for example, a normally static valve may be operated more frequently to support transfers or manage a different supply route. An emergency duty may require faster operation, a defined fail position or continued availability following the loss of normal power or communications.
Adam Jones, Operations Manager, AUMA Actuators Limited, explains: “Resilience depends on understanding what each asset could be required to do throughout its working life. That means looking beyond the normal duty and considering how the valve and actuator will operate during drought, maintenance, network reconfiguration or an emergency. These requirements are best addressed during specification, rather than after the equipment has entered service.”
Oversizing an actuator without analysing the valve and process does not automatically create resilience. Equally, specifying only for the most common operating condition may leave inadequate capability when the network is reconfigured.
Apply speed control for a defined process purpose
Some applications need only a fixed operating speed. Others may benefit from controlled or variable-speed movement.
Opening or closing a valve too rapidly can create undesirable hydraulic effects, including pressure transients and water hammer. Conversely, an emergency function may require a faster response than the normal process duty. AUMA’s variable-speed electric actuation solutions provide different operating speeds or movement profiles where these are required by the process.
The requirement must come from hydraulic analysis and the control philosophy. The designer should define the intended operating profile, permissible pressure changes, response time and relationship between valve position and process flow. The actuator can then be sized and configured against evidence, rather than a general assumption that either faster or slower movement is preferable.
The valve must also be suitable for the proposed regulating duty. Changing actuator speed cannot correct unsuitable valve characteristics, excessive friction or an incorrectly sized valve.
Integrate meaningful information with SCADA
A connected AUMA actuator provides more than remote open and close commands. Depending on its design and configuration, useful information may include valve position, operating state, alarms, fault indications, operating counts and diagnostic or event information.
The value of these signals depends on how they are integrated. Project teams should agree what the control room and maintenance teams genuinely need, how the information will be communicated and what action each significant alarm should initiate. Standardising interfaces and data structures where practical can help assets present information consistently across sites.
Colin Borrows, Head of UK Sales at AUMA Actuators Limited, comments: “More information does not automatically produce better decisions. The objective should be to make relevant actuator status and diagnostic information available to the people who can act on it. Effective SCADA and fieldbus integration starts with a clear understanding of the operational or maintenance decision each signal is intended to support.”
Alarm quantity is not the same as operational visibility. Poorly prioritised alarms can obscure conditions requiring attention. Communications health, timestamp consistency, event storage and the response to missing or implausible information should form part of the integration design.
Remote commands should also be subject to appropriate permissions and interlocks. Connectivity must not allow the actuator to operate outside the safe limits established by the process and valve design.
Retain local control and define failure responses
Greater connectivity does not remove the need for safe local operation. Engineers may need to inspect, test, commission or operate equipment at the valve, particularly during maintenance or a wider control-system failure.
The specification should define how local and remote modes are selected, how their status is displayed and how unintended operation is prevented while personnel are working on the asset. Manual operation should be considered as part of the complete arrangement, including accessibility and the effort required.
Loss of power and loss of communications should be treated as distinct events. The appropriate response may be to remain in position, move to a predetermined state using a suitable backup arrangement, permit local intervention or raise an alarm for an operator.
There is no universally correct fail position. The decision must reflect process safety, water quality, environmental risk and the consequences for connected assets.
Assess temporary operating changes
Temporary arrangements can become necessary quickly, but they should not bypass engineering checks. Before changing a valve’s duty, operators should confirm that the valve, actuator, gearbox, power supply and control system are suitable for the proposed operating frequency, torque, speed and duration.
They should also review interlocks, travel limits, alarm settings, communications capacity and local support. Where temporary pumps or transfer routes are introduced, the combined hydraulic behaviour of the system matters - not simply whether an individual valve can open or close.
Temporary configurations should have defined ownership, operating instructions and restoration arrangements. If an arrangement remains in use, it should be reassessed as an enduring duty rather than becoming an undocumented permanent change.
Turn operating records into better decisions
Actuator information can help establish how an asset actually operates, rather than how designers expected it to operate. Trends in operating frequency, movement time, alarms or other available information may identify changes worthy of investigation.
These records should be considered alongside valve criticality, process conditions, inspection findings and maintenance history. Used in context, they can support risk-based maintenance, help engineers investigate abnormal behaviour and improve future specifications.
Connected actuators do not independently guarantee resilience. Their value lies in providing controlled operation and credible evidence within a properly designed and managed system. Water companies can make resilience a practical capability at the valve by defining changing duties early, retaining appropriate local and failure-response arrangements, and learning from operational records.