The `pumpingStation` node models an S88 **Process Cell**: a wet-well basin with inflow and outflow, wrapped around one or more pump controllers. Every second it recomputes the basin's water balance, picks the most trustworthy net-flow source, runs its safety interlocks, and finally commands its children (individual pumps, `machineGroupControl`, or nested pumping stations) so the level stays inside the safe operating band.
This page is the operator-facing reference, derived from [`src/specificClass.js`](../src/specificClass.js). For the 3-tier code layout see [EVOLV — Node Architecture](https://gitea.wbd-rd.nl/RnD/EVOLV/src/branch/main/wiki/architecture/node-architecture.md); for the atomic pump model see the [rotatingMachine wiki](https://gitea.wbd-rd.nl/RnD/rotatingMachine/wiki).
> **Diagrams on this page are editable.** Sources live in [`diagrams/`](diagrams/) — open the `.drawio` file in [draw.io](https://app.diagrams.net/), export to SVG, commit. See [`diagrams/README.md`](diagrams/README.md).
1.**Construct.** The node merges the user's editor config over the schema defaults, creates the measurement store, and seeds the predicted volume at the basin's operational floor (`minVol`).
2.**Register children.** Sensors, pumps, machine groups, and nested stations register via the Port-2 handshake. The station subscribes only to the *highest-level aggregator* for predicted flow to avoid double-counting (MGC if present, otherwise the individual pump).
| **Inlet Elevation (m)** | `2` | Bottom/invert of the incoming sewer pipe, measured from the basin floor. This is the level where backing up into the inlet starts to matter hydraulically. |
| **Outlet Elevation (m)** | `0.2` | Top of the pump-suction/outlet pipe, measured from the basin floor. This is the practical lower hydraulic reference for pump protection. |
| **Inlet Pipe Diameter (m)** | `0.4` | Nominal incoming sewer pipe diameter. Used with `inflowLevel` to distinguish pipe bottom, centre, and crown in future hydraulic upgrades. |
| **Outlet Pipe Diameter (m)** | `0.4` | Nominal pump-suction/outlet pipe diameter. Used with `outflowLevel` to distinguish pipe top, centre, and invert in future hydraulic upgrades. |
| **Overflow Level (m)** | `2.5` | Physical overflow-weir crest, measured from the floor. At or above this level the basin is actually spilling. |
Constant cross-section is assumed: `surfaceArea = volume / height`. All derived volumes (`minVolAtOutflow`, `minVolAtInflow`, `maxVolAtOverflow`, `maxVol`) are computed once in `initBasinProperties()` and kept on `station.basin`.
The current runtime still uses the level fields directly for its volume math. Pipe diameters are part of the basin model contract so later hydraulic logic can reason about pipe invert/crown and not silently treat every pipe elevation as a centreline.
| **startLevel (m)** | `1` | Mode-specific threshold. In `levelbased`, this is the bottom of the linear scaling range (0 % demand). It is not part of the generic basin model because other modes can define a different start policy. |
| **maxLevel (m)** | `4` | Upper normal operating/storage level used by the active mode. In `levelbased`, this is where demand reaches 100 %. |
| **Low Volume Threshold (%)** | `2` | Safety margin above the configured minimum volume: `dryRunSafetyVol = minVol × (1 + pct/100)`. This creates `dryRunLevel`; it is derived, not a separately entered basin height. |
| **Enable Overfill Protection** | `true` | If on, upstream inflows are shut down once volume climbs above the high-volume safety point while filling. |
| **High Volume Threshold (%)** | `98` | Safety margin below physical overflow: `highVolumeSafetyVol = maxVolAtOverflow × pct/100`. Actual overflowing is still the boolean condition `level >= overflowLevel`. |
> **Tip — always configure every field.** The pumpingStation mixes geometry and control thresholds freely. Leaving `overflowLevel` at the schema default of 2.5 m while sizing the basin for 10 m walls produces nonsensical fill-percentages and spurious safety events. See the [EVOLV flow-layout rules §9](https://gitea.wbd-rd.nl/RnD/EVOLV/src/branch/main/.claude/rules/node-red-flow-layout.md) for the completeness rule.
All commands enter on the single input port. `msg.topic` selects the handler; `msg.payload` carries the argument.
### `changemode`
```json
{ "topic": "changemode", "payload": "manual" }
```
Switches the active control strategy. The new mode must be in `config.control.allowedModes` — unknown values are rejected with a warning. Typical transitions: `levelbased ⇄ manual` for operator override during maintenance.
Hard-reset the predicted volume time-series to the supplied value (m³). Also rewrites the predicted level (derived from the constant-area geometry) and resets the internal flow-integrator state. Use this when a trustworthy measured level becomes available.
Inject a **manual inflow** into the basin. Registered as a predicted flow under the synthetic child `manual-qin` at position `in`. Useful when no physical inflow sensor is wired but the inflow is known externally (e.g. fed from a sewer model).
### `Qd`
```json
{ "topic": "Qd", "payload": 75 }
```
Forward a manual demand to every child aggregator (MGC first, then any direct pumps). **Only honoured when `config.control.mode === 'manual'`** — in any other mode the command is logged and discarded. Mirrors how `rotatingMachine` gates commands behind its mode field. The interpretation of the number depends on the child's scaling (`absolute` = m³/h, `normalized` = 0–100 %).
### `registerChild`
Internal. Child nodes (measurements, rotatingMachines, machineGroupControls, nested pumpingStations) emit this on their Port 2 a few hundred ms after deploy. The station resolves the Node-RED node id back to the source object and registers it via `childRegistrationUtils`.
## Output ports
### Port 0 — process data
Delta-compressed payload (only changed fields per tick). Keys follow the standard 4-segment format `<type>.<variant>.<position>.<childId>` plus a handful of top-level state fields merged in by `getOutput()`:
| Key | Meaning |
|---|---|
| `volume.predicted.atequipment.default` | Running predicted volume from the flow integrator (m³). |
| `volume.measured.atequipment.default` | Volume derived from a `measured` level sensor (m³). |
| `percControl` | Last demand (0–100+ %) forwarded to the machine group during level-based control. |
Consumers must cache and merge deltas — the example dashboard flows include a reusable function node that does exactly this.
### Port 1 — dbase (InfluxDB)
Line-protocol payload for the `telemetry` bucket. Tags stay low-cardinality (station name, asset type); fields carry the numeric state. See [EVOLV — InfluxDB Schema Design](https://gitea.wbd-rd.nl/RnD/EVOLV/src/branch/main/wiki/concepts/influxdb-schema-design.md).
### Port 2 — parent
`{ topic: "registerChild", payload: <this-node-id>, positionVsParent, distance }` — fired once ~100 ms after deploy so an upstream cascade can discover this station. Nested stations use this to register with an outer `pumpingStation` parent.
The basin is modelled as a rectangular prism with constant cross-section. Everything derives from `volume = level × surfaceArea`, with every level measured upward from the basin floor.
*Editable source: [`diagrams/basin-model.drawio.svg`](diagrams/basin-model.drawio.svg) (drag into draw.io; the SVG embeds the editable source). See [`diagrams/README.md`](diagrams/README.md) for the edit-and-export workflow.*
`startLevel` is deliberately not part of this generic basin diagram. It belongs to a control mode. For the current level-linear mode, see [`diagrams/modes/basin-mode-level-linear.drawio.svg`](diagrams/modes/basin-mode-level-linear.drawio.svg).
The pipe labels are intentional:
-`inflowLevel` is the bottom/invert of the incoming sewer pipe.
-`outflowLevel` is the top of the pump-suction/outlet pipe.
This avoids hiding hydraulic consequences behind ambiguous pipe-centre elevations. Pipe diameters are part of the model contract so later versions can derive pipe centre/crown/invert where needed.
`dryRunLevel` and `highVolumeSafetyLevel` are derived safety points. They provide margin before the two hard physical conditions:
- Actual dry-run risk is at or below the pumpable lower hydraulic reference.
- Actual overflowing is the boolean condition `level >= overflowLevel`.
The high-volume safety point exists so the station can still react before the basin is physically spilling. Once `overflowLevel` is reached, the model should report overflowing rather than treating that point as a controllable threshold.
**minHeightBasedOn** — which pipe defines `minVol`, the operational floor used for the initial seed, the dry-run trigger, and the 0 % point of the fill percentage:
The rectangular approximation is acceptable for this node's first basin model because operational level is always in metres from the basin floor, while calculated m³ can tolerate small shape errors. A later upgrade can replace `volume = level × surfaceArea` with a level-volume curve for benching, sumps, sediment/dead zones, and irregular wet-well geometry.
Both **measured** and **predicted** variants are always computed and stored, regardless of which one drives control. The active source surfaces on Port 0 as `flowSource`, so operators can watch sensor drift (measured diverges from predicted), validate the volume integrator, and diagnose "which source was active when X happened?".
The inflow / outflow alias map is deliberately wide so measurements (`upstream`/`downstream`) and predicted-flow subscriptions (`in`/`out`) both feed the same aggregator:
The `pumpingStation` supports multiple control modes. Each mode is a **policy that maps basin state to demand (0-100 %)**. `levelbased` uses `minLevel`, `startLevel`, and `maxLevel`; other modes may use different thresholds or compute them dynamically.
The basin model owns the shared physical and safety references: pipe elevations, `dryRunLevel`, `highVolumeSafetyLevel`, and `overflowLevel`. `startLevel` is mode-specific and is documented with the mode diagrams, not the generic basin drawing.
Every mode gets its own page under [`modes/`](modes/README.md) with a consistent layout (inputs, threshold policy, demand formula, edge cases) so they can be compared side-by-side. Currently:
`_safetyController` runs **before**`_controlLogic` every tick. Two rules, deliberately asymmetric — *dry-run protects the pumps from running themselves into air*, *high-volume protection tries to preserve distance to actual overflow*.
> ⚠️ **Known limitation — gravity-sewer context.** The "upstream STOP" action only makes sense in a **cascaded** station layout where the upstream equipment is an EVOLV-controllable pump or station. In a conventional wastewater wet-well the inflow is gravity-fed from the municipal sewer and **cannot be stopped** — attempting to would back up toilets. For that case the correct response at the high-volume safety point is to alarm early and keep downstream pumps at maximum demand. If `level >= overflowLevel`, the station should report actual overflowing as a boolean and, later, estimate/log spill over the weir for compliance reporting. The current code fires `execSequence: shutdown` on upstream children regardless of what they are; that should be gated on "is the upstream actually controllable?" and supplemented with overflow-rate tracking. Tracked as follow-up work.
A missing volume reading is treated as a hard fault: every direct machine is sent `execSequence: shutdown` and `safetyControllerActive` latches. Calibrate predicted volume (`calibratePredictedVolume`) or wire a level measurement to recover.
## Registration — which children count as flow?
`_registerPredictedFlowChild` subscribes only to the *highest-level aggregator* to prevent double-counting.
```
Without MGC: With MGC:
[ PumpingStation ] [ PumpingStation ]
│ │ │ │
│ │ │ [ MGC ]
│ │ │ │ │ │
● ● ● ● ● ●
(each pump subscribed (only MGC is subscribed;
directly) MGC aggregates its pumps)
N flow subscriptions. 1 flow subscription.
Risk: double-count if an Pumps' flow is already
MGC is added later. inside the MGC total.
```
Measurement children register separately via `_registerMeasurementChild` and feed the `measured` variant — they never collide with the predicted-flow subscription. Nested `pumpingStation` children are always subscribed and expose their net flow at the parent's position.
## Node status badge
Updated every second by `_updateNodeStatus` in `nodeClass.js`:
The canonical end-to-end demo lives in the EVOLV superproject at [`examples/pumpingstation-3pumps-dashboard/`](https://gitea.wbd-rd.nl/RnD/EVOLV/src/branch/main/examples/pumpingstation-3pumps-dashboard). It wires three `rotatingMachine` pumps beneath an MGC beneath a `pumpingStation`, with the dashboard layout rule set (see the [EVOLV flow-layout rules](https://gitea.wbd-rd.nl/RnD/EVOLV/src/branch/main/.claude/rules/node-red-flow-layout.md)) — a useful template for any new station.
| `fill %` exceeds 100 % or is negative | Basin geometry inconsistent — e.g. `overflowLevel > basinHeight`, or `outflowLevel > inflowLevel`. | Cross-check `0 < outflowLevel < inflowLevel < overflowLevel <= basinHeight` in the editor. |
| Pumps never start in `levelbased` | Level is stuck in the DEAD ZONE between `minLevel` and `startLevel`, or `startLevel == maxLevel` so the scaling range collapses. | Widen the mode control band. In sewer-gravity cases, `startLevel` is normally below `inflowLevel` so the station starts draining before the incoming sewer pipe is hydraulically affected. |
| "No volume data available to safe guard system; shutting down all machines." in logs | No measured level, predicted volume not calibrated, and no inflow/outflow samples yet. | Issue `calibratePredictedVolume` (or `calibratePredictedLevel`) once at startup, or wire a level sensor. |
| `flowSource: null` and `direction: 'steady'` forever | Every flow / level signal falls inside the dead-band (default `1e-4 m³/s`). | Confirm flows are non-zero, or lower `config.general.flowThreshold` for a small-scale demo. |
| `Qd` ignored | Station is not in `manual` mode. | Send `{ topic: 'changemode', payload: 'manual' }` first, or fall back to level-based control. |
| Pumps keep running during overfill | Intended — overfill safety only stops **upstream** equipment; downstream pumps must drain. | To override, switch to `manual` and set `Qd = 0`, or issue an emergency-stop at the MGC. |
| Predicted volume drifts away from measured | Flow integrator has no reference — flows might have the wrong sign, or `unit` is mis-declared. | Call `calibratePredictedVolume` periodically from a measured level. |
Then in Node-RED: **Import ▸ Examples ▸ EVOLV ▸ pumpingStation** (or open `examples/pumpingstation-3pumps-dashboard/flow.json`).
## Testing
```bash
cd nodes/pumpingStation
npm test
```
Unit tests live in `test/specificClass.test.js` — construction, basin derivation, measurement registration, net-flow selection, safety interlocks, and calibration.
- [EVOLV — Group Optimization](https://gitea.wbd-rd.nl/RnD/EVOLV/src/branch/main/wiki/architecture/group-optimization.md) — pump-group scheduling theory.
- [EVOLV — flow-layout rules](https://gitea.wbd-rd.nl/RnD/EVOLV/src/branch/main/.claude/rules/node-red-flow-layout.md) — the lane / group / channel layout rules used by the demo flows.
