# valve

> **Reflects code as of `e27135b` · regenerated `2026-05-11` via `npm run wiki:all`**
> If this banner is stale, the page may be out of date. Treat as informative, not authoritative.

## 1. What this node is

**valve** models a single actuated throttling valve at the S88 Equipment Module level. It loads a supplier Kv-vs-position characteristic curve, drives an FSM for open/close move sequences (using `accelerating`/`decelerating` states shared with `rotatingMachine`), and recomputes pressure drop from flow + Kv via a hydraulic model. Used standalone or as a child of `valveGroupControl`.

## 2. Position in the platform

```mermaid
flowchart LR
    vgc[valveGroupControl<br/>Unit]:::unit -->|set.position| this[valve<br/>Equipment]:::equip
    src["machine / MGC / PS<br/>(upstream source)"]:::unit -->|child.register| this
    meas[measurement<br/>type=pressure / flow]:::ctrl -.->|data| this
    this -->|child.register Port 2| vgc
    this -->|evt.deltaPChange| vgc
    this -->|evt.fluidCompatibilityChange| vgc
    classDef unit fill:#50a8d9,color:#000
    classDef equip fill:#86bbdd,color:#000
    classDef ctrl fill:#a9daee,color:#000
```

S88 colours: Unit `#50a8d9`, Equipment `#86bbdd`, Control Module `#a9daee`. Source: `.claude/rules/node-red-flow-layout.md`.

## 3. Capability matrix

| Capability | Status | Notes |
|---|---|---|
| Predicts deltaP from flow + Kv | ✅ | Hydraulic model picks liquid vs gas formula per `serviceType`. |
| Loads supplier curve by model name | ✅ | `asset.model` resolved through `loadModel`; inline `valveCurve` override supported. |
| Position move FSM | ✅ | `accelerating` / `decelerating` states with interruptible setpoints; `moveTo` uses shared state machine. |
| Startup / shutdown sequences | ✅ | Pre-shutdown ramps valve to position 0 before executing stop sequence. |
| Emergency-stop sequence | ✅ | `cmd.estop` → `emergencystop → off` sequence. |
| Fluid-contract aggregation | ✅ | Tracks upstream service type via registered sources through `FluidCompatibility`. |
| Gas-choke detection | ⚠️ | Hard cap at `gasChokedRatioLimit`; surfaced in `hydraulicDiagnostics`. |
| Multi-parent registration | ⚠️ | Allowed but not exercised in production tests. |

## 4. Code map

```mermaid
flowchart TB
    subgraph nodeRED["nodeClass.js — adapter (BaseNodeAdapter)"]
        nc["buildDomainConfig()<br/>static DomainClass=Valve, commands<br/>tickInterval=null (event-driven)"]
    end
    subgraph domain["specificClass.js — orchestrator (BaseDomain)"]
        sc["Valve.configure()<br/>wires concern modules<br/>overrides registerChild → FluidCompatibility"]
    end
    subgraph concerns["src/ concern modules"]
        state["state/<br/>stateBindings → positionChange"]
        fluid["fluid/<br/>FluidCompatibility"]
        curve["curve/<br/>SupplierCurvePredictor"]
        meas["measurement/<br/>MeasurementRouter + FORMULA_UNITS"]
        flow["flow/<br/>FlowController (setpoint, sequences)"]
        io["io/<br/>buildOutput + buildStatusBadge"]
        hyd["hydraulicModel.js<br/>ValveHydraulicModel"]
    end
    nc --> sc
    sc --> state
    sc --> fluid
    sc --> curve
    sc --> meas
    sc --> flow
    sc --> io
    sc --> hyd
```

| Module | Owns | Read first if you're changing… |
|---|---|---|
| `state/` | Bindings from state-machine `positionChange` → `updatePosition()` | Move-finished triggers, position callbacks. |
| `fluid/` | Service-type compatibility, contract aggregation | Gas-vs-liquid mismatch warnings, upstream fluid tracking. |
| `curve/` | Supplier Kv curve load + interpolation | Curve fitting, model selection, density keys. |
| `measurement/` | Pressure/flow routing + deltaP recompute | What triggers a recalc, measurement container writes. |
| `flow/` | Sequence + setpoint execution, mode validation | Startup / shutdown / move semantics, allowed-source checks. |
| `io/` | Port-0 output shape + status badge | What lands on the wire each tick. |
| `hydraulicModel.js` | Liquid + gas deltaP formulas, choke detection | Hydraulic calculation errors, choke ratio behaviour. |

## 5. Topic contract

> **Auto-generated** from `src/commands/index.js`. Do NOT hand-edit between the markers. Re-run `npm run wiki:contract`.

<!-- BEGIN AUTOGEN: topic-contract -->

| Canonical topic | Aliases | Payload | Unit | Effect |
|---|---|---|---|---|
| `set.mode` | `setMode` | `string` | — | Switch the valve between auto / manual control modes. |
| `cmd.startup` | _(none)_ | `any` | — | Initiate the valve startup sequence. |
| `cmd.shutdown` | _(none)_ | `any` | — | Initiate the valve shutdown sequence. |
| `cmd.estop` | `emergencystop`, `emergencyStop` | `any` | — | Trigger an emergency stop on the valve. |
| `execSequence` | _(none)_ | `object` | — | Legacy umbrella that demuxes payload.action to startup / shutdown / estop. |
| `set.position` | `execMovement` | `object` | — | Move the valve to a control-% position via execMovement. |
| `data.flow` | `updateFlow` | `object` | — | Push a measured flow into the valve (variant + position + unit). |
| `query.curve` | `showcurve` | `any` | — | Return the valve characteristic curve on the reply port. |
| `child.register` | `registerChild` | `string` | — | Register a child measurement with this valve. |

<!-- END AUTOGEN: topic-contract -->

## 6. Child registration

valve overrides `BaseDomain.registerChild` with `FluidCompatibility.registerChild`. Upstream sources feed the fluid-contract aggregator; measurement children attach through the standard measurement handshake and land in `MeasurementRouter`.

```mermaid
flowchart LR
    subgraph kids["accepted children (softwareType)"]
        src["machine / rotatingmachine<br/>machinegroup / pumpingstation<br/>valvegroupcontrol"]:::unit
        m["measurement<br/>type=pressure or flow"]:::ctrl
    end
    src -->|getFluidContract| fluid[FluidCompatibility<br/>aggregates serviceType]
    m   -->|"&lt;type&gt;.measured.&lt;position&gt;"| router[MeasurementRouter<br/>updatePressure / updateFlow]
    router --> deltaP[updateDeltaP<br/>writes pressure.predicted.delta]
    fluid --> evt1["evt.fluidCompatibilityChange<br/>evt.fluidContractChange"]
    deltaP --> evt2[evt.deltaPChange]
    classDef unit fill:#50a8d9,color:#000
    classDef ctrl fill:#a9daee,color:#000
```

| softwareType | onRegister side-effect | Subscribed events |
|---|---|---|
| `machine` / `rotatingmachine` | Stored as upstream source; reads `getFluidContract()` or defaults to `liquid`. | `fluidContractChange` |
| `machinegroup` / `machinegroupcontrol` | Same; recomputes aggregate service type. | `fluidContractChange` |
| `pumpingstation` | Same. | `fluidContractChange` |
| `valvegroupcontrol` | Same. | `fluidContractChange` |
| `measurement` | Routed via measurement handshake; values land in `MeasurementContainer`. | `<type>.measured.<position>` |

## 7. Lifecycle — what one event does

```mermaid
sequenceDiagram
    participant parent as valveGroupControl
    participant valve as valve
    participant fsm as state FSM
    participant hyd as hydraulicModel
    participant out as Port-0

    parent->>valve: set.position { setpoint: 60 }
    valve->>fsm: moveTo(60)
    fsm-->>fsm: operational → accelerating
    fsm-->>valve: positionChange ticks (stateBindings)
    valve->>valve: predictKv(position)
    valve->>hyd: calculateDeltaPMbar(q, kv, downP, rho, T)
    hyd-->>valve: { deltaPMbar, diagnostics }
    valve->>valve: write pressure.predicted.delta
    valve->>parent: emitter.emit('deltaPChange', deltaP)
    valve->>out: msg { topic, payload (delta-compressed) }
    fsm-->>fsm: accelerating → operational (setpoint reached)
```

## 8. Data model — `getOutput()`

What lands on Port 0. Composed in `io/output.buildOutput`, then delta-compressed by `outputUtils.formatMsg`.

<!-- BEGIN AUTOGEN: data-model -->

| Key | Type | Unit | Sample |
|---|---|---|---|
| `state` | string | — | `"operational"` |
| `percentageOpen` | number | % | `0` |
| `moveTimeleft` | number | s | `0` |
| `mode` | string | — | `"auto"` |
| `downstream_predicted_flow` | number | m3/h | `0` |
| `downstream_measured_flow` | number | m3/h | _(emitted when measurement child present)_ |
| `downstream_predicted_pressure` | number | mbar | _(emitted when upstream pressure present)_ |
| `downstream_measured_pressure` | number | mbar | _(emitted when measurement child present)_ |
| `delta_predicted_pressure` | number | mbar | `0` |

<!-- END AUTOGEN: data-model -->

Measurement keys follow the legacy `<position>_<variant>_<type>` shape (e.g. `downstream_predicted_flow`, `delta_predicted_pressure`). Only keys with finite values are emitted — consumers must cache and merge (delta-compression is active).

## 9. Configuration — editor form ↔ config keys

```mermaid
flowchart TB
    subgraph editor["Node-RED editor form"]
        f1[Reaction Speed]
        f2[Asset model / supplier / category]
        f3[Service type]
        f4[Fluid density / temperature K]
        f5[Gas choke ratio limit]
        f6[Startup / warmup / shutdown / cooldown times]
        f7[Log level / enableLog]
        f8[positionVsParent]
    end
    subgraph config["Domain config slice"]
        c1["movement.speed (stateConfig)"]
        c2[asset.model]
        c3["runtimeOptions.serviceType → hydraulicModel"]
        c4["runtimeOptions.fluidDensity / fluidTemperatureK"]
        c5["runtimeOptions.gasChokedRatioLimit"]
        c6["stateConfig.time.starting / warmingup / stopping / coolingdown"]
        c7["general.logging.enabled / logLevel"]
        c8["functionality.positionVsParent → Port-2 registration"]
    end
    f1 --> c1
    f2 --> c2
    f3 --> c3
    f4 --> c4
    f5 --> c5
    f6 --> c6
    f7 --> c7
    f8 --> c8
```

| Form field | Config path | Default | Range / type | Where used |
|---|---|---|---|---|
| Reaction Speed | `movement.speed` (stateConfig) | `1` | > 0 (%/s) | `MovementManager` — sets rate of position change |
| Asset model | `asset.model` | `'Unknown'` | string | `SupplierCurvePredictor` — selects Kv curve dataset |
| Service type | `runtimeOptions.serviceType` | `null` (from asset) | `'gas'` / `'liquid'` | `ValveHydraulicModel` formula selection |
| Fluid density | `runtimeOptions.fluidDensity` | model default | > 0 (kg/m³) | liquid hydraulic formula |
| Fluid temperature | `runtimeOptions.fluidTemperatureK` | model default | > 0 (K) | gas hydraulic formula |
| Gas choke limit | `runtimeOptions.gasChokedRatioLimit` | per asset | 0–1 | gas choke cap in `ValveHydraulicModel` |
| Startup time | `stateConfig.time.starting` | `10` s | > 0 (s) | `StateManager` transition timer |
| Warmup time | `stateConfig.time.warmingup` | `5` s | > 0 (s) | `StateManager` protected transition |
| Shutdown time | `stateConfig.time.stopping` | `5` s | > 0 (s) | `StateManager` transition timer |
| Cooldown time | `stateConfig.time.coolingdown` | `10` s | > 0 (s) | `StateManager` transition timer |
| Mode | `mode.current` | `'auto'` | `auto` / `virtualControl` / `fysicalControl` / `maintenance` | `FlowController.isValidSourceForMode` |
| Log level | `general.logging.logLevel` | `'info'` | enum | structured logger |
| positionVsParent | `functionality.positionVsParent` | `'atEquipment'` | enum | Port-2 registration message to parent |

## 10. State chart

```mermaid
stateDiagram-v2
    [*] --> off
    off --> idle : cmd.startup (boot sequence)
    off --> emergencystop : cmd.estop
    off --> maintenance : set.mode=maintenance

    idle --> starting : cmd.startup
    idle --> off : (direct transition)
    idle --> emergencystop : cmd.estop
    idle --> maintenance : set.mode=maintenance

    starting --> warmingup : timed (starting duration)
    starting --> emergencystop : cmd.estop

    warmingup --> operational : timed (warmup duration) [protected — cannot abort]
    warmingup --> emergencystop : cmd.estop

    operational --> accelerating : set.position > current
    operational --> decelerating : set.position < current
    operational --> stopping : cmd.shutdown
    operational --> emergencystop : cmd.estop

    accelerating --> operational : setpoint reached
    accelerating --> emergencystop : cmd.estop

    decelerating --> operational : setpoint reached
    decelerating --> emergencystop : cmd.estop

    stopping --> coolingdown : timed (stopping duration)
    stopping --> idle : (direct)
    stopping --> emergencystop : cmd.estop

    coolingdown --> idle : timed (cooldown duration) [protected — cannot abort]
    coolingdown --> off : (direct)
    coolingdown --> emergencystop : cmd.estop

    emergencystop --> idle : cmd.reset / sequence
    emergencystop --> off : cmd.reset / sequence
    emergencystop --> maintenance : (allowed)

    maintenance --> idle : manual reset
    maintenance --> off : manual reset
```

**Key valve-specific behaviours:**

- `accelerating` = position moving up; `decelerating` = position moving down. Both fire `positionChange` ticks. The valve's `stateBindings` hooks these to `updatePosition()` → Kv lookup → deltaP recompute.
- `warmingup` and `coolingdown` are **protected** — the abort signal is disabled; these phases cannot be interrupted.
- `cmd.shutdown` from `operational` first ramps the valve to position 0 (via `FlowController.executeSequence('shutdown')`), then transitions `stopping → coolingdown → idle`.
- `cmd.estop` triggers `emergencystop → off` regardless of current state (except from within protected transitions).
- Default sequences: `startup` = `[starting, warmingup, operational]`; `boot` = `[idle, starting, warmingup, operational]`; `emergencystop` = `[emergencystop, off]`.

## 11. Examples

| Tier | File | What it shows | Mandatory? |
|---|---|---|---|
| Basic | `examples/basic.flow.json` | Inject `set.position` + minimal wiring, no parent | ✅ |
| Integration | `examples/integration.flow.json` | valve + VGC + upstream measurement source | ✅ |
| Edge | `examples/edge.flow.json` | Edge-case inputs (gas, choke, estop, bad setpoints) | ⭕ optional |

Renamed example files (`01-Basic.flow.json`, `02-Integration.flow.json`, `03-Dashboard.flow.json`) will replace the above when produced. Screenshots under `wiki/_partial-screenshots/valve/`. Docker compose snippet under `examples/README.md`.

## 12. Debug recipes

| Symptom | First thing to check | Where to look |
|---|---|---|
| Status badge shows `⚠ no input` | Did any pressure / flow measurement register? Watch Port 2. | Debug tap on Port 2 |
| `delta_predicted_pressure` stuck at `0` | Is `kv > 0`? FSM may be in `off` / `idle` — valve is closed. | `state.getCurrentState()`, `percentageOpen` |
| Gas mismatch warning on status badge | `fluidCompatibility.status` is `mismatch` or `conflict`. | `getFluidCompatibility()` |
| `query.curve` returns empty curve | `asset.model` not found by `loadModel`; check `SupplierCurvePredictor.snapshot()`. | `SupplierCurvePredictor.snapshot()` |
| deltaP non-finite | Downstream gauge pressure absolute term ≤ 0, or choked ratio reached. | `hydraulicDiagnostics` in output |
| `set.position` has no effect | Check `currentMode` — source may not be in `mode.allowedSources[mode]`. | `FlowController.isValidSourceForMode` |
| FSM stuck in `accelerating` / `decelerating` | Movement was aborted but `_returnToOperationalOnAbort` was false. Send a new `set.position`. | `state.js` abort logic |

> Never ship `enableLog: 'debug'` in a demo — fills the container log within seconds and obscures real errors. Use only for live debugging.

## 13. When you would NOT use this node

- Use valve for a **throttling actuator** with a known Kv curve. For a fixed-restriction orifice (no actuator, no curve), model the deltaP externally.
- Don't use valve to model a **non-return / check valve** — no position control or FSM-driven actuation is exposed.
- Skip valve when an upstream source already provides flow directly and **no pressure-drop estimate is needed** — wire the source straight to the parent without inserting a valve.

## 14. Known limitations / current issues

| # | Issue | Tracked in |
|---|---|---|
| 1 | Gas-choke detection is a hard cap, not a smooth transition — chart traces show a step at the choked-ratio limit. | `hydraulicModel.js` |
| 2 | Multi-parent registration is allowed but not exercised in production tests. | `CONTRACT.md` — Children registered by this node |
| 3 | `set.position` move sequences are interruptible but tests cover happy-path only; abort-deadlock edge case documented separately. | `state.js` abort logic + `test/integration/` |
| 4 | `execSequence` (legacy umbrella topic) will be removed in Phase 7 — callers must migrate to `cmd.startup` / `cmd.shutdown` / `cmd.estop`. | `CONTRACT.md` — execSequence demux |