{
  "ran": "2026-10-13T05:22:45.703Z",
  "how": "kit/cistern.mjs stepped with dt = 0.02 s (explicit Euler) against closed forms. Torricelli outflow Q = Cd·a·sqrt(2gh) through the 2-inch flush valve seat while the flapper is open, through a leak area otherwise. Flapper closes when the level reaches closeLevel. Fill valve opens when the level drops by deadband below its set level and closes at it. Tank area is chosen in closed form so that one flush delivers flushVolume to the bowl, counting what the fill valve adds once the level has dropped by deadband.",
  "sources": {
    "setLevel": "Fluidmaster 400A instructions, PART# 4-743 Grev. 6 08/14: water level 1/2 inch below top of overflow pipe",
    "flushVolume": "10 CFR 430.32(q): 1.6 gal (6.0 L) per flush for gravity tank water closets made after 1994-01-01",
    "flapper": "US 2004/0172746 A1: air pocket keeps the flapper open until most of the water has left"
  },
  "assumptions": {
    "overflow_m": 0.18,
    "closeLevel_m": 0.03,
    "seatDiameter_m": 0.0508,
    "cd": 0.61,
    "fillFlow_L_per_min": 6,
    "deadband_m": 0.01,
    "leakArea_mm2": 2,
    "shortChainLeak": "10 x leakArea"
  },
  "derived": {
    "tankArea_m2": 0.04108,
    "flushSeconds": 3.78,
    "flushLitres": 6.004,
    "phantomPeriod_s": 193,
    "phantomMeasured_s": 193,
    "leak_L_per_day": 190.9,
    "shortChainLeak_L_per_day": 1909,
    "floatHighWaste_L_per_min": 6,
    "floatHighWaste_L_per_day": 8640
  },
  "ok": true
}