Plumbing Roof Drain Size Calculator

Screen actual primary roof drain demand against independently verified matched head/slope candidate capacities; no universal rainfall, pipe code table or flood protection approval.

Description

Roof-drain selection needs capacities rated at matched head and slope.

Roof-drain selection needs capacities rated at matched head and slope. Comparing primary runoff demand leaves each candidate’s margin visible.^[1]

The returned values include Caller compatible candidate ids, Signed candidate capacity margins liters second. The How section below explains the calculation, input rules and interpretation.

When to use Plumbing Roof Drain Size Calculator

Use Plumbing Roof Drain Size Calculator when you need to evaluate the supplied records under the calculation and evidence rules below. No rainfall estimate, overflow design or flood/code approval is supplied.

Prepare measured flows, pressures, temperatures or inventories with consistent units. For catalog tools, use independently verified capacities at the stated operating conditions and supply the explicit design demand.

How to use Plumbing Roof Drain Size Calculator and understand its results

Prepare measured flows, pressures, temperatures or inventories with consistent units. For catalog tools, use independently verified capacities at the stated operating conditions and supply the explicit design demand.
Enter callerRoofDrainIds, callerMatchedRoofDrainCapacityLitersSecond, observedDesignRoofRunoffLitersSecond using the field table and calculation rules, then run the tool.
Read callerCompatibleCandidateIds, signedCandidateCapacityMarginsLitersSecond. The explanation below defines the units, signs, ordering and any flags or placeholder values.
If the tool reports an input issue, correct the values and run it again. Apply the stated assumptions when interpreting a successfully returned result.

Input field	Meaning	Value type; see rules below	Requirement
callerRoofDrainIds	Caller roof drain ids	list of string	Required
callerMatchedRoofDrainCapacityLitersSecond	Caller matched roof drain capacity liters second	list of number	Required
observedDesignRoofRunoffLitersSecond	Observed design roof runoff liters second	number	Required

Enter aligned nonempty unique nonblank drain IDs and nonnegative capacities, plus nonnegative design runoff. Return every adequate ID in order and all signed margins.

margin=capacity−runoff; eligible=margin≥0

Units, indexing, boundary conditions and exceptional cases are defined in the calculation rules above.

Output field	Meaning	Value type
callerCompatibleCandidateIds	Caller compatible candidate ids	list of string
signedCandidateCapacityMarginsLitersSecond	Signed candidate capacity margins liters second	list of number

json

{
  "input": {
    "callerRoofDrainIds": [
      "a",
      "b",
      "c"
    ],
    "callerMatchedRoofDrainCapacityLitersSecond": [
      5,
      10,
      20
    ],
    "observedDesignRoofRunoffLitersSecond": 8
  },
  "output": {
    "callerCompatibleCandidateIds": [
      "b",
      "c"
    ],
    "signedCandidateCapacityMarginsLitersSecond": [
      -3,
      2,
      12
    ]
  }
}

Limitations and assumptions

No rainfall estimate, overflow design or flood/code approval is supplied.

Numeric inputs, where present, must be finite. Follow the calculation-specific rules for overflow, underflow and exceptional cases. Numeric lists are limited to 10,000 entries; string lists to 128 strings of at most 128 characters each. The rules above may impose smaller limits. Missing required fields, extra fields, wrong value types and violations of the calculation rules are input errors.

Alternative or Complementary methods

Use Plumbing Storm Drain Size Calculator: Storm-drain capacities depend on matched slope and hydraulic conditions. A caller catalog screens all candidates against design flow. For a complementary task, use Plumbing Catch Basin Size Calculator: Catch-basin volume combines a retention budget with reserved sediment storage. Usable fraction converts that budget to nominal volume.

References

Plumbing Roof Drain Size Calculator — tool.io

Similar or alternative tools

Plumbing Storm Drain Size Calculator
Storm-drain capacities depend on matched slope and hydraulic conditions. A caller catalog screens all candidates against design flow.
Plumbing Catch Basin Size Calculator
Catch-basin volume combines a retention budget with reserved sediment storage. Usable fraction converts that budget to nominal volume.