Fault Tree OR Gate Calculator
ORgate failure1−product(1−p), independently mutually independent events only; common cause/overlap external. Actual independently established compatible SI units/model context; conditional arithmetic, not code compliance, engineering design or safe operation approval.
Description
An OR-gate probability can combine event probabilities by the complement-product rule when mutual independence holds.
An OR-gate probability can combine event probabilities by the complement-product rule when mutual independence holds.1
This tool evaluates that supplied assumption without modeling common causes or an entire fault tree.
When to use Fault Tree OR Gate Calculator
Use this tool to evaluate that supplied assumption without modeling common causes or an entire fault tree.
How to use Fault Tree OR Gate Calculator and how it works
- Prepare independentEventProbabilities, with the units, conventions and assumptions below.
- Enter the required fields and run Fault Tree OR Gate Calculator.
- Read result.value using the output definitions below.
- Correct any rejected inputs and rerun; interpret the result within the stated model and its assumptions.
| Input field | Meaning | Value type | Requirement |
|---|---|---|---|
| independentEventProbabilities | Independent Event Probabilities. Use the units and matching context stated in the calculation below. | array of number | Required; other constraints below |
Supply a nonempty array of independent basic-event probabilities, each from zero to one inclusive. Multiply their complements and return one minus that product. Independence is an external assumption; common-cause or conditional dependencies are not modeled.
ORprobability=1-product(1-p_i) Apply the input ordering, units and branch conditions stated above.
| Output field | Meaning | Value type |
|---|---|---|
| result | Object containing the calculated or selected fields below. | object |
| result.value | Dimensionless OR-gate probability under the independent-event assumption. | number |
{
"input": {
"independentEventProbabilities": [
0.5,
0.2
]
},
"output": {
"result": {
"value": 0.6
}
}
}Limitations and assumptions
The calculation uses the supplied observations and model inputs. It does not collect measurements, select a reference population or coefficient, or establish that the model applies to the actual case. The stated branch conditions and output units remain part of the result.
All fields require explicit values. Unexpected fields, wrong types, nonfinite numbers and sparse arrays are rejected. Alignment, bounds and supported-token rules are explained above; extremely large inputs or nonfinite results can also fail. Input errors differ from successful false comparisons, unavailable-domain flags and empty match lists.
Alternative or Complementary methods
Use Risk Priority Number Calculator for a complementary operation: An FMEA risk priority number multiplies ordinal severity, occurrence and detection codes under a chosen scoring convention.
Use Fault Tree AND Gate Calculator for a complementary operation: An AND-gate probability equals a product only when the supplied event model supports mutual independence.
References
-
Fault Tree OR Gate Calculator — tool.io
Similar or alternative tools
- Risk Priority Number Calculator
An FMEA risk priority number multiplies ordinal severity, occurrence and detection codes under a chosen scoring convention.
- Fault Tree AND Gate Calculator
An AND-gate probability equals a product only when the supplied event model supports mutual independence.