Plumbing Backflow Preventer Pressure Drop Calculator
Read actual matched backflow-device measured flow/drop curve and signed resulting downstream pressure; no generic valve Cv alias, extrapolation, contamination prevention or device certification.
Description
A matched backflow-device curve estimates drop at observed flows.
A matched backflow-device curve estimates drop at observed flows. Gauge downstream pressure can remain signed.1
The returned values include Caller interpolated backflow drops kpa, Modeled downstream gauge kpa. The How section below explains the calculation, input rules and interpretation.
When to use Plumbing Backflow Preventer Pressure Drop Calculator
Use Plumbing Backflow Preventer Pressure Drop Calculator when you need to evaluate the supplied records under the calculation and evidence rules below. No extrapolation, contamination-prevention guarantee or device certification 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 Backflow Preventer Pressure Drop 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 callerMatchedBackflowFlowKnotsLitersMinute, callerMeasuredBackflowDropKnotsKpa, observedQueryFlowsLitersMinute, observedUpstreamGaugeKpa using the field table and calculation rules, then run the tool.
- Read callerInterpolatedBackflowDropsKpa, modeledDownstreamGaugeKpa. 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 |
|---|---|---|---|
| callerMatchedBackflowFlowKnotsLitersMinute | Caller matched backflow flow knots liters minute | list of number | Required |
| callerMeasuredBackflowDropKnotsKpa | Caller measured backflow drop knots kpa | list of number | Required |
| observedQueryFlowsLitersMinute | Observed query flows liters minute | list of number | Required |
| observedUpstreamGaugeKpa | Observed upstream gauge kpa | number | Required |
Enter nonnegative flow knots, drop knots and query flows plus nonnegative upstream gauge kPa. For each query require aligned calibration lists with at least two strictly increasing knots and an inclusive in-range query. Return drops and signed downstream pressures; an empty query list performs no interpolation.
drop_i=linearInterpolation(flowKnots,dropKnots,query_i); downstreamGauge_i=upstreamGauge−drop_i Units, indexing, boundary conditions and exceptional cases are defined in the calculation rules above.
| Output field | Meaning | Value type |
|---|---|---|
| callerInterpolatedBackflowDropsKpa | Caller interpolated backflow drops kpa | list of number |
| modeledDownstreamGaugeKpa | Modeled downstream gauge kpa | list of number |
{
"input": {
"callerMatchedBackflowFlowKnotsLitersMinute": [
0,
10,
20
],
"callerMeasuredBackflowDropKnotsKpa": [
0,
5,
15
],
"observedQueryFlowsLitersMinute": [
5,
15
],
"observedUpstreamGaugeKpa": 100
},
"output": {
"callerInterpolatedBackflowDropsKpa": [
2.5,
10
],
"modeledDownstreamGaugeKpa": [
97.5,
90
]
}
}Limitations and assumptions
No extrapolation, contamination-prevention guarantee or device certification 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 Hydronic Zone Valve Cv Calculator: Cv uses US gallons per minute and psi with fluid specific gravity. It differs from SI Kv and dimensionless valve authority. For a complementary task, use Plumbing Gas Pipe Pressure Drop Calculator: Measured gas-route pressure drops add before subtraction from absolute upstream pressure. Absolute downstream pressure must remain positive.
References
Similar or alternative tools
- Plumbing Hydronic Zone Valve Cv Calculator
Cv uses US gallons per minute and psi with fluid specific gravity. It differs from SI Kv and dimensionless valve authority.
- Plumbing Gas Pipe Pressure Drop Calculator
Measured gas-route pressure drops add before subtraction from absolute upstream pressure. Absolute downstream pressure must remain positive.