System Pressure/Flow Balance

Fluid & Pressure

Compare measured ΔP to calculated straight-pipe plus known K losses.

App id: FLUID-18. Reference version 1.0.

How to fill it

Fill the inputs. The tool shows the outputs.

On the tool screen, Calc is the working sheet. Presets stores values you reuse. Reference is the formula, assumptions, and provenance below.

Formula

ΔP_calc = f(L/D)(ρv²/2) + K ρv²/2

Inputs

Name	Unit
Upstream pressure (camera)	`kPa`
Downstream pressure (camera)	`kPa`
Volumetric flow (camera)	`m3/s`
Inside diameter	`mm`
Pipe length	`m`
Density	`kg/m3`
Dynamic viscosity	`Pa-s`
Absolute roughness (optional)	`mm`
Fitting K (sum) (optional)	`1`

Outputs

Name	Unit
Unexplained ΔP (hero result)	`kPa`
Measured ΔP	`kPa`
Calculated ΔP	`kPa`
Straight-pipe loss	`kPa`
Minor loss	`kPa`
Mean velocity	`m/s`
Reynolds number	`1`
Darcy friction factor	`1`

Diagnose

Observations are context. They do not pass or fail a structure. See Diagnose.

Screening bands in the app: Laminar · Transitional · Turbulent.

When	Observation	Severity
`Mean velocity < 0.3`	Low velocity	info
`Mean velocity > 5`	High velocity	caution
`Mean velocity > 3`	Elevated velocity	info
`Reynolds number < 2300`	Laminar	info
`Reynolds number ≤ 4000`	Transitional	caution
`Reynolds number > 4000`	Turbulent	info
`ratio > 1.25`	Measured loss exceeds calculated loss	caution
`ratio < 0.75`	Measured loss below calculated loss	caution
`ratio ≥ 0.75`	Loss broadly consistent	info

Assumptions

Elevation change is not included — use the pipeline gradient tool when profile matters.
Leave K blank when fittings are unknown.

Provenance

Field comparison of measured ΔP to Darcy–Weisbach plus a lumped K.