Pipeline Pressure Gradient

Fluid & Pressure

Compare observed pipeline ΔP to friction and elevation contributions.

App id: FLUID-22. 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_obs = ΔP_friction + ρ g Δz + residual

Inputs

Name	Unit
Upstream pressure (camera)	`kPa`
Downstream pressure (camera)	`kPa`
Segment length	`m`
Inside diameter	`mm`
Volumetric flow	`m3/s`
Density	`kg/m3`
Dynamic viscosity	`Pa-s`
Absolute roughness (optional)	`mm`
Elevation change (down − up) (optional)	`m`
Gravity (optional)	`m/s2`

Outputs

Name	Unit
Unexplained ΔP (hero result)	`kPa`
Measured ΔP	`kPa`
Friction + elevation ΔP	`kPa`
Observed pressure gradient	`Pa/m`
Friction gradient	`Pa/m`
Elevation contribution	`kPa`
Mean velocity	`m/s`
Reynolds number	`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 downstream elevation minus upstream elevation.
Positive elevation change raises downstream hydrostatic pressure (uphill as positive Δz).

Provenance

Segment energy balance: friction plus hydrostatic elevation, remainder unexplained.