How does LOGOS calculate head loss and the operating point?

Head loss is calculated by Darcy-Weisbach with the friction factor from Colebrook-White (solved by the Serghides estimator). The operating point is found by bisection of the intersection between the system curve and the pump curve.

Does the result match my Excel spreadsheet?

Each routine is field-validated and built on standards (Darcy-Weisbach, Colebrook-White, IEC, ISO, API). The method is fully shown in the Word report, so you can audit every step against your own calculation.

Does LOGOS generate a calculation report?

Yes. Each calculation generates a Word (.docx) calculation report with the cited formulas and standards, ready to attach to the project and sign.

field-validated · standards-based and traceable

Hydraulic sizing with the precision of your spreadsheet — and the traceability it never had.

Size pumps, control valves, orifice plates and water hammer with head loss by Darcy-Weisbach — the rigor your spreadsheet always lacked, now with a calculation report in Word ready to sign.

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↓ the tool, solving a real case

▸ logos · pump sizing solved example

01 System data

Target flowm³/h 20.0 Discharge diametermm 60 Discharge lengthm 300 Static headm 15.5

method Darcy-Weisbach · Colebrook-White

02 Result

Operating point 16.3m³/h

Total head 30.6mca

Discharge head loss 14.8mca

Discharge velocity 1.60m/s

H (mca) Q (m³/h) →

system curve pump curve operating point

✓ field-validated, standards-based calculation Run your calculation →

17: verified calculation routines
8+: citable standards and methods
6: normative frameworks
.docx: report ready to sign

Your sizing spreadsheet was built by someone who left the company 6 years ago. Do you still trust it?

No trail

No versions, no record of which standard or pump catalog was used. When the calculation is challenged, there is no way to defend it.

Breaks when edited

One cell overwritten by mistake and the whole formula silently starts to lie. No one notices until the pump cavitates in the field.

No report

The document you sign off for the project you still assemble by hand, copying number by number. Hours lost, transcription errors.

From the system to the report, in three steps.

01
Enter the system

Fluid, piping, fittings and the pump curve. The same data you already gather in the spreadsheet — only validated on input.
02
Calculate with a standardized method

Operating point by bisection of the pump × system curve; head loss by Darcy-Weisbach. Transparent, never a black box.
03
Download the report in Word

A formatted calculation report, with cited formulas and standards — ready to attach to the project and sign with engineering responsibility.

What you size here.

All 17 calculation routines, already available — all free to use.

Pumping

Gravity

Multi-branch networks

Valves, plates and transients

The precision of expensive software. The price of a spreadsheet.

The same standardized calculation that engineering software costing thousands delivers — with nothing to install, no license, and a report ready to sign.

Feature	LOGOS	Excel spreadsheet	Engineering software
Price	Free to start	Free	Thousands per license
Calculation report in Word	✓	✕	sometimes
Standardized, citable methods	✓	depends on who built it	✓
Traceability and versioning	✓	✕	partial
Nothing to install (web)	✓	✓	✕
Automatic standards updates	✓	✕	paid
Field-validated, standards-based	field-validated	—	black box
Learning curve	minutes	inherited and fragile	weeks

Informative comparison, based on the typical use of each alternative. “Engineering software” refers to proprietary sizing packages.

Every number has a standard behind it.

No black box. Every calculation follows an established method, citable in the report — the same ones that experts, inspectors and auditors recognize.

Darcy-Weisbach
Colebrook-White
Serghides
Dunlop
IEC 60534-2-1
ISO 5167-2
Joukowsky / Michaud
API 520 / 526
IAPWS-IF97

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2D/3D diagrams of your system

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“I am an engineer. I got tired of redoing the same sizing in a spreadsheet that no one dares to touch. I built LOGOS to give the calculation what Excel never gave it: provenance.”

— the team behind LOGOS