Orifice bore for a flow and transmitter range, the flow from a measured differential, or the differential for a flow, by ISO 5167-2 — with β, C, ε, permanent loss, limit checks and straight lengths.
USD 29 one-time purchase
Download the sample report (PDF)
Need it once? Use it online: check your data free, unlock results from USD 9 for 3 runs.
What it does
Three ways to use it
Size the bore for a full-scale flow and differential range, find the flow from a measured differential, or the differential a new flow gives through an existing plate.
Flange, corner and D–D/2 taps
Reader-Harris/Gallagher discharge coefficient and the expansibility factor, with their uncertainties.
Liquids, gases and steam
Built-in fluid library, or your own density and viscosity; standard volume flow for gases.
Real conditions
Thermal expansion of the plate and the pipe at the flowing temperature; permanent pressure loss.
Limit checks
β, bore, pipe size, Reynolds number and pressure ratio, with plain-language findings and the straight lengths for the nearest fitting.
Flow table and report
Flow against differential from 120 % to 10 % of full scale, with a chart and a one-page report for the instrument datasheet.
Built for engineers
- Visible formulas — nothing hidden, so you can check every step.
- Fully referenced — methods from the standard references, checked against their published worked examples.
- Safe to share — sheets are protected against accidental edits, with an open password so you can still customise.
- Built-in input checks — clear warnings for impossible inputs and values outside typical ranges.
For engineering estimates; verify against site data. Code-based methods are aligned with the publicly documented procedure; they are not a licensed reproduction or a certification.
Preview the workbook
Real pages from the workbook with its built-in example loaded (example data, not a measured plant). Choose a page below, or select the large image to enlarge it.
A worked case
The case: size a flange-tapped orifice for 100,000 kg/h of water at 30 °C in 6-inch Schedule 40 pipe, with 250 mbar at full scale. The workbook gives: bore 88.32 mm at 20 °C, β = 0.5733, discharge coefficient C = 0.60681 (Reader-Harris/Gallagher, ISO 5167-2), permanent pressure loss 164 mbar, and the straight lengths needed — 9 D upstream and 3 D downstream. The report adds a flow-against-differential table from 10 to 120 % of the range and a chart for the DP transmitter.
Specification and checks
| Format | Excel workbook (.xlsx), no macros |
| Version | v1.0 |
| Works in | Excel 2010 or later, Windows and Mac |
| Units | SI, US and British, mixed freely |
| Includes | Guide tab with method and references, calculator, print-ready report |
| Checked against | 25 of 25 checks within tolerance against a separate implementation of ISO 5167-2 and Perry's Chemical Engineers' Handbook, for water, air, steam and a viscous oil. |
| Free version | Try the online calculator |
Free calculator, online tool or Excel tool?
| Free calculator | Online tool | Excel tool | |
|---|---|---|---|
| What it does | Flow from differential pressure by ISO 5167-2 (Reader-Harris/Gallagher), for liquids and gases. | The full Excel tool, run in your browser | Orifice bore for a flow and transmitter range, the flow from a measured differential, or the differential for a flow, by ISO 5167-2 — with β, C, ε, permanent loss, limit checks and straight lengths. |
| Cost | Free, no sign-up | 3 runs for USD 9, or every online tool for USD 15 a month | USD 29 once, yours to keep |
| Input checks and findings | Basic warnings | Every input checked, with findings and recommendations | Every input checked, with findings and recommendations |
| Report for your calculation file | Print the web page | Printable results sheet | Print-ready report with your plant, tag, document number, revision and sign-off |
| Formulas | Method described on the page | Method described in the guide | Every formula visible in its cell |
| Save, edit and rerun your cases | — | Each run separately | Yes — keep and edit your own file |
| Works offline, on a plant PC | — | — | Yes — Excel 2010 or later, Windows and Mac |
Compatibility, licence and support
| File | Excel workbook (.xlsx), no macros, version v1.0; works in Excel 2010 or later on Windows and Mac. Sheets are protected against accidental edits, with an open password so you can customise. |
| Licence | Single user. A team licence (up to 5 named users) is 3 × the shop price; site licences on request — licence terms. |
| Updates | Updates to this major version are included; download them again from the link in your receipt. |
| Support | Email [email protected] with your order number — questions on the method, your inputs or your results are welcome. |
| Refunds | If the tool does not work as described, or has an error we cannot fix, email [email protected] with your order number within 14 days of purchase and we will refund you in full. Refunds are not offered for a change of mind once a file has been downloaded. Read the full refund policy. |