HOW WE WORK

Editorial and review policy

Every calculator, table and guide on Engineering Desk Tools is written for people who maintain and run plants. This page explains how the content is prepared, checked and corrected.

Who writes the content

The site is run by a maintenance professional working in industrial plants in Saudi Arabia, with day-to-day experience of electrical, instrumentation, rotating equipment and utility systems. The author prefers to stay anonymous; the site is judged on whether its methods and results are correct, and every formula is shown so you can check it yourself.

Where the formulas come from

Calculators use standard engineering relationships and published references, for example:

• Unit conversion factors from the NIST guide to SI units.
• Electrical relationships for single-phase and three-phase power, and IEC/IEEE practice for transformers and short-circuit current (IEC 60076, IEC 60909).
• ISO 281 for bearing rating life, IEC 60751 for platinum RTDs and IEC 60534 for control valve sizing principles.
• Darcy–Weisbach and the Swamee–Jain friction factor for pipe pressure drop, and the pump affinity laws.
• Reliability methods (MTBF, Weibull, FMEA) as used in maintenance and reliability engineering.

The relevant reference is named on each calculator page.

How calculations are checked

1. The formula is written out on the page with its units and assumptions.
2. Results are checked against hand calculations and, where available, published tables or worked examples.
3. Tables on each page are generated from the same formula as the calculator, so the table and the calculator always agree.
4. Limits are stated plainly: what the calculation does not include, and when a full study, a manufacturer's method or a standard is needed instead.

Review dates

Each calculator page shows the date of its most recent review. The date changes when the formula, tables or explanation are checked or updated. It is not a certification or a guarantee.

Corrections

If you find an error in a formula, unit, table or result, please contact us with the page address, your inputs, the result you expected and the reference you used. Confirmed errors are corrected and the review date is updated.

Independence and advertising

The calculators and templates are free. Advertising may appear to support the site. Advertisers have no influence on the content, formulas or results. Any affiliate link will be clearly marked next to the link.

Use of results

Results are estimates for learning, planning and checking. They do not replace equipment data, site procedures, applicable codes or a qualified engineer's review for safety-critical decisions. See the terms of use.