UP/1B Calculator is a step-by-step guide and calculation tool for Gas Safe registered engineers carrying out installation pipework tightness testing to IGEM/UP/1B Edition 4. The app guides you through every stage of the tightness test procedure: • Initial Volume Test (IVt) — calculates the correct test pressure and acceptable pressure drop for the installation size • Let-By Test — checks for meter regulator let-by • Tightness Test — records pressure readings and determines pass or fail • LDF Check — guides leak detection fluid testing of all disturbed joints • Purge — calculates purge volume and checks for safe gas release • PDF Record — generates a professional gas tightness test record ready to save or share Designed specifically for natural gas installations at low pressure (nominal operating pressure ≤ 21 mbar) in accordance with IGEM/UP/1B Edition 4. All test records are saved to your account and sync across devices — ideal for engineers working across multiple sites. For use by Gas Safe registered engineers only.