ISO 17778:2015

Overview

ISO 17778:2015 defines a standardized laboratory method for determining the gaseous flow rate / pressure drop relationship of components used in plastics piping systems (fittings, valves and ancillaries). The procedure is carried out using air at 25 mbar and produces a single characteristic relationship (factor F) that links measured pressure drop and flow rate for a given component size and arrangement. This edition is aligned with EN 12117:1997 and is intended for manufacturers, test laboratories and product specifiers.

Key topics and requirements

• Scope and principle
  • Measures pressure drop across a component while maintaining a constant main-line pressure of (25 ± 0.5) mbar.
  • Uses repeated flow/pressure points to derive an average relationship between flow and Δp.
• Apparatus
  • Pressure controller capable of 25 mbar, flow meter (±2%), main-line manometer, differential pressure manometer (class 0.25), and outlet valve arranged per the standard’s schematic.
• Test piece preparation
  • Component fused or connected between plastic pipes of matching bore; pressure tangs flush with bore; special arrangement for tapping tees (measure through outlet branch).
• Procedure highlights
  • Perform tests at ambient (23 ± 2) °C.
  • Vary outlet valve to obtain at least five Q/Δp data sets with velocity V range: ≤2.5 m/s and ≥7.5 m/s (if attainable at 25 mbar).
  • Record flow (Q) and differential pressure (Δp) for each point.
• Calculations
  • Velocity: V = Q / A (Q in m3/h, A in m2 → V in m/s).
  • Flow/pressure factor: F = Δp / Q² for each reading; report the average F.
  • Equivalent flow for other gases is calculated using gas density per the standard (conversion by density ratio).
• Test report
  • Must reference ISO 17778, identify test pieces (size, material, manufacturer code), list all measured Q, Δp, V, average F, converted gas flows, deviations, and test date.

Applications and users

• Manufacturers of plastic fittings, valves and ancillaries use ISO 17778 to generate comparable performance data for product datasheets and type testing.
• Independent test laboratories adopt the method for certification, R&D and quality control.
• Gas distribution companies, system designers and specifiers use the results to size components, evaluate pressure losses, and convert air test results to other gases (e.g., natural gas) using the density-based conversion.
• Regulatory bodies and standards committees reference the method when specifying performance requirements for piping components.

Related standards

• EN 12117:1997 (replaced/aligned with ISO 17778:2015)
• EN 837-1 (pressure gauge requirements referenced for manometer classes)

Keywords: ISO 17778:2015, plastics piping systems, fittings valves ancillaries, flow rate pressure drop, gaseous flow testing, air 25 mbar, test method, pressure drop relationship, flow meter, manometer, conversion by density.