Overview
EN ISO 17778:2015 specifies a laboratory method to determine the gaseous flow rate / pressure drop relationship of components used in plastics piping systems (fittings, valves and ancillaries). Tests are carried out using air at 25 mbar and produce a characteristic factor that relates pressure loss to flow rate. The standard is intended for manufacturers, test laboratories and specifiers who need repeatable, comparable gas-flow performance data for plastic piping components.
Key Topics
- Scope and principle
- Method for measuring pressure drop (Δp) versus volumetric flow (Q) under a constant main pressure of (25 ± 0.5) mbar.
- Outputs include velocity (V), a flow/pressure factor (F) and equivalent flow rates for other gases.
- Apparatus and accuracy
- Pressure controller to hold main line pressure at 25 mbar.
- Flow meter (positive displacement or turbine) with accuracy ±2%.
- Pressure manometers: main-line manometer (class 0.6) and differential manometer (class 0.25) per EN 837‑1.
- Typical test rig schematic (pressure controller, flow meter, test component, outlet valve).
- Test pieces & preparation
- Component fused/connected between two plastic pipe lengths; pressure tapping points flush with bore.
- For tapping tees, pressure drop measured through the outlet branch.
- Procedure & acceptance criteria
- Perform tests at (23 ± 2) °C, vary outlet valve to obtain multiple Q/Δp pairs.
- Minimum five data sets required; velocity V must include at least one ≤ 2.5 m/s and one ≥ 7.5 m/s (if unattainable at 25 mbar, report observation).
- Calculations
- Velocity V = Q / A (Q in m³/h, A bore area in m²).
- Factor F = Δp / Q² (average F expresses the pressure-drop/flow relationship).
- Convert air flow to other gases using the density ratio provided by the standard (Q_gas = (ρ_air / ρ_gas) × Q_air).
- Test report content
- Reference to ISO 17778, component ID, materials, measured Q/Δp/V, average F, calculated flows for air and other gases, deviations and test date.
Applications
- Establishing performance data for plastic fittings, valves and ancillaries used in low‑pressure gas distribution and industrial systems.
- Supporting product datasheets, type testing, conformity assessment and sizing/selection in gas distribution networks.
- Useful to manufacturers, independent test laboratories, utilities, system designers and regulatory bodies specifying flow/pressure-loss limits.
Related Standards
- Supersedes EN 12117:1997.
- References EN 837‑1 (pressure gauge classes) and other normative documents cited in the standard.
Keywords: ISO 17778:2015, plastics piping systems, fittings valves ancillaries, flow rate pressure drop, gaseous flow testing, 25 mbar, differential pressure, test method.
