ISO 7440-1:1991

Overview

ISO 7440-1:1991 - Road vehicles - Fuel injection equipment testing - Part 1: Calibrating nozzle and holder assemblies - specifies the design, components and identification of calibrating nozzle and holder assemblies used to test and set diesel (compression‑ignition) fuel injection pumps on test benches. This second edition (1991) replaces the 1985 edition and is intended to ensure reproducible flow‑gauge behaviour for calibration and pump testing.

Key topics and technical requirements

• Two alternative calibrating assemblies
  • With single‑hole orifice plate (figure-based designs and plate numbers defined).
  • With delay pintle type nozzle (as specified in ISO 4010).
• Flow ranges
  • Up to approximately 300 mm3/stroke with single‑hole orifice plate.
  • Up to approximately 150 mm3/stroke with delay pintle nozzle.
• Component specification (3.2.1–3.2.8) - includes holder body (vented or unvented), spring, inlet stud with edge filter, needle valve assembly, single‑hole orifice plates, distance sleeve, delay pintle nozzle, and retaining nuts. Critical dimensions and surface‑finish requirements are provided.
• Inlet stud / edge filter characteristics
  • Filter radial clearance 0.02–0.033 mm; minimum filter clearance area 7.3 mm2; flow area for three flutes ≥7.5 mm2.
  • Internal volume ≈1 450 mm3 ±40 mm3.
  • Filter flow at 0.3 MPa: 4 750–6 500 cm3/min (using calibration fluid per ISO 4113 at ~40 °C). Minimum assembled holder flow at 0.3 MPa: ≥2 000 cm3/min.
  • Test supply pressure tolerance: ±0.03 MPa.
• Identification code
  • A 4‑element code defines standard number, nozzle/orifice type, component content and nozzle opening pressure (given in 105 Pa - bar). Example: ISO 7440 A13‑170 (170 bar opening pressure).

Practical applications and users

• Used by fuel injection equipment manufacturers, engine/OEM test laboratories, independent calibration and verification workshops, and research labs that perform diesel pump set‑up, verification and routine testing.
• Applies for: bench calibration of injection pumps, definition of test fixtures, procurement/specification of calibrating nozzle assemblies, and ensuring repeatable flow measurement during development, production testing and maintenance.
• Emphasises careful handling and maintenance because assemblies function as flow gauges.

Related standards

• ISO 7440-2:1991 - Orifice plate flow‑measurement (companion test procedure)
• ISO 4010 - Delay pintle type nozzle
• ISO 4113 - Calibration fluid for diesel injection equipment
• ISO 2697, ISO 2699, ISO 4093, ISO 7876-2 - related injector, holder, pipe and vocabulary standards

Keywords: ISO 7440-1, calibrating nozzle and holder assemblies, fuel injection equipment testing, diesel injection pump calibration, orifice plate, delay pintle nozzle, flow gauge, test bench.