ISO 14681:1998

Overview

ISO 14681:1998 specifies calibrating fuel injectors used for testing and setting diesel engine fuel injection pumps on test benches. The standard covers two injector types - those using single‑hole orifice plates (max delivery 400 mm³/stroke) and delay pintle‑type nozzles (max delivery 200 mm³/stroke) - and defines component geometry, flow/pressure control values, and a designation/coding system for calibrating injectors.

Key topics and technical requirements

• Injector types and limits
  • Single‑hole orifice plate design (orifice sizes 0.4–0.8 mm).
  • Delay pintle‑type nozzle design (specific air‑flow control values provided for needle lifts).
• Critical components defined
  • Holder body (vented or non‑vented), retaining nut, inlet stud with edge filter, spring and spring seat, needle valve assembly, distance sleeves, adapter plate.
• Edge filter and flow requirements
  • Filter clearance: 0.02–0.031 mm; internal volume 700 mm³ ±20 mm³.
  • New filter flow at 0.3 MPa: 2 800–4 600 cm³/min; assembled holder minimum flow: 2 000 cm³/min.
• Orifice plate flow ranges
  • Orifice plates (0.4, 0.5, 0.6, 0.7, 0.8 mm) have specified minimum and maximum high‑pressure flow limits when tested per ISO 7440‑2.
• Delay pintle nozzle control values
  • Air flow vs. needle lift control values are specified (example values at defined lifts and ambient conditions).
• Designation system
  • A four‑part code format (e.g., ISO 14681 A13‑207) specifies standard number, code letter, component content, and nozzle opening pressure (example “207” = 207 bar in the example given).

Applications and who uses it

• Test bench manufacturers and calibration equipment suppliers - to design and supply calibrating injectors compatible with modern high‑pressure diesel pumps.
• Injection pump manufacturers and engine OEMs - for pump testing, pump setting, and ensuring component compatibility with emission‑controlled high‑pressure systems.
• Calibration technicians and test laboratories - for specifying correct orifice/nozzle types, holder variants, and nozzle opening pressure settings.
• Quality and compliance engineers - to align pump testing procedures with international standards and traceable designation codes.

Related standards (normative references)

• ISO 4010 (calibrating nozzle, delay pintle type)
• ISO 4113 (calibration fluid)
• ISO 7440‑1 (calibrating nozzle and holder assemblies)
• ISO 7440‑2 (orifice plate flow measurement)

Keywords: ISO 14681, calibrating fuel injectors, diesel engines, fuel injection pump testing, orifice plate, pintle nozzle, edge filter, nozzle opening pressure, test benches.