ISO 14681:1998

Diesel engines - Fuel injection pump testing - Calibrating fuel injectors

Moteurs diesels — Essai des pompes d'injection de carburant — Porte-injecteurs de carburant complets de calibration

General Information

• Status: Published
• Publication Date: 08-Jul-1998
• ICS: 43.060.40 - Fuel systems
• Technical Committee: ISO/TC 22/SC 34 - Propulsion, powertrain and powertrain fluids
• Drafting Committee: ISO/TC 22/SC 34/WG 2 - Injection equipment
• Current Stage: 9060 - Close of review
• Completion Date: 02-Sep-2030

Relations

• Consolidated By: ISO/TS 22367:2008 - Medical laboratories - Reduction of error through risk management and continual improvement
• Effective Date: 06-Jun-2022

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.

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 14681
First edition
1998-07-15
Diesel engines — Fuel injection pump
testing — Calibrating fuel injectors
Moteurs diesels — Essai des pompes d'injection de carburant — Porte-
injecteurs de carburant complets de calibration
A
Reference number
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO
member bodies). The work of preparing International Standards is normally carried out through ISO technical
committees. Each member body interested in a subject for which a technical committee has been established has
the right to be represented on that committee. International organizations, governmental and non-governmental, in
liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical
Commission (IEC) on all matters of electrotechnical standardization.
Draft International Standards adopted by the technical committees are circulated to the member bodies for voting.
Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote.
International Standard ISO 14681 was prepared by Technical Committee ISO/TC 22, Road vehicles, Subcommittee
SC 7, Injection equipment and filters for use on road vehicles.
Annex A of this International Standard is for information only.
©  ISO 1998
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced
or utilized in any form or by any means, electronic or mechanical, including photocopying and
microfilm, without permission in writing from the publisher.
International Organization for Standardization
Case postale 56 • CH-1211 Genève 20 • Switzerland
Internet [e-mail]
Printed in Switzerland
ii
© ISO
Introduction
Calibrating fuel injectors are intended to simulate closely the function of fuel injectors in the fuel injection system of a
diesel (compression-ignition) engine.
Injection pumps for emission-controlled engines require a new generation of calibrating injectors in order to comply
with the higher injection pressures. The field of application is similar to those of the calibrating injectors specified in
ISO 7440-1 and of the calibrating nozzle specified in ISO 4010. Compared with calibrating injectors according to
ISO 7440-1, the new designs show the following differences:
 change-over from high spring nozzle holder to low spring nozzle holder,
 reduction of masses,
 reduction of dead volumes, e.g. edge filter.
Therefore, the following parts are modified:
 nozzle holder body,
 nozzle retaining nut,
 edge filter,
 spring,
 needle valve assembly and pintle nozzle,
 distance sleeve.
The following parts are not modified:
 the orifice plates with the orifice diameter range from 0,4 mm to 0,8 mm,
 the optional spray damper,
 the distance sleeve of the calibrating fuel injector with the single hole orifice plate.
iii
INTERNATIONAL STANDARD  © ISO ISO 14681:1998(E)
Diesel engines — Fuel injection pump testing — Calibrating fuel
injectors
1 Scope
This International Standard specifies two types of calibrating injectors intended for testing and setting diesel fuel
injection pumps on test benches.
It applies to
a) calibrating injectors for different orifice plates, max. delivery range 400 mm³/stroke;
b) calibrating injectors with pintle type nozzle, max. delivery range 200 mm³/stroke.
The field of application is similar to the calibrating injectors specified in ISO 7440-1 and to the calibrating nozzle
specified in ISO 4010.
Compared to the calibrating injector specified in ISO 7440-1, the calibrating injectors specified in this International
Standard represent an advanced stage of design which is more appropriate to modern high pressure/high
performance fuel injection systems.
Specification of the type of calibrating fuel injectors to be used, the appropriate single hole orifice plate size or pintle
nozzle (as applicable), high pressure pipes, exact limits, etc. is left to the manufacturer of the injection equipment
and/or the manufacturer of the engine.
2 Normative references
The following standards contain provisions which, through reference in this text, constitute provisions of this
International Standard. At the time of publication, the editions indicated were valid. All standards are subject to
revision, and parties to agreements based on this International Standard are encouraged to investigate the
possibility of applying the most recent editions of the standards indicated below. Members of IEC and ISO maintain
registers of currently valid International Standards.
1)
ISO 4010:— , Diesel engines — Calibrating nozzle, delay pintle type.
ISO 4113:1988, Road vehicles — Calibration fluid for diesel injection equipment.
ISO 7440-1:1991, Road vehicles — Fuel injection equipment testing — Part 1: Calibrating nozzle and holder
assemblies.
ISO 7440-2:1991, Road vehicles — Fuel injection equipment testing — Part 2: Orifice plate flow-measurement.

1)
To be published. (Revision of ISO 4010:1977)
© ISO
3 Requirements
3.1 Calibrating fuel injectors
3.1.1 With single hole orifice plate
The two alternative designs of the calibrating fuel injectors with the single hole orifice plate specified in figure 11 are
shown in figure 1.
3.1.2 With delay pintle type nozzle
The two alternative designs of the calibrating fuel injectors with the delay pintle type nozzle specified in figure 14 are
shown in figure 2.
3.2 Components
The calibrating fuel injectors consist of the components specified in 3.2.1 to 3.4.2 with their functionally critical
dimensions.
3.2.1 Holder body
The holder body may include two spill tubes:
 one tube for the leakage fuel passing the needle valve assembly in the direction to the spring housing;
 another tube (optional) used with vented holder only.
The holder body is shown in figure 3.
3.2.2 Spring
The spring is shown in figure 5. It is designed for low stress in order to prevent fatigue.
3.2.3 Spring seat
The spring seat, which provides the connection of the low situated spring with the needle, is shown in figure 6.
3.2.4 Inlet stud with edge filter
The inlet stud with edge filter is shown in figure 7. It may be flow-tested as shown in figure 8. The outlet of the fixture
(within dotted lines) shall be ambient pressure.
© ISO
Dimensions in millimetres
Alternative 1: Preferably for use with calibrating test benches having open spray chamber
Alternative 2: Preferably for use with calibrating test benches having closed spray chamber
Key
1  Retaining nut, alternative 1
2  Retaining nut, alternative 2
3  Needle valve assembly
4  Single hole orifice plate
5  Distance sleeve
6  Holder body
7  Inlet stud with edge filter
8  Spring
9  Spring seat
10  Adaptor plate
Figure 1 — Calibrating fuel injector with single hole orifice plate
© ISO
Dimensions in millimetres
Alternative 1: Preferably for use with calibrating test benches having open spray chamber
Alternative 2: Preferably for use with calibrating test benches having closed spray chamber
Key
1  Retaining nut, alternative 1
2  Retaining nut, alternative 2
3  Delay pintle type nozzle
4  Holder body
5  Inlet stud with edge filter
6  Spring
7  Distance sleeve
8  Spring seat
9  Adaptor plate
Figure 2 — Calibrating fuel injector with delay pintle type nozzle
© ISO
Dimensions in millimetres
Figure 3 — Holder body
Dimensions in millimetres
Figure 4 — Adapter plate
Dimensions in millimetres
Figure 5 — Spring
Dimensions in millimetres
Figure 6 — Spring seat
© ISO
Dimensions in millimetres
a) Edge filter with flutes (schematic)
b) Inlet stud with edge filter
Characteristic Value
Filter clearance (radial) 0,02 mm to 0,0
...