Overview
ISO 13948-1:2015 specifies dimensions and requirements for mechanical, threaded low‑pressure connections used on diesel fuel injection pumps and fuel injectors. It applies to connections for low‑pressure fuel, lubrication oil and air supply and defines five preferred threaded connection types (A–E). Type A (banjo connection) is commonly used for both pumps and injectors; Types B–E are intended for diesel fuel injection pumps. The standard includes preferred sizes, dimensional tolerances and designation rules to support interchangeability and safe, leak‑free connections in diesel engine fuel systems.
Key topics and technical requirements
- Five threaded connection types (A–E):
- Type A: Banjo connection using external sealing washers; suitable for pumps and injectors.
- Type B: O‑ring seal on a cone (based on SAE J2244/1 / ISO 6149‑1).
- Type C: Compression seal on a cone inboard of the thread.
- Type D: Internal rubber ring seal (flexible), radial compression inboard of the thread.
- Type E: External rubber ring seal (flexible), sealing face external to the main body; preferred for flexible pipe fittings.
- Dimensions and tolerances: Detailed in Tables 1–5 (preferred sizes indicated). Threads are recommended at tolerance grade 6H / 6g (medium).
- Applications covered: fuel inlet and return/back‑leakage, lubrication oil feed (inline pumps), and air (engine inlet pressure signal).
- Designation convention: e.g., ISO 13948-1 – A – M10 × 1,25 (standard part – type – thread).
- Surface finish and symbols: Surface roughness referenced to ISO 4288; dimensional symbols and thread/seat depths are defined for consistent interpretation.
Practical applications and users
This standard is essential for:
- Engine and fuel system designers specifying low‑pressure connections to ensure compatibility and manufacturability.
- OEMs and component manufacturers producing fuel injection pumps, injectors, fittings and mating pipes.
- Aftermarket and maintenance engineers selecting replacement connectors and ensuring correct sealing methods.
- Quality and test engineers verifying dimensional conformity and leak‑tight assembly.
Typical use cases include low‑pressure fuel inlet/outlet connections on diesel pumps, lubrication oil feed ports on inline pumps, and engine pressure‑signal fittings.
Related standards
- ISO 13948-2: Non‑threaded (push‑on) low‑pressure connections
- ISO 2974: High‑pressure end‑connections for pumps and injectors
- ISO 6149-1: Ports and stud ends with metric threads and O‑ring sealing (related O‑ring designs)
- ISO 261 / ISO 4288: Thread sizing and surface texture references
ISO 13948-1:2015 helps standardize low‑pressure threaded connections in diesel engines for improved interchangeability, leak prevention and system reliability. Keywords: ISO 13948-1:2015, diesel engines, fuel injection pumps, fuel injectors, low‑pressure threaded connections, banjo connection, O‑ring seal, compression seal, rubber ring seal.