Four DIN Hydraulic Fitting Types and How They Seal

DIN metric and BSPP thread styles are common in European hydraulic and pneumatic equipment. DIN-type tube fittings are commonly associated with ISO 8434-1, DIN 2353, and DIN EN 3850 requirements, which support interchangeability across compatible fitting systems.

Four DIN-related styles often appear in hydraulic and mobile equipment work: DIN 2353 24 degree cone fittings, DIN 2353 pressure series fittings, metric standpipe fittings, and banjo fittings.

1. DIN 2353 24 Degree Cone

DIN 2353 24 degree cone fittings use straight metric threads on both the male and female components. The tube OD connection mates with a 24 degree seat in the male fitting.

The mating female side may be a DIN 2353 female tube fitting, a metric tube with cutting ring and nut, or a 24 degree cone with an O-ring that is welded or formed on the metric tube.

The seal is made between the 24 degree seat on the male end and the matching female end. The seat angle should be measured from the fitting centerline with the proper gauge.

2. DIN 2353 Pressure Series

DIN 2353 fittings are grouped into pressure series. LL is used for extra-light, low-pressure applications. L is used for light or medium-pressure applications. S is the heavy series for high-pressure applications.

The series is identified by measuring the tube OD, thread size, and thread pitch. A light series and heavy series part may look similar, but they should not be treated as interchangeable.

3. Metric Standpipe Fittings

A metric standpipe fitting is commonly made from a preassembled standpipe, bite sleeve, and nut. It connects a metric tube to a 24 degree conical bore.

When the nut is tightened onto a DIN 2353 male connection, the bite sleeve compresses onto the standpipe tube and creates the seal. This style is useful when the connection needs a tube-style transition rather than a normal threaded adapter body.

4. Banjo Fittings

Metric and BSPP banjo fittings use a hollow bolt and a spherical union for fluid transfer. They are common in mobile and automotive-style systems because the hose or pipe direction can be adjusted while the bolt is tightened independently.

The main benefit is that the connected hose does not have to twist as the fitting is installed. Banjo fittings are used in brake caliper connectors, SCR fuel dosing, fuel filters, hydraulic clutch lines, power steering lines, turbocharger oil feed lines, and variable valve timing systems.

Correct DIN fitting selection depends on the thread, tube OD, pressure series, sealing style, and the movement or routing needs of the equipment.