DKR inch fittings (C11)
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DKR C11 inch fittings with BSP female thread
DKR C11 inch fittings are straight hydraulic hose fittings with a swivel nut and BSP female thread. The connection is sealed on a 60° cone, making DKR fittings commonly used in hydraulic hoses of construction, agricultural, industrial, and mobile power hydraulic systems.
The HYDRON offer includes variants adapted to different hose diameters and BSP thread sizes. When choosing, the hose DN, thread size, and seal type must be matched simultaneously. The thread dimension alone is not sufficient for correct fitting selection.
Key features of DKR C11 fittings
- product type: straight hydraulic hose fitting,
- group designation: DKR / C11,
- thread type: inch BSP,
- thread type: female,
- nut type: swivel,
- sealing method: 60° cone,
- purpose: crimped hydraulic hoses,
- available in various hose DN diameters,
- available in various BSP thread sizes,
- fitting selection depends on the hose, ferrule, and parameters of the entire assembly.
What does DKR mean?
The DKR designation refers to a hydraulic fitting with a BSP female thread and a sealing surface cooperating with a 60° cone. In the Polish commercial designation, the group of straight fittings of this type is often described with the C11 symbol.
The swivel nut facilitates hose assembly because there is no need to rotate the entire hydraulic hose while tightening.
BSP thread in DKR fittings
BSP is a family of inch threads widely used in hydraulics. They are found in European machines, industrial installations, hydraulic power units, and many mobile machines.
The DKR C11 fitting category includes, among others, popular sizes:
- 1/8" BSP,
- 1/4" BSP,
- 3/8" BSP,
- 1/2" BSP,
- 5/8" BSP,
- 3/4" BSP,
- 1" BSP,
- 1.1/4" BSP,
- 1.1/2" BSP,
- 2" BSP.
60° Cone - where is the tightness created?
In DKR fittings, the tightness of the connection is achieved on the 60° conical surface. The thread is primarily responsible for pressing the mating elements together.
This means that this connection should not be treated like a typical pipe thread where tightness is created on the threads. A correct connection requires compatible geometry of the sealing surfaces.
DKR vs BSP - why is the thread name alone not enough?
This is one of the most important points in selection. Information that a fitting has a BSP thread does not yet define the complete connection method.
The following must also be confirmed:
- female thread,
- correct BSP size,
- 60° cone,
- hydraulic hose DN,
- proper crimp ferrule.
Two fittings with the same thread may be intended for hoses with different internal diameters.
How to recognize the BSP thread size?
If the marking on the old fitting is illegible, measuring the thread diameter with a caliper can be helpful.
Approximate external diameters of mating BSP threads are:
- BSP 1/8" - approximately 9.3-9.7 mm,
- BSP 1/4" - approximately 12.9-13.1 mm,
- BSP 3/8" - approximately 16.3-16.6 mm,
- BSP 1/2" - approximately 20.5-20.9 mm,
- BSP 5/8" - approximately 22.6-22.9 mm,
- BSP 3/4" - approximately 26.1-26.4 mm,
- BSP 1" - approximately 33.0-33.2 mm,
- BSP 1.1/4" - approximately 41.5-41.9 mm,
- BSP 1.1/2" - approximately 47.4-47.8 mm,
- BSP 2" - approximately 59.2-59.6 mm.
These values should be treated as an aid for identification. For a certain selection, you must also check the thread pitch and type of sealing surface.
How to match a DKR fitting to the hose diameter?
The second basic parameter is the DN internal diameter of the hydraulic hose. The fitting must have a suitable tail intended for the specific hose size.
In this group of fittings, variants can be found for, among others:
- DN05,
- DN06,
- DN08,
- DN10,
- DN12/13,
- DN16,
- DN19/20,
- DN25,
- DN32,
- DN38/40.
The fitting should not be selected solely according to the thread on the machine side. The crimped part must simultaneously be compatible with the hydraulic hose used.
DKR fitting and crimp ferrule form one system
A hydraulic fitting does not work alone. To make a hose assembly, a crimp ferrule suitable for the type of hose and fitting design is also needed.
Correct selection includes:
- type of hydraulic hose,
- DN diameter,
- DKR fitting type,
- BSP thread size,
- appropriate ferrule,
- proper crimping diameter.
An incorrect combination of fitting, ferrule, and hose can lead to insufficient crimping, hose damage, or the fitting being pulled out during operation.
Straight DKR or 90° DKR?
The DKR C11 fitting has a straight design and works best where the hose can be routed without sharp bending directly at the crimp.
If the installation space is limited or the hose must change direction right at the connection, it is worth considering DKR 90° C12 fittings.
Also available are DKR 45° fittings, which allow routing the hose at a gentler angle.
When is it worth using a straight DKR fitting?
The straight version is a good choice when:
- the connection is located in an open space,
- the hose has a sufficient bending radius,
- there is no collision with the machine frame or housing,
- the hose can exit axially from the connection point,
- we want the simplest possible hose routing.
The fewer unnecessary changes in direction, the easier it is to limit local pressure losses and unnecessary hose stress.
BSP vs BSPT should not be automatically swapped
In hydraulics, both BSP and BSPT threads can be found. Despite the similar designation, these are not identical terms.
With DKR fittings, the type of mating socket and the 60° cone should primarily be checked. Simply stating that the connection has an "inch thread" is insufficient.
Working pressure of the DKR fitting
The allowable pressure depends on the specific fitting size. Within this category, there are variants with different maximum pressure values.
Therefore, one value should not be assigned to the entire DKR C11 group. During selection, the parameters of the specific variant and the entire hose assembly must be checked.
In practice, the maximum pressure of a complete hose assembly is limited by its weakest element, which could be the hose, the fitting, the ferrule, or the mating connection.
Material and protection of DKR fittings
Most standard DKR fittings in this category are made of steel and have zinc plating for surface protection.
In selected applications, stainless steel variants are also available for installations requiring increased corrosion resistance.
Where are DKR BSP fittings used?
DKR fittings are found in many hydraulic systems, especially in machines using the BSP inch standard.
- construction machinery,
- excavators and loaders,
- agricultural machinery,
- forestry machinery,
- tractors and hydraulic attachments,
- hydraulic power packs,
- industrial machinery,
- municipal equipment,
- specialized vehicles.
Most common mistakes when selecting a DKR fitting
- selection based only on the BSP thread size,
- ignoring the hose DN diameter,
- confusing the 60° cone with another seal type,
- confusing BSP with another inch thread,
- using the wrong crimp ferrule,
- choosing a straight version where the hose must be sharply bent,
- assuming one working pressure for all sizes.
How to check an old fitting before ordering?
- read the hose marking and determine its DN,
- measure the thread of the mating connection,
- determine the BSP size,
- confirm the female thread in the fitting,
- check the 60° sealing surface,
- compare the shape of the old fitting,
- check the hose type and required crimp ferrule.
DKR fittings for making hydraulic hose assemblies
C11 fittings are intended for crimping onto appropriately selected hydraulic hoses. If you want to order a ready-made assembly, you can use the offer of HYDRON crimped hydraulic hoses.
You can also independently determine the hose length and endings using the hydraulic hose configurator.
Also select the appropriate hydraulic adapters
A DKR fitting must work with the correct connection on the machine side. When repairing or modernizing, it is worth checking the entire connection point.
In the category of hydraulic connectors you will find adapters and elements needed to build installations in various thread standards.
FAQ - DKR inch C11 fittings
What does DKR mean?
DKR is a hydraulic hose fitting with a BSP female thread, a swivel nut, and a 60° cone seal. The straight version is designated in this group as C11.
Does DKR seal on the thread?
No. Tightness is achieved on the mating 60° conical surface, while the thread is primarily responsible for the pressure of the elements.
Is it enough to know the BSP thread size?
No. You also need to select the hose DN diameter, the appropriate crimp ferrule, and confirm the type of sealing surface.
How does DKR C11 differ from DKR90 C12?
C11 is a straight fitting, while C12 has a 90° angled design. Both solutions can use BSP threads and 60° cones, but they serve different hose routing methods.
How to match a DKR to an old hose assembly?
You should check the hose DN, thread size and pitch, 60° cone, and the design of the old fitting. If there are no markings, measuring with a caliper and comparing dimensions is helpful.