Identifying 24° Tube Fittings

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24° tube fittings, commonly referred to as "Bite-Type", rank among the most widely used fittings around the world, incorporating one of the most sophisticated tube fitting systems available. This advanced design allows for exceptional durability, capable of handling high pressures and intense vibrations, primarily due to its innovative cutting ring feature. The cutting ring, which is a ferrule with sharp edges, is compressed against the tube when the associated nut is tightened. This action forces the ferrule into the taper of the fitting, creating an effective seal around the tube. It is vital to exercise caution when identifying these fittings, as DIN fittings use Metric threading and bear a close resemblance to other Metric fittings.

Design Characteristics of 24° Throat Angle

The design of the fitting includes a 24° tapered throat located adjacent to the tube receptacle. This design is essential for guiding the cutting ring into position as torque is applied to the nut. Adhering closely to the specified installation instructions is crucial for forming a reliable seal during assembly. For detailed guidelines regarding assembly, please refer to the provided instructions.

Types and Variants

There exists a broad range of cutting rings and mating styles, including swivel nuts, tube nipples, and hose ends, which can replace the cutting ring for sealing purposes. Unlike traditional designs, these modern configurations do away with the need for assembly that involves torquing the tube nut due to the integration of the flare into the tubing or hose itself. Nevertheless, the consistent presence of the 24° fitting and nut design prevails throughout the various styles.

Pressure Classification

This tube fitting system, known as Bite-Type, DIN, or ISO-1, comes in three distinct pressure classes: LL for low pressure applications, L for medium pressure applications, and S for high pressure applications. For information regarding the working pressures associated with these components, please consult the following compatibility chart.

Identifying 24° DIN Tube Fittings

The initial step in identification is to find a size and series code marked on the nut. It might display notations such as LL-08, 18-L, S20, etc. Once you have identified these details, refer to the Compatibility Chart for related components including cutting rings, caps, and plugs. It's important to note that not all manufacturers include this information on the nut itself, so additional steps may be necessary for proper identification.

Conducting Manual Size & Series Identification

In cases where the nut lacks sizing information, measuring the outer diameter (O.D) of the tube or the inner diameter (I.D) of the receptacle using calipers is the next step. Ensure the calipers are set to millimeters, as this measurement unit is standard for Metric tube fittings. Record this measurement for future reference.

Verifying Compatibility: Fitting & Components

Finally, cross-check your measurements against the Component Compatibility Chart to confirm the size and series. For instance, if the thread O.D is 22mm with a pitch of 1.5mm, and the tube size is recorded as 15mm, you would find that this combination corresponds to the L series for medium pressure, specifically L15 according to the chart. Verify your tube size, as some thread sizes can overlap between pressure series.

Assembling 24° DIN Tube Fittings

1. Cut the tube to the appropriate length and ensure it is deburred and cleaned.
2. Next, initiate the bite of the cutting ring into the tube, which can be done manually or with a hydraulic pre-set machine, especially for sizes larger than 18mm.
3. Perform an inspection after pre-setting to confirm the cutting ring is properly installed.
4. Finally, install the complete assembly.