Checking the Operability on the Crimped Fitting by Measuring the Reduction on the Nipple Diameter VWN VS 1.2

The inner nipple diameter is reduced by the compression on the inner and outer rubber shell, resulting from the crimping force. The nominal length of the nipple is decivise for the selection of the test mandrel.

Correct use of the test mandrel DORNVOS and the resulting potential change of the inside nipple diameter:

Fig. 1.
The inside nipple diameter is reduced excessively in the sealing zone through the crimp dimension, which is too tight.
ATTENTION: This crimped fitting is not functional. This error might result in premature failure on the hose line. The crimp diameter must be increased by several tenths of a millimeter!

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 Fig. 1. Excessive crimping, maximum reduction of the nipple diameter exceeded
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Fig. 2.
This illustration shows the maximum permissible reduction of the inside nipple. The crimp diameter should not be reduced any further, since otherwise there might be the risk of a premature failure on the hose line!

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 Fig. 2. Maximum reduction of the nipple diameter reached
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Fig. 3.
The perfect reduction of the nipple diameter has been reached. The crimp diameter should not be changed any more. It must, however, be checked prior to any change of the hose batch. The reached crimp dimension will correspond to the standard crimp dimensions as determinated from the press dimension table.

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 Fig. 3. Ideal reduction of the nipple diameter
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Fig. 4.
This illustration shows the minimum permissible reduction an the inside nipple diameter. In this case, it is still possible to reduce the crimping diameter by a few tenth of a millimeter!

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 Fig. 4. Minimum reduction of the nipple diameter
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Fig. 5.
Crimping did not cause any reduction of the inside nipple diameter. The crimping diameter is too large.
ATTENTION: This crimped fitting is not functional. There is a risk of a leak or of the hose slipping off the crimped fitting. It is necessary to decrease the crimping diameter by several tenths of a millimeter!

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 Fig. 5. No reduction of the nipple diameter
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Applicable standards:

| DIN 3852 | EN 853 | EN 856 |
| DIN 3859 | EN 854 | EN 857 |
| DIN 20 066 | EN 855 | EN 982 |