Calgary, Alberta, Canada dzyanis@engineer.com

Fluid Power Pro

Hose Overall Assembly Length

There are three different ways to measure hose assembly length are used in the practice:

  1. Use value of “Overall length” (Default for Parker’s suppliers)
  2. Use value of “Seat-to-seat length” (Default for RYCO’s suppliers)
  3. Use value of “Cut length” (Default for EATON suppliers)

 

Unfortunately, there are no any standards for the definition of  “Overall Length” value and therefore different manufactures determine different ways of measuring the value of Overall Length. This is why you need to be very careful before ordering hoses with new supplier and you have to specify which length you provide, because sometimes it can be critical.

The normal practice of “Overall Length” measuring please see below:

All US fittings (JIC, SAE, NPSM), except ORFS fittings, are measured up to the end of the nut:

US fittings

DIN, BSP and ORFS fittings are measured up to the end of the sealing head (this rule does not work with RYCO suppliers, but works with Parker and EATON suppliers):

ORFS fittings

SAE flange fittings are measured up to the face:

SAE flange fittings

All male threads are measured up to the end of the fittings:

male threads

All 90 degree fittings are measured to the head center line:

90* fittings

Other elbow fittings can be measured up to the center line of the head face (RYCO) or up to the center line of the seal face (Parker):

0..90* fittings

I recommend to use Parker’s rule for this type of fittings.

And my last recommendation: check the value of Overall Assembly length: it has not to be less than Minimum Overall ASSY Length:

If the Overall Length is not long enough it could hinder the ability of the hose assembly to function properly. Notes from RYCO:

This is particularly the case when utilising very short hose assemblies, where a shortening or shrinkage of the hose under pressure may result in hose and coupling separation. In addition, small misalignments, vibration and other displacements may induce very high stresses upon the hose/coupling juncture, as there is little capacity for the flexible nature of the hose to compensate.

Parameters “A” and “B” you can take from manufacturer’s catalog.

Sources:

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