Determination of Hydraulic Hose Length

Determination of Hydraulic Hose Length

Many hydraulic hose installers are not trained to measure and determine hose length accurately. Therefore, the replacement hose may stay slightly shorter or slightly longer than the original part. Where centimeters are important, confusion about measuring hose lengths accurately can cause delays and additional costs.
When requesting a Hydraulic hose assembly, length is generally defined in two ways: total length or cut length. Total length is the most common way to describe hose length and is often used when ordering Hidroman and Hansaflex hydraulic hoses.

Total Length of Hose Assembly
When installing Hydraulic Hose, it is important to identify where the "Total Hose Length" (THU) is critical. In many industrial applications (water or general purpose) THU is not critical. However, THU can be very important in many hydraulic applications due to space constraints. The THU of a hose assembly can be determined by measuring the hose assembly end-to-end.

Examples showing standard hose installation lengths for straight nozzle, 90º nozzle, and 45 hortum nozzle are provided on the side. When calculating THU it is important to keep in mind the following:

For heads with male threads, the length is measured from the end of the heads.
Female heads and flanged heads are measured from the sealing surfaces.
Angled heads are measured from the center of the sealing surface.

Hose Cut Length
Hydraulic Hose cut length is determined based on specifications. The hose cut length of a hydraulic hose assembly is calculated by subtracting the cut factor (distance from the bottom of the nozzle or sleeve to the end of the fitting or an inner sealing surface). In the example below, pay special attention to the "B" dimension. Knowing the total length of the desired hose assembly, subtract dimension "B" from the total length for each fitting to obtain the hose cut length.

Important Factors to Define Hose Length
You can define the assembled hydraulic hose length using THU or Hose Cut Length, but keep in mind that the length will vary by expansion or contraction under pressure (typically between 2% and 4%). Other factors worth considering are:

Consider machine vibration and movement as well as hydraulic hose design.
Allow enough length for the fittings to avoid pulling force when the parts reach their limits of travel.
Avoid leaving hoses taut so as not to restrict fluid transfer.
When working under pressure, avoid fixing the bend sections to cause length variation.
Do not clamp high and low pressure lines together.
When replacing tubing, cut the new tubing to the same length as the original tubing.
If the new hose is too short, it may cause a decrease in its service life due to stress / shrinkage under pressure.