Page 91 - Fluid Power Engineering

66 Cha pte r T h ree

Flow rate (L /min)

FIGURE 3.5 Nomogram for the calculation of the hose diameter.

The recommended mean fluid velocity in flexible hoses is actu-
ally within 2.1 to 4.6 m/s for the pressure line and 0.6 to 1.2 m/s for
the suction, return, and low pressure lines.
The hose diameter can be also calculated by using the nomogram
shown in Fig. 3.5. Figure 3.6 gives some advice and hints about the
right and wrong hose mounting.
Table 3.2 shows the typical constructional and operational param-
eters of high-pressure hydraulic hoses. The hose is built from the fol-
lowing layers, which insure the required stiffness and reliability of
operation:

1. Inner synthetic rubber tube, resistant to oils and hydrocar-
ο ο
bons. The operating temperature ranges from 40 C to 120 C
and the hose may have an internal dressing layer of Viton.
2. High-abrasion-resistant metallic screen layers.
3. Closely braided high tensile steel wire layers separated by
antifriction rubber layer.
4. Abrasion resistant synthetic rubber cover.
5. Textile layer.