Hose Size Selection Nomograph
To Use This Nomograph / A Further Example:
The length of a Hose Assembly can be measured in three ways:
- Pick the two known values.
- Lay a straightedge to intersect the two values.
- Intersection on the third vertical line gives the value of that factor.
To find the bore size for a Pressure Line consistent with a Flow Rate of 100 litres per minute (26 US or 22 Imperial gallons per minute), and a Flow Velocity of 4,5 metres per second (14.8 feet per second), connect Flow Rate to Flow Velocity and read Hose Bore on centre scale.
The line crosses Hose Bore between -12 and -16 on “All Other Dash Sizes” side of Hose Bore axis, so a -16 hose is required. If RQP5 or T5 Hose is to be used, for this example -16 would also be required.
The velocity of the fluid should not exceed the range shown in the right hand column.
When oil velocities are higher than recommended in the chart, turbulent flow occurs, resulting in loss of pressure and excessive heating.
For long hoses and/or high viscosity oil, or if the flow of hydraulic fluid is continuous, it is recommended to use figures at the lower end of the Maximum Recommended Velocity range.
A further example will help you to use this chart:
Locate the flow, 40 litres per minute (left hand column), and velocity, 15 feet per second (right hand column), since 15 is the centre of the Pressure Lines Maximum recommended velocity range.
Lay a straight edge across these two points. The straight edge crosses the centre column just above the -08 on “All Other Dash Sizes” side of Hose Bore axis.
Keeping the straight edge on 40 litres per minute, cross the centre column at -08 and -10 sizes and read the Flow Velocity in the right hand column.
It can be seen that using -08 Hose Size , Flow Velocity will be 18 feet per second, and for -10 Hose Size, Flow Velocity will be 11 feet per second. As the flow is continuous, -10 Hose Size is recommended.