14
Selection from Viscosity Characteristic Graph
Required specification example: Find the pilot air pressure for a discharge rate of 2.7 L/min,
discharge pressure of 0.25 MPa and a viscosity of 100 mPa·s.
Selection procedures:
1. First find the ratio of the discharge rate for fresh water when viscosity is 100 mPa·s from the
graph below. It is determined to be 45%.
2. Next, in the required specification example, the viscosity is 100 mPa·s and the discharge rate is
2.7 L/min. Since this is equivalent to 45% of the discharge rate for fresh water, 2.7 L/min ÷ 0.45 =
6 L/min, indicating that a discharge rate of 6 L/min is required for fresh water.
3. Finally, find the pilot air pressure and pilot air consumption based on selection from the flow
characteristic graphs.
Caution
Viscosities up to 1000 mPa·s can be used.
Viscosity and dynamic viscosity are obtained by the formulas below.
Dynamic viscosit
y ν[m
2
/s]
＝
Viscosity μ[Pa
･
s]
Density ρ[kg/m
3
]
Formulas below can be used for common units
- 1cP = 1mPa
･
s = 10
-3
Pa
･
s
- 1cSt = 1mm
2
/s = 10
-6
m
2
/s
3) Viscosity Characteristics
(Flow rate correction for viscous fluids)
