On our forum I was posting about the VCCM equation and the formula. One of the forum members came up with an interesting example.

The flow constant for the valve is:

\[

{K}_{vpl}=\frac {100lpm }{ \sqrt {35bar} }

\]

I give up. It doesn't work when I cut and paste using the Daum equation editor

Kvpl=100lpm/sqrt(35bar)

The VCCM equation is:

\[

v_{ss}=K_{vpl}\sqrt{\frac{P_{s}\cdot A_{pe}-F_{l}}{A_{pe}^{3}\cdot(1+\frac{\rho_{v}^{2}}{\rho_ {c}^{3}})}}

\]

The user calculated correctly that \[{v}_{ss}=259.7 \frac{mm}{s}\]

however this doesn't make sense because this is faster than the the flow makes it go equation that doesn't even take into account opposing force.

\[v=Q/A=212.2\frac{mm}{s}\]

How can this be?

To keep thing simple I chose the following system parameters

Cylinder 100mm diameter bore / 56mm rod.

System Pressure 70 bar

Valve - same as your example above.

Opposing force 500 N

System Pressure 70 bar

Valve - same as your example above.

Opposing force 500 N

\[

{K}_{vpl}=\frac {100lpm }{ \sqrt {35bar} }

\]

I give up. It doesn't work when I cut and paste using the Daum equation editor

Kvpl=100lpm/sqrt(35bar)

The VCCM equation is:

\[

v_{ss}=K_{vpl}\sqrt{\frac{P_{s}\cdot A_{pe}-F_{l}}{A_{pe}^{3}\cdot(1+\frac{\rho_{v}^{2}}{\rho_ {c}^{3}})}}

\]

The user calculated correctly that \[{v}_{ss}=259.7 \frac{mm}{s}\]

however this doesn't make sense because this is faster than the the flow makes it go equation that doesn't even take into account opposing force.

\[v=Q/A=212.2\frac{mm}{s}\]

How can this be?

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