Valves with Intercept

[Irrigator]

Hi everybody.

I don’t know the meaning of “valves with intercept” (Headloss equation Intercept (C) Who could help me?

Thanks a lot. Irrigator

[Dan Crosby]

Hi Irrigator,

The headloss equation for valves is in the form:

H = KQⁿ + C


• H = headloss
  
• Q = flow
• K = constant
• n = index
• C = intercept

The intercept C represents any headloss in the valve assembly that is not dependent on the flow through the valve. It can be used to introduce a fixed amount of headloss through the valve, but typically there is no flow-independent component to the headloss, and C is zero. However, if you are trying to produce a headloss equation from experimental data, you may find that the curve fits better if an intercept is used. In practice this should not be a problem, provided the valve is only used in flow regimes that are 'on the curve'.

[jovivier]

The intercept can represent a start-up head required, eg if a valve requires a certain upstream pressure before it will open and the curve cuts the Y-axis instead of going through 0,0.

[Irrigator]

Fine Dan. Thanks a lot.
Irrigator

Hi Irrigator,

The headloss equation for valves is in the form:

H = KQⁿ + C


• H = headloss
  
• Q = flow
• K = constant
• n = index
• C = intercept

The intercept C represents any headloss in the valve assembly that is not dependent on the flow through the valve. It can be used to introduce a fixed amount of headloss through the valve, but typically there is no flow-independent component to the headloss, and C is zero. However, if you are trying to produce a headloss equation from experimental data, you may find that the curve fits better if an intercept is used. In practice this should not be a problem, provided the valve is only used in flow regimes that are 'on the curve'.