CPV before control valve
CPV before control valve
(OP)
LS,
We have a system in which 2 fluids (A and B) are blended together. A is the main flow to which B is added with a control valve (pneumatic with positioner). The system runs without pump, but the driving force is gravity (tanks are 50 metres higher). As flow and pressure are fluctuating, someone suggested to install a constant pressure valve (constant pressure on the outlet of the CPV towards the control valve).
Can someone tell me what influence we can expect on the stability of the control valve? Will both valves be influencing eachother?
Thanks,
DYV
We have a system in which 2 fluids (A and B) are blended together. A is the main flow to which B is added with a control valve (pneumatic with positioner). The system runs without pump, but the driving force is gravity (tanks are 50 metres higher). As flow and pressure are fluctuating, someone suggested to install a constant pressure valve (constant pressure on the outlet of the CPV towards the control valve).
Can someone tell me what influence we can expect on the stability of the control valve? Will both valves be influencing eachother?
Thanks,
DYV





RE: CPV before control valve
Why/How does the pressure variation (from liquid level in the tanks?) adversely affect mixing these two products now?
How do you control the amount of B mixing with A now? In other words, what signal positions CPV's positioner, pressure, flow rate, color, temperature, and where is that being measured? At tank B or downstream of the A & B junction point?
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RE: CPV before control valve
The situation now is without the CPV, and the pneumatic control valve (equalpercentage, parabolic plug) is used for controling the blended product. This is initially done on ratio (by measuring both flows), and after a defined period the ratio is adjusted by a viscosity control of the blended product.
Problem is that pressure in B has to stay higher than pressure in A. Due to pressure fluctuations in B, we now have problems in keeping the control stable.
So my question was, what will be the influence of a CPV, when it is installed before the control valve.
RE: CPV before control valve
Regards
StoneCold
RE: CPV before control valve
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"What gets us into trouble is not what we don't know, its what we know for sure" - Mark Twain