Answer / malaini

Manivannan answer is Linear curve. For equal percentage
every equal control valve opening will give equal
percentage incremental of flow rate. Tq

Answer / shyam

Through control valve flow characteristic ( cv )
we calculate flow rate at inlet & outlet pressure of
control valve.

Answer / k.surya mutyalaro

each increment in valve lift increases the flowrate by a
certain percentage of the previous flow. The relationship
between valve lift and orifice size (and therefore flowrate)
is not linear

but it is depends on Valve rangeability (ratio of the
maximum to minimum controllable flowrate)

v(h)=((e power x)/t) * Vmax



V(h)=
Volumetric flow through the valve at lift H.
x
=
(ln t) H Note: 'In' is a mathematical function known as
'natural logarithm'.

t
=
Valve rangeability
H
=
Valve lift (0 = closed, 1 = fully open)
max
=
Maximum volumetric flow through the valve

it is very important that the Valve rangeability defers
from the valve to valve.

Answer / www.islamqa.com

x-axis is %valve stroke
y-axis is %flow rate

we have 3 versatile characteristics:
====================================
linear: flow rate is linearly proportional with valve stroke
equal percentage: flow rate increases slowly with valve
stroke
quick opening: flow rate is increasing dramatically with
small valve stroke


Regards,

Ahmed Sabry
Control and Instrumentation Engineer
GPC - General Petroleum Company
CELL.: 00 2 0121367310

Answer / manivannan

x-axis controller output;y-axis stem position graph is
linear curve

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