Control valve can not be without positioner. The purpose of
the positioner is to control the control valve stroke so as
to keep the valve in desired position. The positioner
receives signal from the controller, and send the boosted
signal to the actuator to reach the desired position as and
when the valve reaches the desired position the positioner
cuts the boosted signal to the actuator and keeps the
position.
Yes we can use a control valve without positioner.
We can use electro-pneumatic transducer.The transducer
receives a direct current input signal and uses a torque
motor, nozzle-flapper,and pneumatic relay to convert the
electric signal to a proportional pneumatic output signal.
YES, ABSOLUTELYU. WE CAN USE CONTROL VALVE W/O POSSITIONER.
BASICALLY POSSITIONER IS USED FOR QUICK OPERATION OF
CONTROL VALVE. FOR AN EXAMPLE: IF CONTROL VALVE OPERATING
RANGE IS 0.6 TO 2.6 KG/CM2, AT THAT TIME POSSIOTIONER IS
USED FOR AMPLIFICATION FOR THE HIGH PRESSURE CONTROL VALVE
EVEN IF INPUT PRESSURE IS 0.2 TO 1.0 KG/CM2.
Yes, We can use control valve without a positioner. The
basic purpose of positioner is to supply required punemetic
air w.r.t 4-20 mA standard signal, you can say for example
3.2 kg/cm2 to 4 kg/cm2. and it also checks for the
appropriate vavle opening(feedback) and stops air supply
going to valve actuator.
Without Positiner we can use control valve,but we must have
i/p converter, which generally converts 4-20 mA signal to
0.2 -1 kg/cm2, so in that case valve will not opearate
fully . but it will opearate upto certain level.
So when positoner got fail and we dont have new one, and if
we require valve to be controlled upto certain level, we
can use i/p converter,
Yes, it can be used without positioner with the following
condition.
(1) Spring operating range should be 0.2 to 1.0 Kg/Cm2.
(2) If the application of the control valve for the
relevant process parameter control is not critical, the
valve can work without positioner i.e. it will give less
accurate output & control of parameter.
Yes we can operate a control without a positioner in the
following condiotions.
1) Volume booster is not required.
2) Operation of control valve will be very sluggish.
3) Charecteristics of control valve cannot be changed.
4) If the valve is self regulation than also positioner is
not required.
There are yes and no answers of this query.
correct answer is Yes. Most of the answers are Yes but
Explanation is a bit not clear. Yes offcource valve
positioner has lot of usages and advantages in controling
the valve position.
Answer no 8 is some what clear.
Here is the straight right answer.
"Yes we can use a control valve with out positioner when
bench set of the control valve is matching with the
standard bench set of the valves." ie, valve spring range
is 0.2 kg - 1 kg. where the process fluid is clean, and for
the valve sizes below 1 inch usually.
Where these valves need regular preventive maintanence
(lubricating and changing the packings promptly or else
these valse will give erratic positions).
generally for transmitter we are giving supply 24vlts?but we
are getting output 4-20ma ? how it is possible? is there any
operation inside the tx?pls give complete information?
A pressure differential gauge type of instrument has a
manifold with 2 isolation valves (hp and lp),2 vents(1 each
for hp and lp) and 1 equalizing valve. Determine the
position of each valve(either fully closed or fully open)
when troboulshooting to:
1. zero the transmitter.
2. determine if there is a block in the impulse line.
3. determine if the gauge is functioning properly.
The process fluid is water.
Please anyone answer my question, what is the difference
between single acting and double acting control valve, in
what condition we better choose single acting rather than
double acting
To Refer this Site to Your Friends 
Site Map
