Answer / gopalakrishnan.p

Yes there are two adjustments in transmitter and
positioners i.e ZERO and SPAN adjustment.

For example, if we calibrate the level transmitter for 4 to
20 mA with the range of 0 mmH2o to 5000 mmH20, for 0 mmH2o
we must get 4 mA and if it not 4 mA(say 4.5mA) means, we
start to adjust the zero adjustment to make 4 mA for 0
mmH2o.
And for 5000 mmH2o we must get 20 mA and if it not 20 mA
(say 19.69 mA) means, we start to adjust the span to 20 mA.
This is the way to calibrate the transmitter with the help
of zero and span adjustment.

Answer / dhanavel prakash

For transmitter
1)4MA value is Low range value(ie zero percentage)
2)20MA value is upper range value(ie 100 percentage)
3)but span means the difference between the LRV and URV

Example for span

if the range 0 to 100 the span is 100 and the zero value =0.
if the range -100 to 100 the span is 200 and the zero value=-100.

if ok press yes not ok press no

Answer / rakhi n

Above explained is zero adjustment of transmitter,
Span of transmitter is
say is above transmitter is of range 0 mmH2o to 5000 mmH20
than span of transmitter will be 5000 mmH2O
sometime we do have negative ranged tnansmitter like -20
bar to 20 bar in this case span willbe 40 bar.

Answer / ashish namdev, bina refinery [

The transmitter working with a range which feed by user
according process parameters.

The transmitter is a combination of primary sensor,
transducer, converters, signal conditioners etc. when
transmitter read any value that value sense by primary
sensor then convert into electronic form after then
filtering, sampling, conversion many process will to be done
for get output value. when these all process do then the
combination of all internal & external
hardware/software/electronics parts don't get
synchronization for any particular value at a time.
for remove these problems we set zero & span. that new
value create a new scale to read unknown value in
transmitter EROM memory portion. that new value will work as
URV & LRV for the transmitter.

Answer / y k patel

zero adjustment of any instrument simply means that the instrument shall show the minimum value on the scale against the standard minimum value.

Range is simply URV-LRV

Answer / ahmed hamdy

As mentioned above
span is the difference between URV and LRV

Answer / ayub

Zero same meaning with LRV, but Span sometimes not only URV but Span is URV minus LRV, why because sometimes the range of a equipment its start from minus to positive.
eg: Range cal by designer -75 to 77 mmH2O
So, Zero or LRV is -75 mmH2O
But, Span or URV is 150 mmH2O, its come from URV - LRV

Answer / eng\ ahmed saleh

ZERO : Is The LRV "Lower Range Value" of the transmitter
SPAN : Is The URV "Upper Range Value" of the transmitter

why 4-20 mA signal is preferred over a 0-10V signal

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HELLO FRENDS ,, I M IN THE MIDST OF TROUBLE .. JUST LITTLE HELP ME... SUPPOSE ,, I HAVE A CLOSE VESSELE TANK ( HEXANE MEDIA ) ,, I M USING ROSEMOUNT 2051 DPT FOR LEVEL APPLICATION .. ITS CALIBRATE RANGE IS.. . 0 TO 950 MMH20 ..I DID CALIBRATED DPT WITHOUT REMOVING IMPULSE LINE OF HIGH AND LOW TAPPING.. & WITHOUT DISTURB 3 WAY MANIFOLD..!!! BUT ,,, DURING CALIBRATION I SELECT RANGE BY HART LRV IS 900 MMH20 & URV IS 1300 MMH20 ,, BUT ,TANK LEVEL SOMETIMES 100 % AT 1100 MMH20 , SOMETIMES 1300 MMH20 ..IN THIS CONDITION .. WHOLE LOOP FAILED ,, MAIN THING IS THAT ,, HOW TO CUSTOME RANGE SELECT ?? AND IF I USED RANGE OVER THE ORIGINAL CALIBRATE RANGE ,,,THEN WHAT ERROR WILL BE COME ??? HOW TO ZERO CALIBRATION OF DPT... HOW TO ZERO TRIM BY MANIFOLD ?? AND FOR TANK LEVEL PURPOSE ... WHICH UNIT I CAN USE ??? IS THERE ANY CALCULATION OR CALIBRATION .. IF YEH .. THEN PLZ JUST GIVE ME CALIBRATION STEPS FOR DPT.. THANKS YOURSSSSSSS

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