Answer / mahesh bajaj

The transducers are calibrated against reference standards
which are atleast 10 times more accurate then the transducer
to be calibrated.

Let me elaborate by giving an example.

Orifice plate infers flow rate by measuring differential
pressure.so to calibrate orifice plate, reference standard
say magnetic flowmeter is used which measures flow rate.say
flow range is 0-100 lpm and at every 10 lpm, differential
pressure across orifice is measured and constant is evolved
between flow rate and differential pressure. This constant
is also known as discharge coefficient or calibration
constant and one dimensional bernolli's equation is used to
compute this constant.
Now once you know the constant the orifice flow element is
ready to be used in any line size without using any
reference standard.

Hope this helps.

why does a transmitter o/o signal starts from 3-15psi or 4- 20mA?

11 Answers  

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I was working on calibrating turbidity transmitters endress+hauser at effluent polishing plant.We calibrated using NTU buffers.What happened is that when we immersed the sensor, everytime we raise and lower the sensor gradually, the reading will vary.my question is that is there any specifications on what is the required distance from the bottom of the container with buffer to the face of the sensor?Is it ok to install the sensor in a medium which has turbulence specially if bubbles are present?

0 Answers  

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what are the possible reasons if a control valve fails to open/close?

1 Answers   DEWA,

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Q1: Consider part of a control loop, which excludes the transmitter, consisting of a process, a controller and a control valve which may be represented by two dead times of 0.5 min each and three exponential lags of 0.8 min., 1.0 min. and 1.5 min. respectively. We wish to express this system as an overall first order plus dead time (FOPLD) model ie gain, time constant and process dead time. (We will see later that this is often done, to simplify controller tuning). For this exercise, gain is considered to be 1.0. (A) If the transmitter is a flow transmitter whose behaviour can be described by a dead time of 0.2 min. and an exponential lag of 0.5 min. in terms of the overall dead time and overall first order lag how can the system behaviour be approximated ? Overall dead time = Overall time constant = (B) If the transmitter is a temperature transmitter with a temperature sensor in a protecting well whose behaviour can be described by a dead time of 0.7 min. and an exponential lag of 15 min. how can the overall system behaviour be approximated now? Overall dead time = Overall time constant =

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can any one explain in which term we are flow flow is it volumetric r is it mass? and y

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How to Calibrate Coriolis Flow transmitter in field

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Explain the working of an electronic level troll.

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when placing a vent or drain hole on an orifice plate should you measure from the center of the bore up or down for the vent placement?

0 Answers  

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