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Differential Pressure Transmitter

01/17/2012 11:35 PM

Hi every body, cn help me. Cn explain me what's calibration procedure of dp transmitter. Thank you.

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Guru
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#1

Re: Differential pressure transmitter

01/18/2012 4:18 AM

Take it to the facility's instrument workshop, together with its factory calibration certificate, and ask the technician there to repeat the test.

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Guru

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#2

Re: Differential pressure transmitter

01/18/2012 4:58 AM

The, "calibration procedure of dp transmitter" will be whatever is recommended by the maker of same, which you have not bothered to supply.

Or, do as PWSlack has suggested.

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#3

Re: Differential Pressure Transmitter

01/18/2012 11:08 AM

Use a manometer

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#4

Re: Differential Pressure Transmitter

01/18/2012 6:49 PM

OK, It really depends on the calibrated range of the instrument. but the procedure is fairly simple if you have the right equipment. if the range is in a positive scale i.e; 0-100 Kpa. Then ensure both the high and low pressure cells of the TX are at atmospheric pressure. check that the output of the instrument is properly zeroed. output should be 4mA or 20 Kpa or 3PSI, depending on the type of instrument. Then apply 100 Kpa to the "high" pressure cell. checking output of the instrument at 25% FSD increments. This is to ensure the instrument has good linearity. The outputs should be 4,8,12,16,20 mA for 0,25,50,75,100 % respectively. Then decrease the applied pressure back through the range to check for hysteresis and repeatability of the instrument. If there is any discrepancies at 0 or 100% FSD the output can be adjusted by means of a zero and span screw or by HART protocol or several other means, again it really depends on the type of instrument. Just remember zero the output first as any changes to the zero will generally effect the span. If you give me the details of the TX, I can give you a more helpful procedure. Best of luck!

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Power-User
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#5

Re: Differential Pressure Transmitter

03/17/2012 8:46 AM

You can calibrate it using a pressure calibrator to provide the pressure and use a miiliampere measuring instrument to check what is the correspoding output.

For example if the output of your transmitter is 4 to 20mA and the range of the transmitter is 0 to 100 Bar, for 0 Bar pressure output current should be 4mA.

For 25 Bar pressure, output current should be 8mA.

For 50 Bar pressure, output current should be 12mA.

For 75 Bar pressure, output current should be 16mA.

For 100 Bar pressure, output current should be 20mA.

After this you have to calibrate your indicator also. Use a loop calibrator to provide milliampere output and check the indication in the digital indicator.

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