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VRBASGRAD
December 14th, 2006, 10:11 AM
I am using Pressure Sensor 4-20mA and at 10 PSI my multimeter is showing me 5,6mA.I just want to know if this is rite, can somebody please tell me how to calculate this.

thx

10BaseT.
December 14th, 2006, 10:19 AM
I don't know - what colour is it ?

Seriously , you are asking an open ended question- what you state suggests that this is a 100 PSI transducer
((20-4)/(5.5-4))*10 (I hope I got that right after the beautiful essay posted here about this very subject)

But I could be completely wrong - unless I know two points , I can't extrapolate ( put a line) through your data .
This transducer could be 8-20 PSI , and I would be none the wiser without either you reading what it has stamped on the body , or posting a few more readings .

VRBASGRAD
December 14th, 2006, 10:29 AM
Transducer is from 0 to 100 psi.This is old device; I just want to know if it still works. There is no information except range from 0 to 100 PSI.I want to see at different pressure settings what the output is.

10BaseT.
December 14th, 2006, 10:43 AM
well , if you take the span of a 4-20mA signal , you have 16mA , let us divide this 16 into the span of your device (100 PSI) and we should get the ratio :- 100PSI/16mA= 6.25PSI/mA - now you said that your device gave an output of 5.6 mA at 10PSI lets see if this is OK :-

(5.6mA-4mA)*6.25 = 1.6*6.25 = 10

I reckon that is OK then , but you may want to stick a few more PSI up its kilt and make sure that it is reasonably linear .

VRBASGRAD
December 14th, 2006, 11:21 AM
well , if you take the span of a 4-20mA signal , you have 16mA , let us divide this 16 into the span of your device (100 PSI) and we should get the ratio :- 100PSI/16mA= 6.25PSI/mA - now you said that your device gave an output of 5.6 mA at 10PSI lets see if this is OK :-

(5.6mA-4mA)*6.25 = 1.6*6.25 = 10

I reckon that is OK then , but you may want to stick a few more PSI up its kilt and make sure that it is reasonably linear .


Thanks

DJM
December 14th, 2006, 01:25 PM
For more info on how to quickly solve these problems, look here.

http://www.plctalk.net/qanda/showthread.php?t=15069

You'll be glad you did!

Tom Jenkins
December 14th, 2006, 07:35 PM
Here are some simple examples.