Calibration Question

Why would you do that? It makes absolutely no sense.

Why do you not follow the calibration procedure of the manufacturer?

"swapped zero and span gas each other due to some reason" ?????????? You don't know why?

You obviously are not calibrating the equipment properly.

<Shakes head; palm slaps self; wonders how such nonsense can happen; unsubscribes in disgust>

This kind of a question cannot be accurately answered here. This question can only be answered by the manufacturer of the instrument and they may not tell you the answer. You see, unlike ABB, we have no idea what physical process their instrument uses to identify the gas quantities and ratios. We also do not know the quality of your procedural methods. We know that you believe that you did the testing correctly but we do not know if you actually did it correctly. For all we know this calibration routine might be needed only when very high resolution measurements are needed and you're not looking at high resolution results.

In this case ,

span is made as 0% ie no span for test sample and 21% is made as zero level ( minimum proportion ) .

Means that analyser demands min. 21% in test sample with 0% span range .

All of our calibration certifications are done by third party by out state's regulations. Agree best bet talk to manufacturer or a third party that calibrates and repairs that particular piece of equipment.

u have written due to some reason zero and span gas interchanged

it can also possible u haven't saved parameter at the end of calibration completion

o2 analyzer is still under working condition of previous calibration not this uproperly done calibration

I haven't seen a manual of ABB make o2 analyzer but if it is possible to check history parameter s of o2 analyzer which can show last calibration date and time

if inbuilt facility of history parameter check is available

[p| if u have provided 21% gas as zero and 0% gas as span

and u have set display range as 0 to 100%

if ur director is detecting 20% o2 u must get -95.23% at display a negative reading

"u" is not a word.

It is "you".

This is an engineering forum, not a teen text forum.

ok SIR I will kept in mind not to use "u" for you

infront of you I am like teen with not much knowledge compared to you

using small screen mobile keypad writing is so difficult thats why

OK, that explains it.

Never mind.

In the days in which I calibrated oxygen analysers for physiological experiments, we were taught why you do things as well as how you do them. The philosophy was something like this. You have an oxygen transducer with a linear output. Calibration at two points is the equivalent of establishing the coordinates of two points on the line and solving simultaneous equations. In theory you could put either point in first. However, on the machines that we used we had a knob which set the zero first. The second knob in effect adjusted the gain (slope of the equation) in order to set the second point. If you used the second knob first, and the zero was out of adjustment, you set the wrong slope, and you made matters worse by then setting the zero. If you use the wrong gas, which is what I think you are implying, you set a negative slope, which is impossible. Our analyser electronics were analogue, but I assume that modern equipment is digital and would simply refuse to recognise the calibration.

There is a further aspect to this, in that the accuracy of the calibration is improved by having the calibration points as far apart as possible. If your analysis involves concentrations above 21% and you want more accurate results then the correct second calibration gas is not air but 100% oxygen. In our lab, as I remember, we reckoned that air was not 21% but 20.93%. Medical oxygen is at least 99.5%. Industrial and research oxygens may be of even higher purity (up to 99.9999%).

Don't be a cheapskate, spend the money on the calibration gases, and do over. Your instrument may be fooling you into thinking the response is correct when if fact, there is no change in response when the sample is changing. Make sure you follow the calibration procedure exactly as specified in the manuals in the future, and then test the calibration with a known sample less than the span.

You can check your calibration by applying your span and Zero gases, to confirm what you have done is what you think.If zero gas reads 0 then you did not calibrate the instument the way you think.