6750 FAQ

When we do a SPAN calibration for S/N : 1260 at 2000ppm with standard solution, we noticed that the readings are unable to maintain or achieve at 2000ppm. The reading will go up to about 1700ppm and start dropping to about 400ppm although the standard solution is 2000ppm. But when we sample directly from the 2000ppm standard solution, readings are stable at 1980ppm. Please advise what is the cause and how to resolve it.

When we suspend the analyzer or when we quit the program (back to Windows), we are unable to restart the software and can only do so by turning off and on the power supply. Is that correct?

What should the IR values be when sampling? We are getting about 20000 when sampling the 2000ppm standard solution and when sampling DI water, it will slowly decrease to about 470. Is this correct?

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Q: ​When we do a SPAN calibration for S/N : 1260 at 2000ppm with standard solution, we noticed that the readings are unable to maintain or achieve at 2000ppm. The reading will go up to about 1700ppm and start dropping to about 400ppm although the standard solution is 2000ppm. But when we sample directly from the 2000ppm standard solution, readings are stable at 1980ppm. Please advise what is the cause and how to resolve it. ​

A: Based on question four also, the IR is out of calibration. Rezero the IR with zero gas and Respan the ir with 1%CO2 gas. The analyzer will then need to be liquid calibrated. Perform a liquid zero when the reading is stable and take note of the IR reading (which should be less than 1000). Perform a liquid span when the reading is stable and take note of the IR reading (which will probably be between 8000 and 11000). 

If the analyzer does not maintain span when in calibration, but does when running sample, verify there are no leaks in the autocal valve system. (Either liquid leaking out or air bubbles leaking into the tubing. Another test would be to have span gas go directly to the IR and see if TOC readings fluctuate. ​

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Q: ​When we suspend the analyzer or when we quit the program (back to Windows), we are unable to restart the software and can only do so by turning off and on the power supply. Is that correct? ​

A: Yes, that is normal. If the software is exited, the entire analyzer will need to be rebooted by cycling the power. ​

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Q: ​What should the IR values be when sampling? We are getting about 20000 when sampling the 2000ppm standard solution and when sampling DI water, it will slowly decrease to about 470. Is this c​orrect? ​

A: The IR reading should not go much over 10000 when running 2000ppm. If it does, either the IR needs calibration (zero and 1.0% span) or there may be a problem with the standard solution. ​

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