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Model 212 Trace Thermal Conductivity Analyzer

The zero adjustment on my 212 is not working. What do I do?
How do I balance the bridge on the 212R?
How do I purge the zero/reference gas on the 212R?
What things should be considered in using the 212R to measure H2 or other compounds in H2?
What is the steady state current consumption from mains?


The zero adjustment on my 212 is not working. What do I do?

A procedure to troubleshoot this issue can be found by downloading this PDF file.


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How do I balance the bridge on the 212R?

The analyzer is very sensitive to temperature if the front panel is open, therefore this should be avoided. If, however, it must be opened, the analyzer should run at least 6 hours or overnight before attempting to do any bridge balancing and calibration.

1- Introduce zero gas; wait for 10 minutes or until the analyzer reading has stabilized. Position the range switch to X1 range.

2- Open the small window cover of the potentiometers; adjust the reactive potentiometer (Pot) one way and then the other way, watching the analyzer reading until it reaches its smallest value. This is potentiometer P2.

Note: When adjusting the reactive pot the same direction and the reading decreases to the smallest value, then the reading will start increasing again.

3- Repeat the same procedure in step 2 for resistive pot. This is potentiometer P1.

4- Adjust zero pot so the analyzer reading is zero.

5- Introduce span gas; let it run for 10 minutes and then adjust span pot so the analyzer reading gives the span gas concentration.

Note: When the span gas is introduced to the analyzer, the reading should go positive. If the reading goes negative at first, then positive, adjust the zero pot so the analyzer reading is zero. (Note: If the reading even goes negative 1 or 2 ppm, it could reduce analyzer sensitivity more than 20 percent of full scale). Introduce zero gas again, then re-adjust resistive pot so the analyzer reading goes positive (to the same value as the analyzer going negative).

Example: When introducing span gas to the analyzer, the reading goes from zero to negative 10 ppm, and then goes positive. At this time introduce the zero gas again, wait for the reading to stabilize, and adjust the resistive pot so the analyzer reads +10 ppm. Repeat step 5.


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How do I purge the zero/reference gas on the 212R?

A procedure to troubleshoot this issue can be found by downloading this PDF file.


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What things should be considered in using the 212R to measure H2 or other compounds in H2?

H2 in the gaseous state can be assumed to be one of two states, para H2 or ortho H2. Each has its own Thermal Conductivity Value. These differ by about 10% from one another.

This must be taken into consideration when attempting to use the 212R on H2 streams.

We would recommend one consult Wikipedia or other sources to learn more about these two states of H2 and how the thermal conductivity of the gas stream varies with the state.

If for instance one is using pure H2 as a reference gas, and this gas is in the para state associated with cryogenic H2 recently vaporized, and this is then compared to cylinder H2 which may be in a different state, then considerable measurement errors can result.

Plase contact Teledyne for further guidance or information on your specific application.


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What is the steady state current consumption from mains?

With the 110 VAC configuration, it is 1.2 A


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