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Technical Support FAQ

311 Series - Portable Oxygen Analyzers

What is the self discharge rate of NiCad batteries?
We have a 311 analyzer equipped with a B-2C sensor. How selective is this sensor in distinguishing oxygen from other gases? How possible is it that we could be recording another gas as oxygen, and if so are there any likely candidates?
Recently we installed a new B-2C cell in our analyzer, and now we are experiencing problems.

We obtain erroneous readings, under zero or off-scale (like a negative concentration of oxygen). Then, after a few hours, it starts to read, but suddenly goes off-scale again. This is a cycle.

We are purging the analyzer continuously with nitrogen (N2: 99.999, O2 <2 ppm), and using a sampling manifold. We feed natural gas with a 2.60%mol of CO2 to the analyzer. We measure oxygen content in natural gas.

Is the class B-2C cell appropriate if we want to measure the oxygen content in a natural gas with a CO2 concentration of 2.60%mol (26000 ppm)? Our measurements are not continuous (2-3 per hour)

Should we use another class of cell?
I've been using you Model 311 for many years. Generally I use air for calibration.  Can I use Nitrogen with 3 ppm oxygen for calibration?
Will the 311TC function properly with trace amounts of hydrocarbon vapors present? At what concentration of hydrocarbons (C5 vapors) would we need to be concerned with the meter?
Can you go through the calibration setup for me?
How do I test my 311TC with the Teledyne O2 cell simulator?
What is the 311TC's lowest detection limit?
Would solids damage a Model 311 O2 analyzer sensor? Subject is a two phase flow system—gas with some polyethylene powders. Do we need to put a filter in between and what recommended filter would we use in the discharge extruder powder inlet system?
After replacing the battery on a 311TC analyzer we noticed that the indicator mark on the battery test is between 6 and 8 on the display. Charging it further does not increase the reading. Should the test for a fully charged battery be above 8 or is it enough for it to be between 6 and 8?
We are using a 311 with A-2C cell due to CO2 in the gas being sampled. When the analyzer is not in use, can we purge it with nitrogen?
Can the analyzer be calibrated on air?


What is the self discharge rate of NiCad batteries?

The rate of its capacity drop is approximately 10 days.

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We have a 311 analyzer equipped with a B-2C sensor. How selective is this sensor in distinguishing oxygen from other gases? How possible is it that we could be recording another gas as oxygen, and if so are there any likely candidates?

The B-2C sensor is specific to oxygen. However there are a few gases that may be seen by the sensor as oxygen.

Those would be strong oxidizing agents; agents that are as strong or stronger than oxygen such as the halogens Chlorine, Ozone, strong NO, Peroxide. etc.

Some interference is positive, like CL = 1:2, while others like CO are negative. For specific concerns and questions, don't hesitate to contact Teledyne at TETCI_customerservice@teledyne.com.

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Should we use another class of cell?

The B-2C sensor will not work for high CO2 levels. This will damage the sensor. You should use an A-2C sensor and purge the unit at all times with a similar level of CO2 when not in use.

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I've been using you Model 311 for many years. Generally I use air for calibration. Can I use Nitrogen with 3 ppm oxygen for calibration?

You can do this but we would not recommend it. We recommend using gases 8 ppm and above for calibration. We have found mixtures under this level are not reliable.

Also there is an offset from the sensor itself that will distort calibrations made in low single digit ppm levels.

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Will the 311TC function properly with trace amounts of hydrocarbon vapors present? At what concentration of hydrocarbons (C5 vapors) would we need to be concerned with the meter?

Non condensing Hydrocarbons are not an issue as far as the performance of the unit.

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Can you go through the calibration setup for me?

311 calibration setup:
• Place the span gas cylinder near the analyzer in an upright position in a secure location.
• Attach the pressure regulator to the cylinder.
• Attach the flow restrictor to the regulator (flat end).
• Attach a 1/4” to 1/8”reducer to the restrictor (open end).
• Attach the sample line to the restrictor using the union.
• Attach a 1/4” to 1/8” reducer to the end of the sample line.
• Attach a 311 quick release connector to the 1/4” reducer.

Purging calibration gear:
Prior to each use, the assembled calibration setup must be purged to remove air trapped in its various parts. This process will purge the system while minimizing both time and span gas use.
1. Do not terminate the calibration sample line at the analyzer end.
2. Momentarily crack open the span gas cylinder valve to pressurize the regulator and close the valve fully.
3. Allow the sample delivery set up to depressurize (about 4 seconds).
4. Repeat steps 2 and 3 at least five times.
5. Open the span gas cylinder valve fully.
6. The sample delivery system is now fully purged and ready for use.

Attaching the span gas and calibration:
When span gas is first delivered to the analyzer, it must be at a high flow rate because there will be air trapped in the analyzer’s span gas plumbing. This must be purged rapidly to allow the sensor to properly respond to the low levels of O2 in the span gas. Model 311 portable analyzers do not typically have sample systems that could trap air and therefore require only low (.2-1 SCFH) flow rates.

• With the sample gas flowing, attach it to the analyzer’s span gas inlet.
• Select the span gas with the calibration valve on the analyzer.
• Adjust the pressure regulator to set the analyzer to its maximum flow rate, or to full scale on the analyzer’s flowmeter.
• Allow the analyzer to purge at this high rate for 2 minutes or until its reading starts to approach the correct span value.
• Reduce the pressure and set the analyzer’s flow rate to its standard value (the sample flow rate used for the sample gas; 0.2 - .5 SCFH typical).
• At 4 minute intervals, note the analyzer’s reading to determine if it has stabilized.
• After the reading has been stable for a period of 4 minutes, record the current O2 reading and adjust the analyzer’s span to match the span gas O2 content.
• After 4 minutes to verify the span reading is stable and correct.
• Select the sample gas with the analyzer’s span valve.
• The analyzer is ready to return to service.
• Close the span gas valve prior to disassembling the calibration setup.


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How do I test my 311TC with the Teledyne O2 cell simulator?

1) Set analyzer: Turn the Range switch to the CAL position.

2) Set simulator: Turn the Selector switch to B2
Move Dial 1 & Dial 2 to fully clock-wise =000.
Turn the Attenuator to CAL

3) Connect the O2 Cell simulator to the analyzer's sensor contacts and test as follows:
  • Adjust the span pot on the analyzer until the Meter needle reaches the Cal Mark (20.9%). lock the span knob.
  • Switch the Attenuator to 1%. The needle goes down-scale.
  • Switch the Analyzer Range switch to X1000. The needle goes up to full-scale reading of 10,000 ppm.
  • Switch the Simulator Attenuator to 1000 ppm. The needle goes down-scale.
  • Switch the Range switch to X100. The needle goes up to full-scale reading or 1000 ppm.
  • Switch the Attenuator to 100 ppm. The needle goes down-scale.
  • Switch the Range switch to X10. The needle goes up to full-scale reading of 100 ppm.
  • Switch the Attenuator to 10 ppm. The needle goes down-scale.
  • Switch the Range switch to X1. The needle goes up to full-scale reading of 10 ppm.
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What is the 311TC's lowest detection limit?

The lower detection limit of this unit depends on which range it is used. If it is used on the 10ppm Full Scale Range, the LDL is 100ppb.

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Would solids damage a Model 311 O2 analyzer sensor? Subject is a two phase flow system—gas with some polyethylene powders. Do we need to put a filter in between and what recommended filter would we use in the discharge extruder powder inlet system?

It depends on discharge powder micron size. If the powder is very fine then it will be better to go for 1 micron or less to avoid contamination.

If particulate is the only concern then a metallic filter is best option, apart from particulate if application has moisture also then both coalescing and particulate filters are recommended. Please refer to the site below for suitable filters.

Web site: www.muc-products.de
E-Mail: info@muc-products.de
M&C Products Analysentechnik GmbH
Rehhecke 79 - 40885 Ratingen - Germany
Phone: +49 (0) 2102 935-0 Fax: +49 (0) 2102 935-111

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After replacing the battery on a 311TC analyzer we noticed that the indicator mark on the battery test is between 6 and 8 on the display. Charging it further does not increase the reading. Should the test for a fully charged battery be above 8 or is it enough for it to be between 6 and 8?

The normal indication of the charged battery would be between 6 and 8 so it is normal to read between those two marks when the battery is fully charged.

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We are using a 311 with A-2C cell due to CO2 in the gas being sampled. When the analyzer is not in use, can we purge it with nitrogen?

We do not recommend that you purge with N2. The A-2C sensor can be degraded by switching between CO2 and N2 backgrounds. Your analyzer has quick disconnect fittings, so it is best to use CO2 gas or otherwise just disconnect tubing to and from the unit after sampling the CO2 gas.

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Can the analyzer be calibrated on air?

he 311 series allows for an air calibration, although you can expect recovery time after saturating the sensor with high O2 levels if the analysis range is in low ppm. It is recommended to use a gas containing O2 of about 80% of the planned analysis range.

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