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Technical Support FAQ

CEA-9001 Flue Gas Analyzer
PEM-9002 Portable Emissions Monitor


How is NOx calculated in the PEM-9002?
What gases should I use to periodically check the accuracy of these instruments?
The display reads "NO sensor, valve overflow". What does this error message -- and others -- mean?
I'm having trouble with SO2 measurement using the PEM-9002 monitor. What should I do?
On the PEM-9002, why does the output of the charger read 15 VDC?
When charging the PEM-9002 we observe that the charger is hot. Is this normal?
We use the PEM-9002 for about 15 minutes, and suddenly the display indicates "SHUT OFF IN 30 SECONDS" and counts until it reaches 0 seconds and shut off. We turn it on again and after 15 minutes it happens again. I try to put a value of 0 in the Auto Off parameter but nothing happens.
Can I span calibrate the PEM-9002 in the field?
Please explain the meaning of No. 2, No. 4, and No. 6 fuel oil.
Why is storing the PEM-9002 only recommended if the battery is fully charged? Can I leave the instrument connected to the charger for an extended time?
For the PEM-9002, if one is using coal as a fuel, what are the typical values for CO2 Max?
For the PEM-9002, I get the message SYSTEM ERROR on the display. What causes this and what should I do to recover?
Can you provide more detail regarding the "R" command for the RS-232 data link?
Does the analyzer have to be in the "ON" position while charging the batteries?
What is the procedure for replacing the sensor on the PEM 9002?
How do you calibrate the Oxygen sensor in a PEM-9002 Analyzer?


How is NOx calculated in the PEM-9002?

The formula for the calculation of NOx in both Teledyne models CEA-9001 and PEM-9002 is the same:

NOx = 1,03 * NO.

This is an empirical ascertains formula fixed in the German general regulation called BImSchV. (There is a fixed percentage of 3% as a sum of NO2, NO3).

For conventional burners and heat systems, the measurement is relatively accurate. That means it is dependent on the measured concentration of NO.

The specified accuracy of the NO measurement: +/- 5 ppm (in measurement range 0 - 150 ppm) respectively +/-5 % of reading (up to 2000 ppm).

For all other special engines -- power plants or (diesel) motors -- it is not the optimal formula, because the percentage of NO2, NO3 can be higher than the maximum 3%. For these systems use another gas analyzer system (Infrared, etc.)

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What gases should I use to periodically check the accuracy of these instruments?

The gases needed are as follows:
They must be traceable mixtures and should be introduced into the unit under controlled conditions.

Frequency should be once a month initially and then less frequently depending on the amount of use, how well the instrument is treated, and how particulate laden and corrosive the sample stream is.

1. Cylinder (CO without H2 in N2):
CO = 400 ppm
Accuracy: +/- 2 % RDG

2. Cylinder (CO mixed with H2and O2 in N2):
CO = 1.000 ppm & H2 = 800ppm & 5,0 % volume
Accuracy: +/- 2 % RDG

3. Cylinder (NO in N2):
NO = 200ppm
Accuracy: +/- 2 % RDG

4. Cylinder (SO2 in N2):
SO2 = 300 ppm
Accuracy: +/- 2 % RDG

5. Cylinder (O2 in N2):
O2= 7,50 %volume
Accuracy: +/- 1 % RDG

6. Cylinder (CO in N2):
CO = 7.000 ppm
Accuracy: +/- 2 % RDG

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The display reads "NO sensor, valve overflow". What does this error message -- and others -- mean?

Low Batt: The battery is (almost) discharged. Action: The battery must be charged (some measurements are possible).

Batt Empty The battery is already discharged or empty. Action: The battery must be charged (No measurements possible).

T-Room Sensor: The temperature sensor for ambient (or room) temperature measurement is not connected or there is an interrupt in the wire. Action: The ambient temperature sensor must be connected or the thermo-wire (cable) must be replaced or repaired.

T-Gas Sensor: The temperature sensor for flue gas (or waste) temperature measurement is not connected or there is an interrupt in the wire. Action: The flue gas temperature sensor must be connected or the thermo-wire (cable) must be replaced or repaired.

O2 Sensor Defect: The oxygen sensor is faulty or not ready for measurement. Action: The instrument must be recalibrated by fresh air again. If the "O2 sensor defect" message stays on the instrument display after the third re-calibration, the sensor is probably in a "latch-up" status.

O2 Sens. Service: The oxygen sensor is used up and no longer suitable for measurement. Action: The O2 sensor must be replaced.

CO-Sensor: The carbon monoxide (CO) sensor is not ready for measurement (example: signal offset value in ambient air is too high) Action: The instrument must be recalibrated in ambient air.

CO-Sensor defect: The carbon monoxide (CO) sensor is faulty or used up. Action: The CO sensor must be replaced.

CO-val. Overflow: The carbon monoxide (CO) sensor signal value exceeds the nominal measurement range.

NO-Sensor: The nitrogen monoxide (NO) sensor is not ready for measurement (example: signal offset value in ambient air is too high or the lithium cell on the sensor PCB is discharged). Action: The instrument must be recalibrated by fresh air again or the lithium cell must be replaced.

NO-Sensor Defect: The nitrogen monoxide (NO) sensor is faulty or used. Action: The NO sensor must be replaced.

NO-val. Overflow: The nitrogen monoxide (NO) sensor signal value exceeds the nominal measurement range.

There are many reasons for this error message:
  • A dicharged lithium cell on the NO electronics board (PCB), if the instrument is more than 30 months old


  • Failure of the NO sensor (leakage, poisoning, loose contact between the PCB and the cell)


  • Loose contact between the sensor connector and the main PC


  • Too high or temporary offset value in ambient air
The problem may result from the discharged lithium battery on the NO sensor PCB. Normally this small cell should be replaced every 2 years. Please check the age of the unit. Our experience regarding the operating life of the NO cell is very good, with some cells working more than 5 years.

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I'm having trouble with SO2 measurement using the PEM-9002 monitor. What should I do?

There are 3 filters in the unit. The middle one interfers strongly with SO2 measurement.

1) Try removing the middle filter in the top lid assembly and placing a piece of tubing in its place. This filter can absorb SO2, degrading the reading accuracy.

2) When was the last time the unit was calibrated? We recommend calibration once per year.

3) How much is the difference between what you read and what you expect? How long did you wait before you took a reading? The unit is only as accurate as its specifications, and the unit will take some time to respond fully to a change in SO2 reading. Make sure you allow sufficient time for the reading to stabilize.

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I'm having trouble with SO2 measurement using the PEM-9002 monitor. What should I do?

It is normal to measure 15 VDC, if you use a digital-volt-meter and measure the voltage without burden (not in the electronic circuit during the charging mode). If you measure directly in the charging mode then you would measure 6,5 VDC till 8,5 VDC (depending of the charging status).

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When charging the PEM-9002 we observe that the charger is hot. Is this normal?

During the charging procedure, the charger unit could be hot because it is a power component. But more than 45C (for short time more than 50C) on the charger body (surface) is too much. Each charger has an internal thermal fuse which will act If it reaches/exceeds an internal temperature of 130C. It is a security feature of this electrical system. The observed warm temperature is likely a subjective assessment and not a measured result.

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We use the PEM-9002 for about 15 minutes, and suddenly the display indicates "SHUT OFF IN 30 SECONDS" and counts until it reaches 0 seconds and shut off. We turn it on again and after 15 minutes it happens again. I try to put a value of 0 in the Auto Off parameter but nothing happens.

The effect of the "15 minutes switch off function" caused from the configuration mode (look at the start side -> "Config. < S2 >"). It sounds as though you have it configured to "15 minutes" - switch off time, after 14 minutes and 30 minutes, the unit goes automatically in the switch off mode (30 seconds time) and than it switches automatically off.

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Can I span calibrate the PEM-9002 in the field?

You cannot span calibrate the unit in the field. The sensors will zero on ambient air when the unit is powered up.

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Please explain the meaning of No. 2, No. 4, and No. 6 fuel oil.

Numbers 2, 4 and 6 are commercially available grades of Fuel Oil.

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Why is storing the PEM-9002 only recommended if the battery is fully charged? Can I leave the instrument connected to the charger for an extended time?

The toxic gas sensors need to have a bias voltage on them for them to work properly. The bias voltage needs to be maintained on the sensors even when the unit if turned off. The bias voltage comes from the battery voltage. And it is not recommended to leave the unit charging for an extended period.

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For the PEM-9002, if one is using coal as a fuel, what are the typical values for CO2 Max?

The typical values for Coal are: A2 = 0.60 B = 0.008 CO2max = 18.7 % (+/- 0.5 % in dependence of the coal sort).

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For the PEM-9002, I get the message SYSTEM ERROR on the display. What causes this and what should I do to recover?

The SYSTEM ERROR message will be displayed if you have switched the instrument off per the RESET key during an active measurement.

You can simulate it if in measurement mode you push the RESET switcher. After that you should switch the instrument on and you will see this message (SYSTEM ERROR). Now you have two possibilities to go forward:

1. Push the button START for continuation of the operating mode (without deleting the memory blocks).

2. Push the button E (or ENTER) and the memory blocks respective configurations will be deleted or reset. After that you can continue the unit operation.

The SYSTEM ERROR message will be also displayed after extreme influence from external sources, such as an extremely high voltage spike in the line voltage or after a fuse replacement. In this case, push the button ENTER (E), after that the instrument should work well.

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Can you provide more detail regarding the "R" command for the RS-232 data link?

After sending the "R" command, the data can be received as "floating decimal value" (single type). This is like a "real" value. Some software developers use Turbo Pascal, Delphi, C++, and so on. The term name "floating value " or "real value" comes from the used development program.

An alternative to this is to receive the measured data from the memory blocks by using the "D" command. This data can be received in the "word" format.

Because of the very special data format of the RS232 interface, it is not easy to realize a communication for all software specialists.

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Can you provide more detail regarding the "R" command for the RS-232 data link?

After sending the "R" command, the data can be received as "floating decimal value" (single type). This is like a "real" value. Some software developers use Turbo Pascal, Delphi, C++, and so on. The term name "floating value " or "real value" comes from the used development program.

An alternative to this is to receive the measured data from the memory blocks by using the "D" command. This data can be received in the "word" format.

Because of the very special data format of the RS232 interface, it is not easy to realize a communication for all software specialists.

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Does the analyzer have to be in the "ON" position while charging the batteries?

The analyzer has to be in the "ON" position to start charging or while charging the battery.

After connecting to the charger, you must switch the instrument on, and then you can switch the instrument off again. If the instrument is already on, then you can connect the charger and switch the unit off.

In the on position, the analyzer will recognize automatically that the charger is connected and go in the charge mode. When there is more than 60% of the battery capacity, the charging procedure or function will be stopped and the instrument switches off.

But if the charger is left connected, the battery will be provided with a low current ("maintenance charge mode"). The value of the current depends on the condition of the battery cells (internal dynamical cell resistor).

The "battery charge manager" (including software, hardware and sensors like NTC and Shunt resistor) is a rather complicated instrument function. The manager has to measure and control the battery temperature, loading time, charge/discharge current, battery voltage and calculate the battery capacity. There are also several criteria to stop or finish the charge mode. Generally these batteries can be used for more than fives years in the instrument.

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What is the procedure for replacing the sensor on the PEM 9002?

Please refer to the following document:

PEM_sensor_replacement.doc

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How do you calibrate the Oxygen sensor in a PEM-9002 Analyzer?

Please refer to the following document:

PEM9002 Oxygen Sensor Cal Procedure.docx

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