​​402REU FAQ​

What is the highest possible range that the 402REU can be configured and maintain the linearity of the measurement?

What is the difference between a 402R configured for 100% H2 fuel and one configured for a 40/60 mixture?

How can I troubleshooting electronic problems with the 402, 402R, and 402REU?

What is the start-up procedure for Models 402, 402R, and 402REU?

What is the procedure for flame guard circuit calibration?

Why is the output signal of the 402REU defined as the concentration of ethylene glycol (C2H6O2)?

The sample gas contains CO and CO2 as well. Why does the CO and CO2 not interfere with the detection of C2H6O2?

I would like to calibrate a model 402REU with 300ppm benzene. What is the procedure to get the 402R operating correctly with different span gases? (Non-methane)

Do you have a conversion table for different gas calibration for the 402REU?

What is the H2 flow to 402R provided for THC in CO2 (Premier Guard)?

For 402R analyzers set up for 100% H2 fuel for THC in N2 or argon, what would fuel flow be?

For 402R analyzers using 40/60 nitro fuel (40% H2), what is the fuel flow?

What is required to change a 402 designed for 40/60 fuel over to 100% H2?

The flame ignition has failed on our 402REU. The air, zero gas, span gas, and fuel show no problems. Any advice?

How can I reconfigure a unit which is working on an O2 background, with 60 40 fuel mix to work on H2 background, with the same fuel?

What is the maximum pressure that can be applied to the unit ?

Regarding to 402REU spare parts, there are three restrictors in the flame ionization cell. Their part No.s and descriptions are:

R00596 restrictor #600,
R00597 restrictor #200,
R00598 restrictor 30SCC/MIN N2 6PSIG.
So, what is the exact meaning of #600 and #200?

Is there a way to convert the 220 VAC operating voltage to 110 VAC on the 402REU?

What are the air and fuel consumption rates on the 402REU?

Can we add alarms to our 402REU?

I have an instrument using 40% H2/60% N2 fuel, but I would like to substitute 40/60% of H2/HE. What modifications to the unit are required?

Can I just replace the thermistor in this unit?

How long is the average life span of a Flame Ionization cell?

When I change the fuel gas on the unit, the readings change dramatically and take time to come back up. Why is this?

If I change the background gas of the unit from Argon to N2 or CO2 or vice versa, do I need to optimize the pressure setttings of the unit for maximum signal?

What is the effect on sample pressure changes to the unit?

We have a facility with a 402REU in 220 Volt configuration and they have been running it successfully there. However they are concerned from a safety standpoint that the power entry module is universal and that it is possible for some to hook up a 110 cord and thus connect the unit to 110 power. They have asked if it is possible for the unit to be reworked in the field to convert from 220 to 110 configuration. Is this possible?

What is the procedure to replace a gas regulator in the Model 402R analyzers?

For additional questions, please contact Technical Support​​.


Q: ​What is the highest possible range that the 402REU can be configured and maintain the linearity of the measurement? ​

A: 0-6% Full scale ​

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Q: ​What is the difference between a 402R configured for 100% H2 fuel and one configured for a 40/60 mixture? 

A: A 402R analyzer is not designed to switch between two different types of fuel without modification to the sample system.

The sample system is either built for the standard 40/60 mix fuel, or for 100% H2 fuel. The fuel type is specified at the time of purchase. 

A sample system built for 100% H2 fuel is built with a lower flow restrictor in the fuel gas line. This limits the flow of 100% H2 to 30 scc/m instead of the standard 200 scc/m. ​

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Q: ​How can I troubleshooting electronic problems with the 402, 402R, and 402REU? 

A: Troubleshooting electronic probles for this series can be found by downloading this PDF file. ​

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Q: ​What is the start-up procedure for Models 402, 402R, and 402REU? 

A: Start-up information for this series can be found by downloading this PDF file. ​

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Q: ​What is the procedure for flame guard circuit calibration? 

A: Adjusting P1:

This procedure is done at the factory, but may need to be re-done after replacing the restrictors, and after re-calibration. This procedure applies for both types of fuel.

Set the flame guard circuit after calibration has been completed.

Trim-pot P1 is located on the back of the flame-guard / anode power supply, PC board assembly. It is used to adjust the sensitivity of the flame guard circuit. When properly adjusted, the flame-out light should come on within 10 to 20 seconds after a flame out.

1) Turn the pot clockwise about 75% of its turns. Then ignite.

2) Turn the pot counter-clockwise until the flameout light just comes on.

3) Turn the pot gradually clockwise again (while repeating the ignition procedure) until the light remains off.

4) Check the flame guard circuit calibration by closing off the fuel at the tank, and observe that the light comes on when the fuel pressure drops.

Note: This procedure for the set-up of the potentiometer P1 can also be found in the Flame Guard Circuit Calibration section of the instruction manual.​

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Q: ​Why is the output signal of the 402REU defined as the concentration of ethylene glycol (C2H6O2)? 

A: C2H6O2 is a hydrocarbon and as such ionizes in the flame to C+ ions which the FID is sensitive to.

You can calibrate the FID with a known concentration of C2H6O2 and report the output as ethylene glycol equivalents so that all HCs present read as ppm C2H6O2.

Note: Vapor pressure above indicates that only about 53 ppm C26O2 (at 20 Deg C) can be in vapor state at 1 Bar A pressure.

Ths means a cal tank of about 200 PSIG (13 Bar A) of only 3.97 ppm C2H602 in N2 can be made up by a gas cal supplier because of the condensing nature of ethylene glycol at high pressures. The volume in the cal tank is only about 400 liters, so it won't last too long at 30 to 1000 ccm flow into the instrument. ​

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Q: ​The sample gas contains CO and CO2 as well. Why does the CO and CO2 not interfere with the detection of C2H6O2? 

A: CO and CO2 do not ionize in the flame of H2 and air and N2. CO forms CO2 by oxidation and does not ionize. CO2 also does not ionize.

Only HCs ionize (form c+ ions) which the FID is sensitive to.​

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Q: ​I would like to calibrate a model 402REU with 300ppm benzene. What is the procedure to get the 402R operating correctly with different span gases? (Non-methane)

Do you have a conversion table for different gas calibration for the 402REU?

A: For the best accuracy, you should span with the same type of gas that you wish to measure. Meaning if you want to measure benzene, you should span with benzene.

In a theoretical sense, the FID is a carbon counter and counts the number of carbon molecules. However, we have done testing with a variety of gases and found that the theory does not really match the reality. Therefore we do not recommend the use of conversion factors when calibrating with one type of hydrocarbon and measuring another.

It is best to calibrate with one type of hydrocarbon, and measure the same type. If this is not possible, you should report the results in "span gas equivalent terms", i.e. if you span in methane, you report a total hydrocarbons in methane equivalent, and it you span in benzene, you report the results in benzene equivalent.​

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Q: ​What is the H2 flow to 402R provided for THC in CO2 (Premier Guard)? 

A: When pure H2 is used, it is: 30 ccm with 100% H2 fuel, CO2 sample flow is 30 ccm, Air support flow is 600 ccm. ​

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Q: ​For 402R analyzers set up for 100% H2 fuel for THC in N2 or argon, what would fuel flow be? 

A: 30 ccm 100% H2. ​

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Q: ​For 402R analyzers using 40/60 nitro fuel (40% H2), what is the fuel flow? 

A: 200 ccm with 40/60 ratio H2/N2; if a blend was used; 30 ccm CO2; 600 ccm Air. ​

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Q: ​What is required to change a 402 designed for 40/60 fuel over to 100% H2? 

A: A fuel restrictor is changed and pressure regulation is changed.


fpr = forward pressure regulator
bpr = back pressure regulator through as bypass 

PSIG Range

Gas

Flow cc​m

TAI Restrictor

Background gas condition

fpr 7-10 on R2

40/60 H2/N2

200

R597

402R on O2, N2, Ar, CO2

fpr 6-10 on R1

Sample

30

R598

Relocate fuel solenoid valve to sample line after V1 (see piping diagram)

fpr 15 on R3

Air

600

R596

100%H2 as fuel

fpr 2-4 on R2

100% H2

30

R598

402R on N2, Ar, CO2

(Note: O2 must be diluted 50/50 with about 8 psig regulated N2) (too much H2Ov formed)

fpr 8 psig R4

N2

30

 

 ​

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Q: ​The flame ignition has failed on our 402REU. The air, zero gas, span gas, and fuel show no problems. Any advice? 

A: Possible problems with the flame failure are: 

1- Ignite coil of the sensor is open.
2- Air and fuel support are not reaching the sensor. 
3- Thermistor is open. 
4- No AC voltage to the ignite coil. 

Please check as follows: 

Ignite coil open: 
Located the 4 pin connector on the left hand side of the sample module ( refer to drawing D-64783). The connector has 4 wires, 2 wires are 16 gauge = Red and Purple and 2 wires are 22 gauge white and white/green. Separate these 4 wires from the sample module to the main board by removing the plug from the connector. Check resistance of the ignite coil, Red and Purple wires; resistance must be less then 1 ohm. 

Thermistor open:
Same connector for ignite coil. Measure resistance of 2 wires: white and white/green. Resistance should be around 50 to 100K, depending on the oven temperature. If the coil or thermistor are open, please replace the FID sensor B13207. Do not re-connect the cable mentioned above until the end of the test. 

Air flow check: 
Using a displacement flow meter with the range of 600ccm to 1000ccm, connect at the sensor vent, turn off the fuel, and sample to the analyzer. Leave only air to the analyzer. Displacement flow meter must read around 300 to 600ccm. If it reads lower than 300ccm, the Air restrictor must be replaced. 

Fuel check: 
Turn off the air to the analyzer, turn on the fuel, position the range switch to ignite and hold. The flow meter must read between 150 to 200ccm (for fuel using 40%H2 and 60% Nitrogen mix). For the analyzer using pure Hydrogen, the flow meter must read 20 to 40 ccm. If the displacement flow meter cannot read this low, connect a piece of tubing in place of the flow meter, and place the end of the tubing 1" in to the water. This will produce 2 bubbles a second. If the fuel is not enough, the fuel restrictor needs to replaced.

No voltage to the ignite coil: 
Re-connect the 4 wires connector mentioned above, and connect a AC voltmeter across Red and Purple wire. Then position the range switch to ignite and hold. Voltmeter must read between 1.5 to 2.5VAC. If it does not read the correct voltage than the transformer or range switch is bad. ​

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Q: ​How can I reconfigure a unit which is working on an O2 background, with 60 40 fuel mix to work on H2 background, with the same fuel? 

A: Calibrate the analyzer with CH4 balance N2, keeping the Air, Fuel pressure the same, and just increase the sample pressure by a factor of 1.5. ​

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Q: ​What is the maximum pressure that can be applied to the unit ? 

A: 25 psig ​

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Q: ​Regarding to 402REU spare parts, there are three restrictors in the flame ionization cell. Their part No.s and descriptions are:

R00596 restrictor #600,
R00597 restrictor #200,
R00598 restrictor 30SCC/MIN N2 6PSIG.
So, what is the exact meaning of #600 and #200?

A: These numbers represents the gas flowrate of these restrictors in this analyzer.

#600 is same as 600CC.

600 Standard Cubic Centimeters per Minute (SCCM) or (scc/min) ​

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Q: Is there a way to convert the 220 VAC operating voltage to 110 VAC on the 402REU? 

A: To change the analyzer from 220VAC to 110VAC, refer to the drawing C​6779; under​ the note section 3, from 3.1 through 3.13 is the procedure. ​

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Q: ​What are the air and fuel consumption rates on the 402REU? 

A: Air - 600 sccm  (standard cubic centimeters per minute) 
Fuel - 200 sccm 
Sample - 30 sccm
(Fuel is changed to 30 sccm when using 100% H2) ​

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Q: ​Can we add alarms to our 402REU? 

A: The alarm PC board assembly (p/n A09309), can be installed in the 402REU.

It is also necessary to install the relays in the sockets on the mother board, and the potentiometers and dials on the front door. Then complete the wiring of the pots to the motherboard.

The relays are for switching states, and the pots and dials are for setting the desired set-point to trigger alarms.

For this modification, reference the alarm option package (p/n A64994). Here is the relevant schematic. ​

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Q: ​I have an instrument using 40% H2/60% N2 fuel, but I would like to substitute 40/60% of H2/HE. What modifications to the unit are required? 

A: No modifications are needed. You only need to recalibrate the unit. ​

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Q: ​Can I just replace the thermistor in this unit? 

A: No, you cannot just replace the thermistor, you must replace the whole cell-place assembly. which includes the 100k thermistor, ignitor coil, and the collector. These components are welded. The replacement sub-assembly is p/n B13207. ​

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Q: ​How long is the average life span of a Flame Ionization cell? 

A: This item can last the life of the instrument under ideal conditions. If the sample is very clean, and the sensor vent is not restricted such that condensation does not build-up in the FID chamber. There could be component failure, the coil can overheat. The collector walls can become contaminated, causing loss of sensitivity. In most cases I would say that the cell-plate assemblies usually last 5+ years. ​

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Q: ​When I change the fuel gas on the unit, the readings change dramatically and take time to come back up. Why is this? 

A: It is always necessary to Recalibrate / Re-standardize the analyzer when the fuel or air supply gases are changed. Refer to
the man​ual for specif​ics. 

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Q: ​if I change the background gas of the unit from Argon to N2 or CO2 or vice versa, do I need to optimize the pressure setttings of the unit for maximum signal? 

A: No. Only a re-calibration on a standard is required (standard cylinders of span and zero gases). ​

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Q: ​What is the effect on sample pressure changes to the unit? 

A: These have been supplied in two main versions -- a low pressure version in which the sample pressure applied to the unit must be over 5psi, and a normal unit in which the sample pressure applied ot the unit must be over 10psi. Internal at the detector, sample pressure must be controlled tightly due to the effect of flow and pressure changes on the output of the FID detector.


It is for this reason that TAI has supplied this unit with pressure regulators inside the unit for Air, Fuel and Sample. Small changes above the minimum pressure required for regulation have a negligible effect on the reading of the unit. If the pressure falls under the minimum required, readings can change quite a bit as the sample regulator in the unit will not have sufficient headroom to operate and therefore will not regulate properly.

Data was taken on quantity four units set up to measure THC in O2 and is shown in the table below :

Pressure to ​analyzer

Unit One Data
(ppm reading / sample pressure gauge reading)

Unit Two Data

Unit Three Data

Unit Four Data

30 psi

0.07 ppm / 4 psi

1.19 / 5.6 psi

1.02 / 4 psi

0.25 / 5 psi

28 psi

0.07 ppm / 4 psi

1.1 / 5.6 psi

1.02 / 4 psi

0.24 / 5 psi

25 psi

0.06 ppm / 4 psi

1.21 / 5.6 psi

1.01 / 4 psi

0.24 / 5 psi

20 psi

0.06 ppm / 4 psi

1.21 / 5.6 psi

1.01 / 4 psi

0.25 / 5 psi

15 psi

0.03 ppm / 3.8 psi

1.22 / 5.6 psi

1.01 / 4 psi

0.26 / 5 psi

12 psi

0.01 ppm / 3.5 psi

1.32 / 3.8 psi

.73 / 3 psi

0.28 / 5 psi

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Q: We have a facility with a 402REU in 220 Volt configuration and they have been running it successfully there. However they are concerned from a safety standpoint that the power entry module is universal and that it is possible for some to hook up a 110 cord and thus connect the unit to 110 power. They have asked if it is possible for the unit to be reworked in the field to convert from 220 to 110 configuration. Is this possible? 

A: Please refer to the following f​or instructions on converting the 402REU from 230 to 115VAC 402R.pdf

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Q: ​ What is the procedure to replace a gas regulator in the Model 402R analyzers? 

A: Please refer to the following for instructions: 402R_regulator_replacement.pdf. ​

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