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Technical Support FAQ

3350 - Control Room Oxygen Monitor for personnel safety

Our Model 3350 just started giving us problems. We put in a new B-3 sensor but after powerup the LED stays on continuously, the alarm light comes on, the horn sounds, and there are NO numbers in the display. Powering off/on does not help. We tried another new sensor, but got the same results. The Span and Arrow keys, when pressed, make no difference. Seems like if the sensor was the problem that the display would still show some numbers. This unit is in a welding shop, but it's not exposed to high heat or weather. Thoughts?
What are the ideal air flow conditions for this instrument?
Is there a Preventive Maintenance Procedure for this device?
Can I use the remote probe from a Model 335 in place of the one provided with my 3350?
How do atmospheric conditions impact O2 sensor readings?
Can the remote O2 sensor be used in a dusty environment without issue? We have a room which has a low level of dusty particles in which we would like to mount the remote O2 sensor. Are there any issues with doing this that may affect the sensors performance?
Our 3350 displays inaccurate readings and seems to drift too much. Any ideas?
What is the current rating on the relay contacts on the model 3350?
I have a question concerning the 3350, Oxygen monitor. We have a battery test button and I want to know what is the indication(s) you will see (display/Led) when the button is pressed, thanks.


Our Model 3350 just started giving us problems...

The problem you describe requires a little troubleshooting to determine the cause.

Please check the power supply voltage to the control unit with AC power connected, and then with back-up battery only.

Connect a volt meter across the + & - terminals on the back of the control unit and read the DC voltage:
1) With AC power cord connected, check for 15 volts DC
2) Disconnect the AC power cord, and check for 12 volts DC
3) Verify that all three fuses are OK.

Those steps will verify that the battery charger/power supply circuit is OK, and the problem is therefore inside the control unit.

Please advise if you want to send it back for repair, or continue troubleshooting to see which PC board needs to be replaced inside the control unit.

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What are the ideal air flow conditions for this instrument?

Regarding the Models 335 and 3350, which are oxygen analyzers for monitoring O2 deficiency (to support human respiration), Teledyne does not offer the advice you are seeking. I would suggest you contact the Safety Officer for your company to determine air flow requirements with regards to the product's ability to warn people of an O2 deficient condition in the room you are monitoring.

The sensor itself is not flow sensitive and is typically mounted in open air, which can be either flowing or still depending on the installation.

But Teledyne does not offer advice relative to where the sensor should be placed in relationship to the people or how often the air should turn over in the environment to ensure a safe work environment.

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Is there a Preventive Maintenance Procedure for this device?

This analyzer does not require much maintenance.

The maintenance procedure as mentioned in the operating manual is sufficient like fuse replacement, Micro Fuel cell replacement/installation and ordering/handling of spare cell.

Please just follow the manual for these. Apart from the above we can add some of the points during maintenance like:
  • Before replacing the new cell into analyzer, always clean the cell adapter metallic contact with isopropyl alcohol and then replace the new cell in the analyzer. The reason is if due to some reason the cell is physically damaged then the electrolyte will be spread on this metallic contacts & will not make good contacts between cell & cell adapter metallic contacts.
  • Perform the calibration on weekly basis as recommended by manual.
  • If you are making any flow through type arrangement for calibration then ensure that vent line is free flowing and not creating any back pressure on cell. If it is supplied with analyzer then kindly regret this point.
  • If you are performing span calibration on ambient air then ensure that O2 concentration as recommended 20.9%, if not then use good Inst. Air for calibration.
Follow the manual for the safety checklist & battery back system operation if installed any.

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Can I use the remote probe from a Model 335 in place of the one provided with my 3350?

No, since the 3350 uses a different probe assembly this is not possible. The 3350 requires the thermistor to be wired back to the electronics portion. Cable Color code is Red (Sensor +), Black (Sensor -), White (Thermistor), Green (Thermistor), and Green/White (Shield).

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How do atmospheric conditions impact O2 sensor readings?

Please refer to the following document:

impact_of_atmospheric_conditions_on_O2_readings.pdf

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Can the remote O2 sensor be used in a dusty environment without issue? We have a room which has a low level of dusty particles in which we would like to mount the remote O2 sensor. Are there any issues with doing this that may affect the sensors performance?

Over time the dust may prevent the flow of O2 to the sensor from ambient and cause a false low reading. That is possible.

We have tested this but this is based on our understanding of the principle of operation of the sensor. However if the sensor is mounted so the sensing surface faces down then the dust would tend to settle on the part of the sensor that is not bothered by it.

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Our 3350 displays inaccurate readings and seems to drift too much. Any ideas?

Make sure that the sensor is not too old. The unit may simply require sensor replacement. Another thing to check is to make sure that the flow through adapter is not attached to the sensor when the sensor is meant to sample ambient air. If the adapter is installed on the sensor probe there will not be enough air flow across the sensor to insure proper readings.

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What is the current rating on the relay contacts on the model 3350?

The three alarm-circuit connectors are screw terminals for making connections to internal alarm relay contacts. There is one set of contacts for each of 3 different types of alarm.

Alarm 1 (CAUTION), Alarm 2 (DANGER), and Cell Fail. Contacts are Form C, with normally open and normally closed contact connections capable of switching up to 3 ampere at 130 VAC into a resistive load (3A for 30VDC) maximum.

The alarm relay circuits are designed for failsafe operation, meaning the relays are energized during normal operation. If power fails the relays de-energize (alarms activated). Alarms are also available factory configured for non-failsafe operation which would extend the life of the battery standby power if applicable.

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I have a question concerning the 3350, Oxygen monitor. We have a battery test button and I want to know what is the indication(s) you will see (display/Led) when the button is pressed, thanks.

Yes , when the “BATTERY TEST” button is pressed, the LED will not turn on.
During normal operation the LED will remain off and will illuminate only when there is a Low Battery condition.

Refer to chapter 3.5 of the instruction manual for additional Battery Test information.

Periodically test the condition of the battery pack by pressing the “BATTERY TEST” pushbutton inside the instrument’s control panel and note the battery condition by viewing the "battery low" LED on the front panel. Release the pushbutton to return to the normal sampling mode. The battery test provides only an indication of the battery state under the test conditions; it is possible that a battery might test well but perform for only a short time under actual operational conditions (a characteristic of the battery, not the analyzer), so it is very important that power outages be corrected without delay. Furthermore, TAI recommends that the instrument be tested periodically by operating it for several hours without AC power (that is, under battery power). Top of page



   

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