Other common questions

To visitors who are considering our product

  • How frequently should I calibrate the O2 analyzer?

    It depends on the use and environment. Please inquire me individually.

  • Can we make measurements with O2 the entire O2 analyzer is placed in sealed space filled with sample gas?

    Zirconia oxygen concentration cell type O2 analyzer, like TB series, measures O2 concentration by translating cell EMF. Cell EMF is generated by difference of O2 partial pressure between reference gas and sample gas.
    Reference gas is air and its O2 concentration is calculated with 20.6%. If the entire sensor is placed in N2 gas or O2 gas, measurement can’t be done because of a lack of difference of O2 partial pressure.
    In case of this use, we recommend the zirconia limiting current type FG series.

  • Is a O2 analyzer usable for the furnace which is over specified temperature?

    It is often usable by choosing sampling position.
    Give us the information about and we will recommend the best way.

  • What is the merit/demerit of Zirconia oxygen analyzer in comparison with other methods of oxygen analyzer?


    In Comparison with other method of oxygen analyzer…
    ①Measurement under high temperature without cooling is possible.
    ②Long-lasting sensor
    ③Quick response


    In Comparison with other methods of oxygen analyzer…
    ①When a flammable material is included in sample gas, oxygen reacts with it in a sensor part and display of oxygen concentration may be displayed lower than acctual one.
    ②Warm-up time is necessary.

  • About product delivery time

    As for standard models we keep in stock in the state of semi-finished product.

    Therefore there are some models which can be shipped in a few days for manufacturing and inspecting in your emergent request. However it is necessary to adjust it with a process in the company and we usually have delivery date of around three weeks in for standard products.

    In addition, in the case of a non-standard product including the metal box, please think that it takes around 1.5 months after delivery specifications is returned.

  • About 2 year-warranty

    1.We will repair it gratis immediately after returning back to our factory toward our clear fault about material, loss of work and trouble that occurred in 2 years from our shipping or customer’s starting of use.*1,2,3,4
    2.We will charge when there is a dispatch request of our technical person even if during a term of a guarantee.
    3.We will correspond to requirements from your company or customers and repair of the product even after guaranteed period.
    The expense of this case will be decided after discussion each time.

    ※1. Consumable parts such as filters, O-rings are excluded.
    ※2. Corrosive gas such as strong acidity, strong alkalinity must not be included in sample gas.
    ※3. It is limited to our original products or products shipped by us.
    ※4.There is no replacement during the repair period regardless of the inside or outside the guaranteed period.
    Therefore we recommend customers to purchase a spare one when they consider it an important equipment.

  • About Base gas for oxygen analyzer

    This instrument is calibrated with standard gas of Oxygen/Nitrogen.
    Instructions error appears when used without re-calibration in the case of Oxygen/Argon, or Oxygen/Helium atmosphere. Carry out re-calibration with the standard gas which is same kind of gas as your atmosphere.

  • Is it possible to provide a Traceability certificate?

    Yes, it is possible. When a traceability certificate is necessary for new supplies or a periodic inspection, please contact us beforehand. When there is no prior contact, we may not be able to submit it depending on the standard gas, inspection equipment we used.
    Even that case, we can cope by re-examination if you can return it.

  • Is pure nitrogen or the high purity gas possible to be used as zero gas?

    No, it is not possible. Use Oxygen/Nitrogen standard gas whose concentration is known suitable for the range.

  • About unit of atm indication

    Indicaiton in unit atm is possible in Control unit C-48. It is measurable from minimum of 10-30atm. It is possible to display oxygen concentration of even very small amount under decompression and reduction atmosphere.

  • Is there any explosion-proof type in line-up?

    None of our products supports explosion-proof standard.

  • Is there any model which can be used under decompression atmosphere? What other particular inspection do you do?

    There are TB-ⅡV and TB-ⅡVN that are suitable for vacuum furnace, Glove box.
    They are measurable under decompression of 10-3Pa, and we have had approx. 20 years experiments. We have a new product, TB-IIVN sensor, which is improved reaction speed, in our line-up. Please refer to the page of TB-IIV and TB-IIVN for details.
    We do leak inspection for all of them with helium detector. We check that it does not detect with a range of 1*10-9 atm・ cc/sec.

  • About the influence of flammable gas

    Our analyzer uses ceramic heated at high temperature
    When flammable gas coexists(CO,H2, CmHn) in sample gas, , there is a reaction of [CO+1/2O2 → CO2, H2+1/2O2 → H2O]. Therefore a combustion reaction occurs in sensor, and instruction value may be displayed low.
    But it is possible to measure O2 partial pressure less than 1 X 10-20atm dissociated from gas in H2 (CO) atmosphere or [H2+ inert gas] atmosphere to use with a heat-treatment atmosphere and manage the atmosphere. [CO+1/2O2 ⇔ CO2 , H2+1/2O2 ⇔ H2O]

  • About influence of sample gas pressure

    This instrument measures an O2 partial pressure. The instructions value also changes according to the change of pressure with the gas of same Oxygen concentration, too.
    For example, when atmosphere air (20.60%) is decompressed to 0.5atm, the instructions value becomes 10.30%.

  • Is the measurement of gas including moisture possible?

    About 10% moisture (depending on the kind of fuel) is included in combustion exhaust gas. When this moisture condenses and touches the sensor as water, the high temperature heated ceramic sensor may be damaged by heat-shock. But there is no problem if it is measured as steam at high temperature. Our Oxygen sensor for exhaust gas can be installed to facilities directly and is designed to be able to sample directly.
    The dehumidifiers such as a drain pot, the electronic air conditioner are necessary when it is necessary to draw a sample.

  • Is the measurement of gas including dust possible?

    A. It depends on quantity and quality of dust in the actual atmosphere, we cope with the measurement in an atmosphere with the dust as follows. (TB series)
    1. For sensor cell protection, the device reduces the dust which comes in contact directly by installation of TB filter.
    2. You can use a manual/automatic purge system by accessory attachment.
    We will suggest accessories for pre-processing to your atmospheres.

  • Is the management of atmosphere on combustion conditions less than M-value 1 possible?

    (CO+H2)% at less than 10-20atm can be measured by measuring dissociated pO2 from [CO+H2/CO2+H2O] equilibrium condition.
    Our C-28C can display at the range of -O2%→0→+O2%. (m-value 1 is equal to 0%of C-28C)
    1%(CO+H2)+1/2%O2⇔1%(CO2+H2O), so 1%(CO+H2) corresponds to –1/2%O2.

  • What is the cautions when installing the sensor?

    Please be careful about the followings.
    1. In the sensor part, zirconia ceramic is heated to 735 degrees Celsius.
    When water comes in contact with the sensor, a cell might be damaged by heat-shock.
    When the temperature of sample gas is high, use accessories as drain pot or mist separator etc. so as not to let water from condensation enter the sensor part.
    When installing adjust the sensor direction and tube direction so that water doesn’t enter the sensor part.
    2. This equipment measures partial pressure of oxygen. Do not supply back pressure to sensor. Install it so that pressure caused by blockage of flow after sensor and tubing doesn’t occur.
    3. Be careful not to burn yourself and melt parts as the sensor part is very hot.


To customers who already use our product

  • After vacuum piping and return the pressure with inactive gas, O2-concentration becomes higher than it is. Why?

    For example, if the atmosphere is reduced the pressure of 1Pa,
    the oxygen partial pressure is ≒ 0.2×105atmO2=2ppm.
    And the reduced atmosphere return the pressure of atmospehere,
    O2-concentraion became 206000 ppm.
    Once O2-concetraion became lower, compressed with N2, Ar etc,
    and the atmosphere surrounding a sensor assembly which was decompressing
    is compressed.
    Depending on locations between a sensor assembly and INLET,
    O2-concetration may go up to near 10%.
    After that, the compressed atmosphere which was surrounding a sensor assembly
    diffuses and O2-concetration go down to the value of the inactive gas.
    The rise of O2-concetration is not trouble, which indicates the value of
    the time and the spot.

  • When I measured the exhaust gas, O2 analyzer of Daiichinekken indicates lower value than another portable analyzer. Why?

    Almost all of Our company’s O2 analyzers measures gas which contains moisture by direct detection. Therefore, measured gas is diluted by moisture and O2-concetration goes down by 10 % of the value that is detected by other types. In extreme example, if 50% of moisture is in a sample gas, the difference of the indication will be half of the dry based indication.
    We have the model which is used as a moisture meter by measuring O2 of a wet base and a dry base.

  • The indication of O2 analyzer never change even if air or sampling gas is introduced.

    First, Check the lower indication of C-28C.
    When the menu key is pressed, the temperature 735℃ is displayed. Then press the menu key once again.
    At this state, the lower indication of C-28C shows cell electromotive force
    (cell EMF).
    ①Introduce air again and check EMF.
    ②Next, introduce calibration gas (or sampling gas).
    ③Compare the EMF differential between air and gas with the value in the graph in the manual, if the actual EMF differential is extremely low, the cell may have deteriorated.
    ④If the actual EMF is appropritate, calibration may have failed.
    It is considered that the gas of the different value was introduced, and
    you had calibrated either Zero or Span.
    Please CAL CLEAR and calibrate again.

  • O2 concentration is different from the expected value. Why?

    There are cases that O2 analyzer indicates both higher and lower,
    but please introduce zero calibration gas and span calibration gas, then check
    their indications. If their indications are not appropriate, please calibrate.
    When the indication of sampling gas is still different,
    ①In case of higher indication
    Sampling source is at negative pressure, so air comes in from somewhere.
    Please tighten joints, change O-rings to new one, Check the cracks around
    the sensor and piping.
     In the case of the O2 analyzer for exhaust gas, the indication may also be
    higher because of runnig back of the aspirator air which is caused by blockage
    inside and at the outlet.
    ②In case of lower indication
    Please consider whether sampling gas contains combustible gas or not or its
    possibility. Generally, if CO or H2 is contained, O2 equivalent to half amount of
    them is consumed by combustion.
    *Even if the indication value on oxygen analyzer deffers from expected value,
    measurement are often correct.

  • How far can a signal cable be extended?

    A signal cable can be extended up to 100 meter.
    But the appointed date of delivery may be postponed depending on the stock.

  • When air is introduced, the indication is shifted widely. Why?

    It is no problem when a zirconia oxygen concentration cell is used for low-concentration O2 gas.
    When the O2 concentration becomes 1/10, the EMF of zirconia cell in 735℃ increases by 50mV.
    For example, 50mV is increased by the change of 100% to 10%, 10% to 1% … by 1ppm to 0.1ppm.
    When air is introduced, changing of 1mV makes error of 1%, but it is almost accurate when a little percent of O2 gas is measured.
    On the other hand, measuring high-concentration O2 gas is influenced widely.
    In these cases, we recommend the zirconia limiting current type (FG series) rather than zirconia oxygen concentration cell type in case of it.

  • In case of a failure, What happens to the indication?

    As causes of a sensor failure, there are cell deterioration, HEATER broken, RTD broken and so on. Almost all failures makes indications to rise.
    When an analyzer is used for controlling low-concentration O2 gas, this function
    works for safer direction.

  • Are sensors compatible among same models?

    Yes. But each sensor has individual differences, so we calibrate to match a sensor and a control unit before delivery. Therefore, Calibration is needed if sensor assemblies are exchanged between sensors because approx.±10% error of indication may occur by sensors’ individual differences. This is the same if a sensor assembly is exchanged to replacement parts.