How to read a Handbook Page


Every Nextteq Detector Tube has it own unique handbook page that contains a wealth of information.  The top section identifies:

  • Name and chemical formula of the gas to be detected
  • Tube no.
  • Photo of the tube and a tube illustration
  • Other substance (s) measurable with this detector tube (Correction Factor / Scale)


Detector tubes are primarily designed to measure specific gases. But it is also possible to measure other substances of similar chemical properties with the aid of a correction factor or a correction scale. A correction factor is a value which is multiplied by the concentration read directly off the detector tube concentration scale. The correction may also be presented as a correction scale if the correction relationship is nonlinear. Please make use of the correction factor/ scale measuring range as a reference. Moreover, this factor may vary slightly between production batches. For a more precise factor please contact your Nextteq® distributor.


  • 1. PERFORMANCE

    Measuring range

    The range of the substance concentrations that can be measured with the detector tube. The standard measuring range, or range of the printed calibration scale is given in the shaded box. Some lower limit values of the standard measuring ranges are parenthesized when they are not printed on the tubes but only their scale lines are printed.


    Number of pump strokes

    The number of pump strokes required for measuring a given range of concentrations. The volume to be sampled with those strokes is given in the parentheses. The standard pump strokes and the standard sampling volume are given in the shaded box.


    Sampling time

    The total waiting time to read the detector tube. (=A waiting time for 100 mL (or 50 mL ) x n. ( Number of pump strokes) )


    Detecting limit

    The lower limit of the substance concentration that the detector tube can detect. This minimal concentration can be recognized by a slight color change at the entrance of the detecting layer. This value is followed by the parenthesized number of pump strokes required for seeing this concentration.


    Shelf life

    The period that Nextteq International will warrant the quality of the detector tubes, provided that they are stored under the prescribed conditions.


    Operating temperature 

    Operating temperature is the range of temperatures at which the detector tube will function properly.


    Reading 

    This is reading method used for the detector tube. i.e., direct read for the application, direct read for a different application, direct read using a conversion chart or table, concentration chart, color chart, or color intensity.


    Color Change

    Indicates how the detecting layer of the detector tube will change its color by the reaction with the target substance. This is shown in the form of:


    Original color → Changed color


  • 2. RELATIVE STANDARD DEVIATION

    The method of generating the calibration gas that is used for calibrating the detector tube or testing its accuracy.


  • 3. CHEMICAL REACTION

    The chemical reaction of the target substance with the reagent(s) in the detector tube is briefly stated.

  • 4. CALIBRATION OF THE TUBE

    The method of generating the calibration gas that is used for calibrating the detector tube or testing its accuracy.


  • 5. INTERFERENCE AND CROSS SENSITIVITY

    Substances that are liable to coexist with the target substance and their influences on the tube indications are listed here. The column "Concentration" lists the lowest concentration that may affect the indication ±10 % or more, or the highest concentration that is assured of no influence to such extent.


    These concentration levels are expressed either as quantitative ratios of interferences to the target substance (e.g., ≥1/5, ≥2 times) or concentrations of interferences themselves (e.g., ≥3%, ≤500 ppm). Where, ≥ reads" equal to or higher than" and ≤ reads "equal to or lower than" .The presumed influence by coexistence is given in the column "Interference" where the " + " sign suggests 10% or higher indication, the " - " sign expresses - 10% or lower indication, or "No" means no influence. "Bleaching" means that this interference will cause the reaction color to be pale. For your reference, the column "Changes color by itself to" is given to show how the interferences will change the color of the detecting layer if they exist without the presence of the target gas. "No" represents that no color change will be observed. The table of this interference gases primarily expresses the interference of each coexisting gas in the gas concentration range, equivalent to the gas concentration by some of the other coexisting gases or vapors mentioned from the main purposes of using this detector tube. Therefore, the test result may be given positive result by the other substance not listed in the table. If more precise information is needed, please contact your Nextteq® distributor.