Explanation of the specification items -Short-term measurement detector tubes-

External appearance

The external appearance of the detector tube(s) is briefly illustrated.

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.

Correction factor

When measuring an extended range of concentration, that is, when the measurement is performed with other than the standard number of pump strokes, the tube reading should be corrected by multiplying the reading by the prescribed correction factor.

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 colour change at the entrance of the detecting layer. This value is followed by the parenthesized number of pump strokes required for seeing this concentration.

Colour change

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

Corrections for temperature & humidity

For detector tubes whose indications are affected ±10 % or more by the fluctuation of temperature or humidity, the tube readings should be corrected.
Whether or not such corrections are necessary are indicated here.
The correction data, if necessary, is provided in the instruction sheets provided with the detector tubes.

Relative standard deviation

An indicator of the accuracy of the detector tube. It represents how the tube indications may deviate from their mean value in percentage:
Relative standard deviation= Standard deviation (σ)Mean value () x 100 (%)

Shelf life

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

Reaction principle

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

Possible coexisting substances and their interferences

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 colour to be pale. For your reference, the column "Changes colour by itself to" is given to show how the interferences will change the colour of the detecting layer if they exist without the presence of the target gas. "No" represents that no colour 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 vapours 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 us or our distributors in your territory.

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 figure which is multiplied by the concentration interpreted form the colour starting on the detector tube. 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 GASTEC distributor.

Calibration gas generation

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