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    Home > Chemicals Industry > Chemical Technology > Determination of trace moisture in industrial fluoroalkanes (4)

    Determination of trace moisture in industrial fluoroalkanes (4)

    • Last Update: 2022-01-13
    • Source: Internet
    • Author: User
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    5.


    5.


    The test sample is introduced into the electrolytic cell as a gas: its moisture is absorbed by the moisture absorbent phosphorus pentoxide film in the cell , and it is quantitatively electrolyzed at the same time


    When the gas sample flow rate is 100mL/min at 25°C, 101.


    5.


    The schematic diagram of the micro-moisture analyzer is shown in Figure 4


    Figure 4 Schematic diagram of the electrolysis method trace moisture analyzer device

    5.


    5.


    For instruments that have been out of service or re-coated the electrolytic cell for a long time, they should be dried before measurement


    5.


    Place the control valve (9) in the "dry" position, slowly open the needle valve (13), and at the same time reduce the needle valve (12) (do not close it completely), and control the nitrogen flow at 20mL/min~50mL/min until The water reading value (volume ratio) of the meter head drops below 5, and the pressure reducing valve (4) is closed


    5.


    Use the four-way valve (6) to switch the dry gas source to the gas source to be tested, place the control valve (9) in the "dry" position, adjust the needle valve (13) to make the measured flow rate 100mL/min; adjust the needle valve (12) Set the bypass flow rate to 1000mL/uin, and record the reading after the water reading value (volume ratio) of the meter head drops below 5, which is the background value A of the instrument


    Switch the control valve (9) to the "measurement" position, keep the measurement and bypass flow unchanged, and record the reading after the meter head shows a relatively stable value


    5.


    The mass fraction of water in the sample w 3 , the value is expressed in %, calculated according to formula (4):

    w 2 =(BA)·K×10 -4 .


    Where:

    A——The value of the instrument background;

    B——The measured value of the sample;

    K——Conversion factor, calculated by the following formula
    .

    6 Allowable error

    6.
    1 Take the arithmetic average of the two parallel determination results as the determination result
    .

    6.
    2 The absolute difference between the two parallel determination results is shown in Table 1
    .

    Table 1 Absolute difference of measurement results

     

     

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