Three Factors Affect the Quality of PN Swellable Waterstops

Volume expansion rate test

All our waterstops are manufactured in accordance with national standards and have undergone strict tests before leaving the factory to ensure high quality. However, the quality of waterstops on the market varies widely. You may use the following method to check whether PN swellable waterstops are qualified.

  • Flow at high temperature

    Place three samples with a dimension of 20 mm × 20 mm × 4 mm on a grooved wooden frame that inclines at 75° with 2 mm thickness in the groove and 2 mm thickness outside the groove; put these samples into a drying box at 80 °C and take them out after 5 h. Observe whether these samples flow obviously. If the flow trace falls within 1 mm from the groove edge, it is considered as no flow.

  • Low temperature test

    Put two samples with a dimension of 50 mm × 100 mm × 2 mm in a low temperature box at -20 °C for 2 h. Wind these samples around a round rod with a diameter of 10 mm after taking them out. Observe whether they are fragile.

  • Volume expansion rate

    You may test the volume expansion rate according to the following steps.

    • Prepare 3 samples with 20±0.2 mm in length and width and 2±0.2 mm in thickness respectively. When making samples from finished products, remove the surface layer as much as possible.
    • First weigh the mass of prepared samples in the air with a balance with an accuracy of 0.001 g, and then weigh the mass of samples suspended in distilled water.
    • Immerse these samples in 300 ml distilled water at 23±5 °C. During the test, avoid sample overlap and water evaporation.
    • Immerse samples for 72 hours and weigh their mass in distilled water with the balance mentioned above. Take them out and then lightly absorb the moisture on the surface of samples with filter paper. Weigh the mass of samples in the air.

    The average value of three samples is taken as the volume expansion rate, and is calculated as follows:


    • △V stands for volume expansion rate, expressed in %;
    • m1 stands for mass of samples in air before immersion, expressed in g;
    • m2 stands for mass of sample in distilled water before immersion, expressed in g;
    • m3 stands for mass of samples in the air after immersion, expressed in g;
    • m4 stands for mass of the sample in distilled water after immersion, expressed in g;
    • m5 stands for mass of the pendant that is used to suspense samples immersed in water, expressed in g.

    When the test results are obtained, compare them with the following table. Those that meet the following technical data are considered as qualified:

    Material Name Test Item PN-150 PN-220 PN-300
    PN Swellable Waterstop Volume expansion rate (%, ≥) 150 220 300
    Flow at high temperature (80 °C, 5 h) No flow No flow No flow
    Low temperature test (-20 °C , 2 h) No fragile No fragile No fragile

    Only when all technical indicators are met, it can be deemed as qualified. If an indicator fails to meet the technical requirements, double samples shall be prepared for retest. If the test result is unqualified, this batch of products is considered as unqualified.

All our products are produced in strict accordance with national standards, and each batch of products will be tested before leaving the factory. Corresponding test report will be provided, you can buy these waterstops without worry.

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