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Labthink International, Inc. - Medford, MA

Original Press Release

Barrier Property Testing of High Transmission Rate Materials

Press release date: Jun 19, 2014

1. Differential Pressure Method
The accuracy of differential pressure method testing is mainly decided by the data obtained from the pressure sensor in the lower chamber. When testing high transmission rate specimens, only the pressure sensor with excellent sensitivity and precision can be suitable for the rapid pressure changes.

As to differential pressure method testing, measuring range can be expanded with the help of the following means:
First, to change the testing mode. Owing to the fact that high transmission rate materials would achieve equilibrium in a very short period of time, the pressures at the beginning and the end of the test can be preset. Then, gas transmission rate of the material can be calculated by measuring the time between pressure changes. According to experiences, measuring range can be expanded in this way; and data repeatability can be greatly improved. Yet, owing to the rapid pressure change, only automatic testing instruments can be used for such high transmission rate materials. The fuzzy testing mode, installed in Labthink PERME V series differential pressure method transmission rate testers, can realize high transmission rate specimen testing.

Second, to change the testing area with the MASK fittings. By changing the testing area, the amount of testing gas through the specimen within a unit time can be effectively regulated. Labthink is now supplying her customers with an efficient and convenient MASK fitting, which has several selectable transmission areas.

2.Equal Pressure Method
Gas sensor of equal pressure method instrument directly outputs the gas quantity inside testing chamber. An over-range would directly influence life span of the sensor. So, for equal pressure method, reducing testing gas quantity inside the testing chamber within a unit time is the key for high transmission rate testing. There are three ways as follows:

First, to change the testing gas. Generally, the measuring range is expanded by reducing the oxygen concentration differences between the two sides of the specimen. For example, to replace pure oxygen with air or with other mixed gases. When calculating, the concentration of testing gases should be converted.

Second, to speed up purging speed of the carrier gas, so as to reduce testing gas concentration inside testing chamber. Since the testing gas quantity is obtained from both testing gas concentration and purging speed of the carrier gas, the accelerating purging speed of carrier gas would not influence the testing data.

Third, to change the testing area with MASK fittings, so as to reduce quantities of testing gas transmitted through the specimen within a unit time.

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