DE1808234C3 - Method for determining the water vapor permeability of closed packages and containers - Google Patents

Description

The invention relates to a method for determining the water vapor permeability of closed ones Packs and containers with moist contents in which the pack is placed in an enclosed space will.

Previously known methods are based on either the weight loss of the pack during storage To be determined under standard climatic conditions or one from the package with destruction of the same To take a sample of the atmosphere inside and to analyze it.

Meanwhile, the first-mentioned method, especially in the case of relatively tight packings, in terms of sensitivity is very limited, as the ratio of the weight of the package or the container together The second method is the content that is very unfavorable for weight loss, according to which water vapor permeation is not non-destructive, and the atmosphere inside the pack is mostly created by taking a sample changed so that well-defined relationships are no longer available for subsequent analyzes.

The invention aims to provide a more accurate and sensitive non-destructive measurement method for this type of test create.

The inventive method is characterized in that the pack in the closed The room is first flushed with dry air and that with the help of a humidity sensor and a suitable one Circuit the time interval is measured, which elapses until the volume of air outside the pack in the closed According to space, water vapor permeates from the pack around a certain, exactly between

two limit values defined amount until it is moistened.

In the following Figure 1 is the inventive Method explained in more detail using a schematic representation of an exemplary embodiment

An example to be tested soft pack 24 with a content 23 which by welding the outer edges 22 of the packaging material is enclosed in a two-part measuring chamber This measuring chamber consists of a lower one

ίο Part 8, which, for example, for thermostatting is made double-walled with the aid of a circulation thermostat 17, the thermostating fluid 25 can circulate between the two jackets and connected to Aaischlußkupplungen 21 in the double

walled coat enters or exits, and a perforated Contains bottom SO on which the pack can be placed.

A cover 4 is placed on the lower part 8, which by a round cord rubber ring 5 against the

sen lower part seals, this cover being screwed together with the lower part of the measuring chamber 8 with the aid of screw caps 6 and easily operated knurled or wing nuts 7.
A fan motor 13, which is attached outside this space and whose VVcüc is passed through the wall tightly, ensures the circulation of the air flow inside the enclosed space formed in this way, with a blade 12 at the other end of the shaft inside the measurement space formed

Air circulation is attached.

The air flow is directed by a guide plate 11 so that that it passes the pack 24 and hits the humidity cell 2, the active layer 1 of which is practically fills the whole lid.

The measurement signal from this moisture sensor 2 is sent to a signal converter via lead electrodes 3 and amplifier 18, which in turn when a certain signal is reached corresponding to the lower Limit the Feuchtemeßintervalls a synchronous timer 19 sets in operation and this when reached of the upper limit value of the moisture measurement interval, whereby the during this time interval generated pulses are displayed on a counter 20.

The thermostatically controlled measuring space is thermally separated by a heat insulator 9.

The dry air required at the beginning of the experiment is sucked in from the environment by a pump 16 and with the help of a cartridge with desiccant

Filling 15 dried. This air is via an electromagnetic Valve 14 let into the measuring space 27, washes around the test specimen and leaves the measuring space 27 again through a valve 26 to the outside. The two valves 14 and 26 are of course closed tightly during the measurement.

F i g. 2 shows a schematic '; Representation of the arrangement of the electrodes 2 on the moisture-sensitive layer 1, for example the moisture sensor with Advantage is made so large that it is practically over the entire uppermost boundary surface of the measuring space is enough, since water vapor is lighter than air and so in the case of insufficient air circulation the one that has passed through Water vapor will always hit the probe, while in the case of a smaller probe the If there is insufficient air circulation, water vapor could remain trapped somewhere away from the sensor.

1 sheet of drawings

Claims (5)

Patent claims: t. Procedure for the determination of the water vapor permeability of sealed packs and containers with moist contents in which the pack is brought into an enclosed space, characterized in that the pack (24) in the closed space (8,4) is first flushed with dry air and that with the help of a Humidity sensor (2) and a suitable circuit (18) the time interval is measured that passes, until the volume of air outside the pack (24) in the closed space (8, 4) results in the passage of water from the pack (24) by a certain, precisely defined between two limit values Amount is moistened. 2. The method according to claim 1, characterized in that for measuring the moisture in the completed Room (8, 4) a humidity sensor (2), which in its dimensions is the uppermost boundary surface of the space (8, 4) is used. 3. The method according to claim 1, characterized in that the time measurement is carried out analogously. 4. The method according to claim 1, characterized in that the time measurement takes place digitally. 5. The method according to claims 1 to 4, dadurrh marked that the result of the timing is registered.