Measuring and testing – With fluid pressure – Leakage
Reexamination Certificate
1999-04-22
2001-03-27
Larkin, Daniel S. (Department: 2856)
Measuring and testing
With fluid pressure
Leakage
C079S003000
Reexamination Certificate
active
06205847
ABSTRACT:
TECHNICAL FIELD
This invention relates to a method of testing for a leak to check on whether there is a leak or not in the wall of the inner vessel of a double blow molded bottle made of a synthetic resin or resins, wherein said bottle is molded by laminating peelably the outer vessel comprising the outer shell of a fixed shape with the inner vessel comprising a deformable inner bag, so that liquid contents can be poured out without any change in outer appearance of the bottle and yet open air is prevented from invading the inner vessel of the bottle.
BACKGROUND OF THE INVENTION
A conventional method of testing for a leak with this type of double blow molded bottles involved testing the entire bottle for any leak, as by means of pressure measurement inside the bottle.
Because the aforementioned conventional leak testing method involves testing the entire double blow molded bottle for any leak, it was impossible to test these bottles for a leak unless each of the outer and inner vessels has a leak at the same position of the bottle. The leak test could not be conducted if the inner vessel alone had a leak.
SUMMARY OF THE INVENTION
This invention has been made to solve the aformentioned problems found in prior art. An object of this invention is to make it possible, technically, to detect any leak in the inner vessel of a double blow molded bottle, where the liquid contents are received. Another object of this invention is to supply users stably with the double blow molded bottles made of synthetic resins of consistent quality.
DETAILED DESCRIPTION OF THE INVENTION
In the invention there is provided a method of testing for a leak with the inner vessel of a double blow molded bottle, wherein said bottle comprises an outer vessel of a synthetic resin or resins forming the outer shell of a fixed shape and an inner vessel in the form of an inner bag of a flexible synthetic resin or resins, said inner vessel being peelably laminated inside the outer vessel, and wherein said bottle has an opening to enable the space between the outer and inner vessels to be exposed to the outside.
According to this invention, an air channel is formed between the outer and inner vessels by deflating and peeling the inner vessel from the outer vessel and by securing air flow through the opening of this air channel.
The existence or non-existence of a leak in the inner vessel is judged by supplying air to the inner vessel at a given micropressure and by observing, after a certain period of elapsed time, whether or not the pressure inside the inner vessel reaches a predetermined level which has been set from a test conducted under the same conditions using a bottle with no leak through the inner vessel wall.
When test air supplied to the inner vessel begins in its deflated state, the pressure inside the inner vessel reaches a set pressure level after a certain period of elapsed time, if the inner vessel has no leak.
In contrast, if the inner vessel has a leak, there inevitably follows a flow of test air through the leak. Even if the rate of air flow through the leak in unit time is lower than the test air supply rate and if it is possible for the pressure inside the inner vessel to reach the preset level, it takes a longer period of time to reach that level than the preset period. If the air leak rate is higher than the air supply rate, the pressure inside the inner vessel would never reach the preset pressure level.
Therefore, it is preferred to make measurements in advance on a relationship between the time of test air supplied and the pressure inside the inner vessel for the bottle with no leak in the inner vessel, and based on this relationship, to set certain period of time and the level of pressure. If the set pressure is reached within the set period, then the bottle is judged as having no leak. If the pressure is not reached, the bottle has a leak.
At that time, it is necessary to secure the air flow through the channel opening during the test. If the air channel is closed, the air existing in the space between the outer and inner vessels is not dischaged outside, and the pressure inside the bottle (not inside the inner vessel) sharply rises, regardless of the existence of a leak through the inner vessel. As a result, the test becomes impossible.
These settings of time and pressure differ, depending on the bottle size and shape, the material of the inner vessel, the pressure of supplied air, and the like. Therefore, measurements are required for each type of bottle to be tested, to set optimum levels for respective bottles. Since test air is supplied at a micropressure, the difference in the pressure inside the inner vessel caused by the leakage can be readily observed as an obvious change.
As the criteria for time and pressure settings, it is preferred to select the stage in which the deflated inner vessel starts to swell. During this stage, the pressure inside the inner vessel having no leak undergoes a sharp change (a pressure rise) as test air is fed thereto.
In the invention, there is provided a specific structure in which the opening is put in the wall of the outer vessel.
The invention makes it possible to deflate and deform the inner vessel while securing an assembly of outer and inner vessels at the mouth portion of the bottle, without the use of any cap or other parts. The test procedure gets all the more simple.
In the invention, there is provided a laminated structure for at least one of the outer vessel and the inner vessel and the layer comprising the interface between this laminated vessel and the other vessel is given high peelability against the opposite layer.
When the inner vessel is peeled from the outer vessel, the invention makes it possible to obtain steady and smooth peeling movements of the inner vessel in a manner giving full play, without any difficulty, to the function required for the entire bottle or for each of the outer and inner vessels, by giving a laminated structure to the outer vessel and/or the inner vessel. With smooth peeling secured, the inner vessel can be stably deflated and deformed in a certain shape, and the leak test with the inner vessel can be conducted with increased precision.
REFERENCES:
patent: 4055984 (1977-11-01), Marx
patent: 63-35340 (1989-02-01), None
patent: 10-156928 (1998-06-01), None
Larkin Daniel S.
Oliff & Berridg,e PLC
Yoshino Kogyosho Co. Ltd.
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