Measuring and testing – With fluid pressure – Leakage
Patent
1981-05-03
1984-01-24
Yasich, Daniel M.
Measuring and testing
With fluid pressure
Leakage
73 52, 209526, 209591, G01M 0332
Patent
active
044268769
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a method of and an apparatus for checking sealed containers of synthetic resin, paper, metal, etc. for pinholes (pinholes, cracks, etc.) which containers have enclosed therein a vaporizable material, such as a glucose injection solution, distilled water for injection, milk or oil, or a sublimable substance, such as naphthalene. (Such a material or substance will be referred to as a "vaporizable substance" in this specification and the appended claims.)
As a method of checking this type of containers for pinholes, containers have heretofore been checked for pinholes in a vacuum. The checking method has been used chiefly for detecting pinholes in sealed containers which contain a non-electroconductive liquid and which are not amenable to electrical checking.
This vacuum checking method is practiced by placing a sealed container in an airtight checking chamber, evacuating the chamber to a predetermined vacuum, thereafter stopping or interrupting the evacuation of the chamber and subsequently measuring the rise of the internal pressure of the chamber. The increased pressure value, when not lower than a predetermined standard value, indicates that the container has a pinhole since the increase of the pressure is attributable to the presence of a pinhole through which the enclosed substance vaporizes. (The term "vaporize" as used in the specification and the appended claims refers to the change of the above-mentioned vaporizable substance from the liquid state to the vapor or gaseous state, or from the solid state to the sublimation. The increased pressure value, if lower than the standard value, indicates that the container has no pinhole.
However, whereas the enclosed substance flows out from the pinhole of a defective container into the checking chamber during checking and remains therein, the method involves no expedient for effectively removing the remaining substance. The remaining substance vaporizes again in a vacuum during the next checking cycle, consequently increasing the internal pressure of the checking chamber to the standard value or higher to erroneously indicate that the sealed container subsequently checked has a pinhole even when free from any pinhole. If the standard value is set at a higher level to avoid such erroneous detection, there is the likelihood that a container with a pinhole will be accepted as a faultless one.
Futher aside from the substance flowing out through a pinhole and remaining in the checking chamber, a vaporizable substance will adhere to the surface of a sealed container before checking for one reason or another. The adhering vaporizable substance also vaporizes during checking to act as a disturbance (noise). The checking result is then likely to indicate that the container has a pinhole even if having no pinhole. Additionally another trouble arises in that the substance will flow off the surface of the container and similarly remains in the checking chamber to act as a disturbance during the subsequent checking cycle.
If it is attempted to completely remove the remaining vaporizable substance from the checking chamber after checking in preparation for the following checking cycle, the checking chamber must be evacuated for a prolonged period of time. This leads to an inefficient checking operation and is objectionable especially to a continuous operation for checking large quantities of sealed containers.
An object of the present invention is to provide a method of and an apparatus for checking sealed containers for pinholes accurately and efficiently in a state substantially free from disturbances.
According to the invention, this problem is solved by "a method of checking sealed containers for pinholes with a vaporizable substance enclosed therein characterized by placing the sealed container into a first chamber, hermetically closing the first chamber, evacuating the first chamber to a vacuum by vaporizing vacuum suction means connected to the first chamber to vaporize a vaporizable substance off the surface of the sealed container, subst
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patent: 3973249 (1976-08-01), Yokota et al.
patent: 4331722 (1982-05-01), Packo et al.
Otsuka Pharmaceutical Factory Inc.
Yasich Daniel M.
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