We frequently get questions concerning the shelf life of our products. Shelf life is a term that can be defined differently by different manufacturers, and we explain what is the practice for Met-L-Chek. This information is also contained in the literature on the Met-L-Chek
web site. Met-L-Chek Company defines shelf life as the period of storage time, at ambient* conditions, during which an inspection material
will retain its functionality. The shelf life of most Met-L-Chek Company inspection penetrant materials is five (5) years from date of batch
approval. The shelf life of aerosol inspection materials is also 5 years provided that the aerosol propellant has not escaped and the can
still sprays. This shelf life period is exceeded by most materials and the 5 year period is provided only as a storage guide. Older materials performance may be verified through the Met-L-Chek Company.
Pen-Chek® recertification program. In fact tests done by Iowa State University and Sandia National Laboratories have shown that penetrant materials 10 years and older show no signs of degradation in performance due to age.
Now we come to the term “Tank life”. Once the containers of Met-L-Chek products have been opened, shelf life no longer applies. If the
product is in a tank or other container where it is used, the term “tank life” applies. For example, if a penetrant has a shelf life that expires on January 6, for example, and the penetrant was charged to a tank prior to that date, the product is OK to use. When January 6
has passed, the shelf life date has no meaning because the product is in a tank. Now “Tank life” is what counts. Continued usability of materials may be verified through the Met-L-Chek Company Pen-Chek® or MagChek™recertification program. The Pen-Chek® program
conforms to the requirements of AMS-2644E and ASTM E-1417. The Mag-Chek™ program conforms to the requirements of ASTM E-1444. For some applications, there are penetrant tanks that have Met-L-Chek products in them that are five or more years old. The
periodic tests show that the material is satisfactory to use, and there is no reason to discard the material and to replace it with fresh product.
The distinction between “Shelf life” and “Tank life” is important to make. For Met-L-Chek products that are in a tank and in use, there is no reason to discard the product and to replace it with fresh product if the shelf life has passed. Shelf life ha no further meaning once the product is in the tank.
This information is on the Met-LChek web site and may be easily reviewed there. Or, for clarification, please send us an email or phone us.