They are all good for a year.
Actually, the inspection interval is based on the frequency of use of the cylinder. The recommended inspection interval can be as frequent as monthly for heavily-used cylinders, or as infrequently as annually for rarely-used recreational cylinders.
Since, as an inspector, you don't have control over how the cylinder is used, you can't specifiy that the inspection is valid for one year. If, right after inspection, the user completely empties the tank and get salt water inside, how can say that your inspection is still valid for 12 more months?
Your inspection should certify only that it passed inspection while it was in your possession.
I think the vip sticker thing is a bunch of dive shop BS and if congress could get there heads out of their butts and pass tort reform life would be much better for all.
Actually, the VIP sticker "thing" developed as the result of an extensive research project conducted by the U.S. Navy. In the late 1960s a gelatinous corrosion product was found in a number of U.S. Navy aluminum scuba cylinders at a facility in Maryland. Concerned, the Navy inspected at total 1,336 aluminum cylinders. The inspection revealed that 16% of the cylinders were corroded, many with severe corrosion. Did cylinder corrosion degrade cylinder strength? The U.S. Navy consulted the Battelle Memorial Institute to investigate this, and other, questions about scuba cylinders.
One of the recommendations that arose from that Battelle study was -- annual scuba cylinder visual inspections.
If you want to read the original report, here it is:
http://http://www.stormingmedia.us/51/5182/0518217.html
Abstract:
A program was conducted to determine the cause of the corrosion that was discovered in a number of aluminum scuba cylinders, and to determine whether the rupture strength of the cylinders had been degraded by the corrosion. An examination was made of 68 corroded cylinders received from Naval facilities. Rupture experiments were conducted on new cylinders and on the most severely corroded cylinders. Detailed analyses were made of corrosion products from selected aluminum cylinders, and of corroded and uncorroded material from the ruptured cylinders. It was concluded that the corrosion in the cylinders examined had not significantly reduced the rupture strength of the cylinders. Recommendations were formulated concerning changes in manufacturing specifications, cleaning procedures, and inspection procedures to provide increased assurance that corrosion will not progress to the point of significantly degrading the rupture strength of aluminum scuba cylinders.
As a result of visual inspections, scuba cylinder now have a remarkably good track record. Other than the old cracking problems with the 6351 alloy, almost all major problems and fatalities have occurred with cylinders that did not have a current visual inspection, and, in almost all likelihood, wouldn't have happened had the cylidners been inspected regularly.
"He who forgets history is condemned to repeat it"
-George Santayana