The USA EPA has defined Low Leak Technology products are those that leak less than 100 PPMv (as determined by Method 21 techniques) over a reasonable lifetime.
For valve packing, the 2nd Edition of API 622 (to be released in 2011) will be the prominant test standard to meet the Low Leak Technology definition.
After the 2nd Edition of API 622 is released, this page will list the products (packing and valves) that meet these requirements.
