In fast shut butterfly valve design or using experience in the, lifting type fast shut butterfly valve filler more for asbestos packing or graphite filler or poly four fluoride v type filler, but this several filler are by fast shut butterfly valve opening and closing times of limit, is with fast shut butterfly valve opening and closing times of increased, filler will wear, clearance gradually increases, to must times (according to statistics not over 2000 times) fast shut butterfly valve will will from filler at produced leaked. Leak will need to be pressed again after the packing gland.
Is there any way to fast closing butterfly valve open and close after 1.002 billion, still has the perfect seal? The answer is Yes.
The first approach is that packed below the add a washer under the washer and spring (spring preload needed), when packing wear, due to the function of the spring, it will again press the packing, fast closing butterfly valve sealing. This approach through the use of tests, only opening and closing 501 million not to divulge, require annual overhauls, again press the packing gland, it can only reduce the usual maintenance.
The second approach was selection of hydraulic and pneumatic seals, change the fast closing butterfly valve design, sealing the fuel tank to use at packing slip ring, an increase of 0-rings (friction and sealing pressure needs to be calculated to determine the slip ring and the number of 0-rings). This approach by using, to achieve open and close 2 million is not revealed, but the 0-ring to aging, using only 5 years, and higher costs.