In the valve design or use of experience, lift-type valve filler mostly asbestos packing or graphite filler or PTFE v-type filler, but these kinds of fillers are limited by the number of valve hoist, that is, with the increase in the number of valve hoist, filler will wear, gap gradually increased, To a certain number of times (according to the statistics not more than 2000 times) the valve will be released from the filling place. After the leak, the packing gland needs to be compacted.
This scheme is suitable for the occasions when the valve is not many times.
If the valve frequency of open and close, (such as 10.3 million times a year), this undoubtedly increases the use of valves, maintenance costs. Is there a design that can still be sealed after 1.002 billion times?
The answer is yes. One way is to add a washer underneath the filler and a spring under the washer (the preload of the spring needs to be calculated), and when the filler is worn, the effect of the spring will be pressed again to seal the filler.
This method at present through the use of testing, can only reach 501 million times without leakage, the need for users in the annual overhaul, the pressure of the packing gland, can only reduce the usual maintenance. Another way, is to choose hydraulic, pneumatic sealing technology, change the original valve design ideas, in the filling place using oil cylinder seal slip ring, increase 0-type seal ring (need to calculate friction, sealing pressure, to determine the number of slip ring and 0-type seal ring). This method through the use, can reach 2 million times without leakage, but the 0-type sealing ring to aging, the use of only 5 years, at the same time higher costs.