1. Field of the Invention
This invention pertains to high pressure valves, particularly to high pressure valves which operate by directing flow to a dump outlet. With still greater particularity, this invention pertains to high pressure dump valves that are usable as a rotary joint.
2. Description of the Prior Art
Water jet cutting equipment requires the use of extremely high fluid pressures. Pressures in the range of 20,000-100,000 psi are not uncommon. At such pressures, conventional valves are useless, due to erosion at the seals, and, leakage. Accordingly, a number of valves have been devised which use the compression characteristics of materials at high pressures and counter balancing forces. Valves of this type, however, require high actuation forces to overcome the hydrostatic forces on the operating parts to actuate the valve. For this reason valves for high pressure use have required auxiliary activator systems, such as, solenoids or pneumatic activators to provide sufficient force to operate valves. Accordingly, a need has arose for a valve that may be constantly subjected to ultra high pressures, and requires a small actuation force.
Recent advances in high pressure technology have made water jet drilling of hard surfaces a reality. In such drilling, a high pressure jet at an angle to the surface face is rotated and advanced. A high pressure rotary joint is required for this device, to allow supply of high pressure fluid to the rotating jet. The joint is subjected to constant high pressure and movement. The swivel must still seal under these conditions.
In water jet drilling apparatus it is desirable that the assembly be as simple as possible. First, the simpler the apparatus is, the more lightweight, and, therefore, portable. Second, simplification of the apparatus reduces the chance of malfunctions, and increases durability. For these reasons it would be desirable to combine the functions of rotary joint and on-off valve in one piece of apparatus.