Patent Application
20070186399
Gases used in industrial processes, such as the manufacture of integrated circuits on silicon substrates, must be maintained at a high level of purity to ensure that they remain chemically active and furthermore do not contaminate the workpiece upon which they are used. The gases are often highly reactive and hazardous, and even minute amounts of moisture, oxygen or particles can have a significant adverse effect and are to be avoided.
The gases are stored in a compressed state in tanks, which have various valves, seals and fittings necessary to connect the tanks to other equipment that use the gases in the manufacturing processes. While the valves, seals and fittings are designed and manufactured to maintain the high degree of gas purity required, a challenge arises when coupling and uncoupling the fittings because there is the potential to introduce the aforementioned contaminants into the gases. This problem is effectively avoided by allowing a purge gas to flow from a fitting while it is disconnected, the purge gas effectively preventing moisture, oxygen or particles from entering the fitting and posing a contamination problem until the fitting is reconnected fluid-tight to another component.
The purge gas flow occurs at pressures between about 10 psi and 20 psi above atmospheric pressure. This relatively high pressure makes it difficult to manually install a seal in a fitting prior to attachment to a mating fitting. When the seal is seated manually it is difficult to keep the opening in the seal clear, as a finger or a thumb must apply force to the seal to properly seat it within the fitting. With the seal opening obstructed during seating, purge gas pressure builds up behind the seal, which often pops out of the fitting as a result of the purge gas pressure when the installing force is removed.
To further complicate the seal installation process, technicians often must wear bulky protective clothing due to the hazardous nature of the gases. The clothing includes gloves that prevent contamination of the seal and other hardware but also reduce tactile sensation and thus make it difficult to deftly handle the seals. Additionally, the fittings are often recessed within housings and are not visible when a seal is being installed. These complications result in lost seals, as seals are dropped during installation or ejected from the fitting due to purge gas pressure build-up, and cause significant lost time and added expense to the industrial process in which the gas is used. There is clearly a need for a tool and a method to facilitate installation of seals in fittings through which purge gas is flowing.
The invention concerns a tool for installing a seal in a fitting. The tool comprises a sleeve having a first socket sized to receive the seal, and a second socket positioned adjacent to the first socket. The second socket defines an open end of the sleeve and is sized to receive the fitting. A pusher element is movable within the sleeve. The pusher element has a contact surface engageable with the seal for moving the seal out of the first socket and into the fitting when the pusher element is moved relatively to the sleeve.
Preferably, the pusher element comprises a shaft having the contact surface at one end. The shaft has a conduit therein. The conduit has an inlet positioned at the one end providing fluid communication with the fitting, and an outlet providing fluid communication with the atmosphere. The outlet allows gas to escape from the fitting to the atmosphere when the second socket is engaged with the fitting. A handle is attached to the shaft in spaced relation to the sleeve. A biasing element is positioned between the sleeve and the handle. The biasing element biases the sleeve in a direction away from the handle.
The invention also includes a method of installing a seal in a fitting through which gas is flowing. The method comprises:
A radial spring 18, also preferably formed of stainless steel, is positioned within a groove 20 circumferentially around the seal. The radial spring 18 may comprise an oversized split ring having a gap that allows the ring to be radially flexible. The radial spring provides a flexible element that exerts a force directed radially outwardly when it is compressed radially inwardly. Radial spring 18 frictionally retains the seal 10 within the fitting 12, the fitting having an opening 22 that is smaller in diameter than the diameter of the radial spring 18. When the seal 10 is inserted into the opening 22, the fitting sidewall 24 radially compresses the spring, which pushes back and frictionally holds the seal within the fitting.
To prevent contaminants such as moisture, oxygen and particulates from entering the fitting 12 when it is not coupled to another component, purge gas is permitted to flow through the fitting 12 from tank 14, the gas flow being controlled by a purge gas valve 28 between the tank and the fitting. To facilitate installation of seal 10 into fitting 12 while purge gas is flowing through the fitting, a tool 30 is used. Tool 30 comprises a sleeve 32 having a first socket 34 sized to receive and hold the seal 10. The diameter of socket 34 is smaller than the radial spring 18 so that when the seal is inserted within the socket it is frictionally retained therein by the radial spring action.
Sleeve 32 has a second socket 36 positioned adjacent to the first socket 34. The second socket has a larger diameter than the first socket and defines an open end 38 of the sleeve. The second socket is sized to co-axially receive the fitting 12 through the open end 38, and the first and second sockets cooperate to align the seal 10 with the opening 22 in fitting 12 for installation of the seal against the seat 16.
A pusher element, preferably in the form of a shaft 40, is axially movable within the sleeve 32. Shaft 40 has a contact surface 42 at one end 44 that is engageable with the seal 10 seated within the first socket 34. Sleeve 32 is retained to the shaft by an O-ring 46 mounted within a groove 48 positioned near the end 44 of the shaft 40. The O-ring has a greater outer diameter than the shaft and engages a shoulder 50 within the sleeve, the interaction between the shoulder and the O-ring limiting the motion of the sleeve toward end 44, preventing the sleeve from falling off of the shaft. Other retaining elements, such as snap rings and the like are also feasible.
A handle 52 is attached to the shaft 40 in spaced relation away from the shaft end 44. The handle may be formed from a polymer resin and is sized and shaped to ergonomic advantage to provide a good manual grip. A biasing element, preferably in the form of a compression spring 54 is positioned between the handle and the sleeve. Spring 54 biases the sleeve 32 away from the handle 52, pushing the shoulder 50 against the O-ring 46 and holding the contact surface 42 at the end 44 of shaft 40 in spaced relation from the seal 10 when it is held in first socket 34.
The shaft 40 also has a conduit 56 positioned within it (see also
In operation, as shown with reference to
As shown in
It is advantageous to make the sleeve 32, shaft 40 and spring 54 from stainless steel to provide a robust tool that is substantially inert and therefore will not be a significant source of contamination. Other materials are also feasible. O-ring 46 may be a flurocarbon compound, such as polytetrafluoroethylene for its inert and low-friction qualities as well.
