Valves and valve actuation – Rotary valves – Ball valve
Reexamination Certificate
2001-06-08
2002-12-03
Fox, John (Department: 3753)
Valves and valve actuation
Rotary valves
Ball valve
C137S246160
Reexamination Certificate
active
06488265
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to ball valves and more specifically, to ball valves used as intake, in-line or discharge valves for fire pumps and firefighting apparatuses.
BACKGROUND OF THE INVENTION
In firefighting apparatuses, ball valves are used at both the intake and discharge outlets for firefighting pumps as well as in in-line positions in the piping of a firefighting unit. Over periods of time, the seals of the ball valves tend to adhere to the ball component of the valve unit. Further, mineral deposits such as dirt or grit may deposit on the ball component. Depending upon the environment and the specific media flowing through the valve, the valves may become extremely difficult to open. Further, because the ball valves are often disposed in areas with little space, the ball valves must be provided with relatively short handles that transmit little torque to the valve. As a result, only firefighters with superior physical strength are able to open and close ball valves that have accumulated dirt and grit on the ball component.
The only way to overcome the above problem is to lubricate the valve seat or seal as well as the ball component. Unfortunately, due to space constraints on firefighting apparatuses, the ball valves may be disposed in inconvenient places or buried underneath other operating elements of the firefighting apparatus. As a result, the ball valves may be difficult to obtain access to which makes them very difficult to lubricate. Typically, the firefighting apparatus must be pulled out of service and the lubrication performed by qualified mechanics.
Another way to overcome the above sticking problem has been to utilize a plastic ball component and plastic seat elements. The plastic elements are typically fabricated from ultra-high molecular weight polyethylene which is considered self-lubricating. Unfortunately, this solution presents its own shortcomings because polyethylene is susceptible to deterioration from rust, grit and other mineral deposits that form on the ball component. Specifically, when the valve is opened and closed, the deposits on the ball component score and cut into the valve seat and/or the ball component itself thereby resulting in leakage and/or valve failure.
Another approach utilizes a soft elastomer for the seal element as opposed to the rigid polymer or high molecular weight polyethylene discussed above. Soft elastomer material is available that is resistant to tears and cuts. Further, soft elastomers can be impregnated with lubricants which further enhance their performance and operating life. However, it has been found that the use of soft elastomers still results in the sticking problem discussed above and has not reduced the amount of torque required to open or close a ball valve that has been in service for an extended period of time.
Further, another problem associated with the use of soft elastomers as seal elements is that soft elastomers often fail to provide support for the ball component of larger valves, such as valves with ball components having diameters greater than two inches. It has been found that, with the use of larger ball components, an increased amount of seal pre-load must be applied between the ball and the seal element in order to provide the support necessary for the ball component. As a result, the increased amount of seal pre-load that is required also increases the amount of torque necessary to open and close the valve. Further, the stress resulting from the increased seal pre-load can also lead to premature failure of the soft elastomer seal.
As a result, both the rigid polymer valve seats and seals and the soft elastomer seals each have their associated shortcomings. Both types of seals are susceptible to premature damage and failure. Further, once any seal of a ball valve is damaged, the valve must be repaired and, as discussed above, this often requires removing the firefighting apparatus from service. It has also been suggested to employ seal elements on both sides of the ball component; however, this further exacerbates the problem of the torque required to open and close the valve once the valve has been in use for a sufficient time to accumulate dirt, grit and other mineral deposits on the ball component.
Another problem associated with the ball valves used in firefighting apparatuses is the inflexibility of the mounting of the ball valve. Specifically, due to cramped space requirements on firefighting apparatus, it is often difficult to mount the actuator of the valve in a position where it can be utilized by firefighting personnel. One solution to this problem has been to make the actuator positioning adjustable in 90° increments or in 45° increments by using various adaptors between the valve body and the actuator. Further, the servicing of valves often proves difficult because the bolts required to mount the actuator on the valve are often difficult to obtain access to in the cramped environment of today's modem firefighting apparatuses. Still further, the typical installment of such valves requires four bolts disposed on each side of the valve that are used to mount the valve between the pump and a conduit or in-line between two pieces of conduit. The use of these bolts disposed on either side of the valve add to the overall effective length of the valve which is disadvantageous due to the limited space availability on firefighting apparatuses.
Still another problem associated with current ball valves of firefighting apparatuses is specifically associated with large diameter hoses which are desirable because they provide increased water flow to the fire. As noted above, larger hose diameters require larger ball valves which, in turn, as discussed above, are prone to premature failure and leakage. Further, when larger diameter hoses are employed, they present their own hazards because they typically have lower pressure ratings than smaller hoses. This problem is exacerbated if the flow of water or firefighting material is shut off at a downstream location. The resulting increase in pressure in the hose can cause the hose to snap and fling violently.
As a result, one solution to this problem has been to locate a remote adapter containing a relief valve on the pump discharge outside of the pump housing or the panel that surrounds the pump. However, this solution creates its own problem in that the relief valve must also be located outside of the housing or panel as well. Another solution is to provide a portable unit outside the pump panel (containing a relief valve) for that line.
However, the location of the relief valve outside of the panel is dangerous because the release of exhaust water from the relief valve poses a safety hazard to firefighting personnel. Further, in the event the relief valve fails, there is no protective panel or housing between the failed relief valve and the firefighting personnel. Still further, the relief valve is exposed, thereby making it accessible to being tampered with, particularly the relief valve pressure setting. For example, an inexperienced person may reset the pressure to a level above the safety limits of the hose and/or firefighting industry standards. Still further, placement of the discharge outlet and relief valve outside of the housing panel results in the discharge outlet and relief valve extending outward beyond the body of the firetruck, which poses a significant driving hazard.
Accordingly, there is a need for an improved seat and sealing element for ball valves which will result in a reduction in the amount of torque required to operate the valves, which reduce the likelihood of premature leakage and which reduce the likelihood of premature failure of the ball valve. Further, there is a need for an improved ball valve design which provides greater flexibility in mounting the ball valve so that the actuator and the ball valve itself can be more readily accessed after installation for both operation and maintenance. Still further, there is a need for an improved system and method for lubricating ball
Laskaris Michael A.
Sadler Jeffrey B.
Akin Gump Strauss Hauer & Feld L.L.P.
Fox John
Hale Products, Inc.
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