| 摘要 |
The invention relates to an improved valve of the double block and bleed type construction wherein a pair of independently and externally actuable ball valves are provided as a contigency measure within the valve to prevent catastrophic valve failure. The valve is comprised of a first valve assembly housing the first ball valve, and a second valve assembly housing the second ball valve, each said ball valve being held within the particular valve assembly by an annular retainer component. Each valve assembly has a passage through which fluid can pass when the ball valve is in an open condition, and also a mating surface which is brought to bear against the mating surface of the alternate valve assembly to form a valve with a single joint. A single joint double block and bleed valve can only be compromised around that single joint, and therefore the valve configuration according to the invention is the safest achievable without removing the inherent facility for simple ball valve or assembly replacement. |
