| 摘要 |
<p>This invention involves an improved ball-type check valve for use in conditions such as oil and gas drilling which involve abrasive fluids, high pressures, and high temperatures. In this improved check valve, a one-piece ball retainer is provided which consists of (1) a retainer ring for the ball, (2) a base, and (3) at least two vertical supports which connect the retainer ring and the base. Peripheral channels are formed by (a) orifices which pass between the vertical supports, adjoined to (b) recessed areas in the base. This allows the interior passageway (through the retainer ring) to be relatively large in relation to the peripheral channels. This has two effects. When downward flow begins, fluid velocity through the interior passageway is relatively high, which helps ensure rapid settling of the ball on the retainer ring. As downward flow continues through the peripheral channels, the small size of the peripheral channels causes continued high velocity, resulting in a relatively low pressure area below the ball compared to the pressure above the ball. This ensures that the ball remains securely settled on the retainer ring. The entire valve can be assembled in a free-standing housing, or in a standard collar or shoe used in drilling or workover operations. This improved valve is easier and less expensive to manufacture than valves having flexible skirts, and it can be used with any size casing or tubing.</p> |
