High flow check valve apparatus

A check valve apparatus is provided for high volume fluid conduits such as a casing string of an oil well. In order to maximize the fluid delivered from the well, it is essential that the restrictions imposed on the fluid flow path by necessary components in the casing string, such as a standing check valve, provide as little as possible interference with the flow area. This invention provides a valving arrangement including longitudinally extending, separated, parallel fluid inlet and outlet passages interconnected by a plurality of ball valve chambers, with each chamber defining a transverse ball seat and containing a ball cooperating with such seat. The fluid area of the inlet passage decreases from the first chamber to the last in the direction of fluid flow while the fluid area of the outlet passage increases from the first chamber to the last, so that the total fluid area passage through the plurality of valves in their open position is maximized.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to a check valve apparatus, and particularly to 
standing check valve for use in oil wells. 
2. Description of the Prior Art 
The world's energy demands have placed an increasing emphasis on maximizing 
the amount of oil pumped from each producing well. Obviously, the volume 
of oil to be pumped from a well is first limited by the interior diameter 
of the well casing or other conduit. A secondary limitation on the maximum 
fluid flow from the casing is the necessity of incorporating protective 
apparatus in the casing, such as a standing check valve which is normally 
disposed in the bottom portion of the casing beneath the pumping apparatus 
to permit the pumping apparatus to be removed or shut off without losing 
the column of oil previously pumped and existing in the casing. A ball 
valve has been preferred for such check valving apparatus inasmuch as it 
is extremely reliable and is not apt to hang up in the opening position or 
fail to achieve a proper seal in its closed position. However, the 
conventional ball valve does provide a substantial impairment to fluid 
flow in its open position and there is a need therefore for a check 
valving apparatus having the reliability of a ball valve, but yet 
providing substantially increased fluid flow area in the open position of 
the valve apparatus. 
SUMMARY OF THE INVENTION 
In essence, this invention contemplates providing a plurality of check 
valves within an oil well casing but arranging the fluid inlet and outlet 
passages to the respective chambers containing the ball valves in such 
fashion that the area available for fluid flow through the valves in their 
open position is maximized. This is accomplished by providing parallel, 
axially extending separated inlet and outlet fluid passages in a tubular 
housing and interconnecting such passages by a plurality of ball valve 
chambers, each of the chambers defining a ball seat and having a ball 
disposed therein cooperating with the seat. The inlet passage has as large 
as possible fluid passage area entering the first ball valve and a 
decreasing fluid passage area entering each of the successive ball valves. 
Conversely, the outlet passage has a relatively small fluid passage area 
communicating with the first of the ball valves but increases in area as 
it communicates with each successive ball valve chamber so as to maximize 
the fluid flow through the check valve apparatus when the ball valves are 
in their open position. 
Accordingly, it is an object of this invention to provide an improved check 
valve apparatus providing a maximum fluid flow through the valve when the 
valve apparatus is in its open position. 
A particular object of this invention is to provide a maximum flow check 
valve apparatus in the form of a tubular housing which is sealingly 
mountable within an oil well casing or other conduit and provides an 
optimum fluid flow through the check valve when the valve is in its open 
position. 
Further objects and advantages of this invention will be apparent to those 
skilled in the art from the following detailed description.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring to FIG. 1, numeral 10 indicates the outer housing of a standing 
valve assembly which is conventionally mounted in the lower end portions 
of the production casing of an oil well, generally immediately below the 
pumping apparatus. While the construction shown in FIG. 1 indicates that 
the entire valve housing is fabricated from a unitary piece of metal, 
those skilled in the art will recognize that this is merely a schematic 
presentation of the valving apparatus, and that various components of the 
housing will be separately fabricated and then assembled by brazing or 
axial stacking to provide the unitary structure shown. 
The housing 10 has a large inlet passage 11 at its bottom end and an 
equally large outlet passage 12 at its top end. Extending upwardly from 
the inlet passage 11 is a continuation inlet passage 13 which is of 
semi-annular cross-sectional configuration, as best shown in FIGS. 2 
through 4, and gradually decreases in cross-section as it extends 
upwardly. On the opposite side of the housing 10, a continuation outlet 
passage 14 is provided which extends downwardly from the outlet passage 
14, and is of semi-annular configuration, as best shown in FIGS. 2 through 
4 and this passage decreases in cross-section as it extends downwardly. 
Continuation inlet passage 13 and outlet passage 14 are entirely separate 
and are interconnected only by a plurality of axially spaced valve 
chambers 15. Each chamber 15 includes an annular ball seat 16 and an 
inverted cup shaped ball enclosure wall 17 which prevents the ball 18 from 
moving sufficiently far from its seat that it will not readily reseat upon 
a reversal of flow through the ball valve chamber 15. 
While the embodiment specifically illustrated in the drawings employs three 
such ball valve units, the number of valve units is a function of the 
desired total fluid passage area available in the standing valve apparatus 
when all the balls are in an open position. When the balls 18 are in an 
open position, due to the fluid pressure in the inlet passage 11 being in 
excess of that existing in the outlet passage 12, the total fluid passage 
area through the apparatus is primarily measured by the largest area 
portion of the inlet continuation passage 13 plus the smallest fluid 
passage area of the outlet continuation passage 14, i.e., the total areas 
of passages 13 and 14 as shown in cross-section in FIGS. 2-4. This total 
fluid area remains constant, irrespective of the number of valves 
incorporated in the apparatus, due to the fact that the area of the 
continuation inlet passage is decreasing at the same rate that the area of 
the continuation outlet passage is increasing. 
While ball type valves are preferred, poppet type check valves could be 
utilized. 
Although the invention has been described in terms of specified embodiments 
which are set forth in detail, it should be understood that this is by 
illustration only and that the invention is not necessarily limited 
thereto, since alternative embodiments and operating techniques will 
become apparent to those skilled in the art in view of the disclosure. 
Accordingly, modifications are contemplated which can be made without 
departing from the spirit of the described invention.