Note: Descriptions are shown in the official language in which they were submitted.
.3874~l
This invention relates to a fluid pressure regulator and in
particular to a back pressure regulator for regulating fluid flow.
There are many commercially available back pressure regu-
lators. The problem with most such regulators is the accurate control
of pressure in systems where small, fluctuating variations in pressure
occurs over long or short operating periods. Most prior art back pres-
sure regulators rely on spring-controlled diaphragms which tend to
adversely affect pressure control.
The patent art includes many examples of pressure regulators
including U.S. Patents Nos. 339,757, issued to L. e. Fulton on April 13,
1886; 353,091, issued to W. S. Patterson on November 23, 1886; 697,680,
issued to W. E. Singer on April 15, 1902; 750,752, issued to E. S. Cole
on January 26, 1904i 1,550,445, issued to F. W. Muller on August 18,
1925; 1,745,256, issued to J. C. Groble on January 28, 1930; 1,917,698,
issued to W. W. Carson, Jr. on July 11, 1933; 2,097,829, issued to C. J.
Bassler on November 2, 1937; 2,989,982, issued to S. Soderberg et al on
June 27, 1961; and 2,231,173, issued to C. C. Seger on May 23, 1967.
The object of the present invention is to overcome the above
mentioned problems by providing a back pressure regulator, which permits
the accurate control of fluid flow with relatively little variation in
pressure.
Accordingly, the objects of the present invention are
achieved by providing a fluid pressure regulator which utilizes a
diaphragm of large surface areas, in conjunction with dynamic 0-ring
seals which supply the mechanical friction necessary for effective
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operation. The present invention, therefore, relates to a fluid pres-
sure regulator comprisin~ a casing, a flexible diaphragm dividing said
casing into a control chamber and a flow chamber, a first inlet port in
said casing for introducing a control fluid into said control chamber,
the quantity of control fluid introduced belng based on the predeter-
mined pressure to be controlledi a second inlet port in said casing for
introducing fluid into said casing to bear against the diaphragm on the
control chamber sidei valve means slidably mounted in said flow chamber;
a third inlet port for introducing fluid, the pressure of which is to be
controlled into the flow chamber to bear against said valve means; an
outlet port for receiving fluid from said third inlet port when the
valve is in the open position, whereby any change in the pressure of
fluid flowing through said third inlet port to said outlet port is
detected by said diaphragm, which moves to open or close said valve means
to maintain the pressure constant.
The invention will now be described in greater detail with
reference to the accompanying drawings, which illustrate a preferred
embodiment of the invention, and whereln:
Flgure 1 is a schematic block diagram of a system incor-
: 20 porating a back pressure regulator in accordance with the present
invention; and
Figure 2 is a longitudinal sectional view of the back pres-
sure regulator of Figure 1.
With reference to Figure 1, a back pressure regulator
: 25 generally indicated at 1 is intended for use in a system including a
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pump 2. The pump 2 is connected by a pipe 3, and pipes 4, to tanks 5,
6, and 7 containing a variety of fluids, in this case (i) water, (ii)
water, oil and gas, and (iii) chemicals. A valve 8 is provided in each
pipe 4 for controlling the flow of fluid into the tanks 5, 6, and 7.
Pipes 9 carry fluid from the tanks 5, 6, and 7 through valves 10 to pipe
- 11. The pipe 11 transports the fluid through a sand core 12 and pipe
13 to the pressure regulator 1. The pump 2 is also connected to a pres-
sure gauge 14 by the line 3 and to the pressure regulator 1 by a pipe
15. Fluid from the tank 5, 6, or 7 passing through the pressure regu-
lator 1 is discharged from the regulator through an outlet pipe 16.
; It will be appreciated that while the back pressure regulator
was designed for use in a system of the type described above, the regu-
lator can be used with other systems, the only requirements being a
source of fluid under pressure and a receiver for the fluid passing
. 15 through the back pressure regulator.
Referring to Figure 2, the back pressure regulator 1 includes
a casing 17 defined by upper and lower portions 18 and 19, respectively,
which are held together by bolts 20. A diaphragm 21 is sandwiched
between the upper and lower portions 18 and 19 of the casing dividing
the interior thereof into a control chamber 22 and a flow chamber 23.
; O-rings 24 and 25 provide a fluid-tight seal between the casing portions
18 and 19 and the diaphragm 21.
A gas inlet port 26 is provided in the upper casing portion
18 for introducing control gas into the control chamber 22. Opening and
closing of the port 26 is controlled by a valve defined by a screw 27.
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The pressure in the chamber 22 is measured by means of a gauge 28 con-
nected to the chamber 22 by a port 29. A passage 30 is provided in the
top centre of the upper casing portion 18. A piston 31 is slidably
mounted in the passage 30 for fine control of fluid pressure in the
control chamber 22. An 0-ring 32 provides a fluid-tight seal between
the piston 31 and the cylindrical wall of the chamber 22. A screw 33
extending downwardly through a threaded hole in the top of the upper
casing portion is used to move the piston 31 downwardly. A handle 34
is provided on the top end of the screw 33.
A valve in the flow chamber 23 of the lower casing portion
19 is defined by a disc-shaped body 34 and a valve stem 35 connected to
the bady 34. The valve body 34 is connected to the diaphragm 21 by a
retaining disc 36 mounted above the diaphragm 21 and a screw 37. A
~ backing plate 38 is disposed between the disc 36 and the diaphragm 21.
; lS An 0-ring 39 provides a fluid-tight seal between the bottom of the
diaphragm 21 and the valve body 34, and an 0-ring 40 provides a seal
between an extension 41 of the valve body 34 and the wall of the flow
~ chamber 23.
; The valve body 34 and stem 35 are slidably mounted in the
flow chamber 23, wlth bottom end 42 of the stem 35 closing a passage
between an inlet port 43 and outlet port 44 in the bottom end of the
lower casing portion 19. For production and assembly purposes, the
bottom end of the lower casing portion 19 is defined by a cap 45 separ-
ate from the remainder of the casing portion 19. An 0-ring 46 provides
a seal between the cap 45 and the remainder of the casing. A valve seat
is defined by a rubber insert 47 in the bottom end of the valve stem 35
for closing the inlet port 43. The flow chamber 23 includes a large
diameter portion around the valve stem 35 for receiving cooling medium.
The cooling medium is introduced through an inlet port 4~, and dis-
charge through an outlet port 49.
The ports 50 and 51 are also provided in the casing lower
portion 19 for introducing and withdrawing fluid from beneath the dia-
phragm 21. The port 50 is controlled by a valve defined by a screw 52,
and the port 51 is controlled by a screw 53.
OPERATION
In operation, the back pressure regulator must first be
regulated as to pressure, i.e., prepared for use. With the regulator
oriented so that the port 50 is upward, the port 50 is opened and water
is fed into the port 51 until no more air is discharged through the port
50. The valves 52 and 53 are closed, and the water supply is discon-
nected. The port 26 is connected to a source of an inert gas (nitrogen)
under pressure, and the valve 27 is opened to pressurize the control
chamber 22 to the desired working pressure which registers on the gauge
28. The piston 32 should be one-half the distance between the top and
bottom of the passage 30. When the pressure in the chamber 22 reaches
the desired level, the valve 27 is closed, and the pressure regulator
is ready for use.
The port 51 is connected to the pump 2 and the valve 53 is
opened. The inlet port 43 is connected to the pipe 13 containing fluid
under pressure, and the port 44 is connected to the outlet pipe 16
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which is under atmospheric pressure. If cooling is required, the port
48 is connected to a water supply (not shown), and the port 49 is con-
nected to a discharge pipe (not shown). This enables constant control
of the temperature of the regulator which facilitates accurate flow
control, because the pressure in the chamber 22 is sensitive to temper-
ature variations.
With the pump 2 in operation, the pressure in the system
rises and upward pressure is exerted on the bottom surface of the dia-
phragm 21 and against the valve seat 47. The pressure in the control
chamber 22 increases, but because the gas is compressible, it acts as
, a spring allowing the diaphragm 21 and the valve stem 35 to move up-
wardly, allowing fluid to flow from the port 51 through the flow chamber
and the port 50. At this point, it is quite likely that the flow pres-
sure through the bottom of flow chamber 23 is not the desired pressure.
; 15 Fine adjustment can be effected by turning the handle 34 to move the
piston 31 upwardly or downwardly to change the pressure in the control
chamber 22, and thus the pressure required to move the diaphragm 21 and
the valve stem 35. A large reduction of the gas pressure in the chamber
22 can be effected by opening the port 26 to the atmosphere. Before
depressurizing the system, all of the valves 27, 52 and 53 must be
closed to avoid an unnecessary pressure drop. If depressurizing is not
done in the proper manner, a mechanical failure of the system may result.
Thus, there has been described a back pressure regulator
which is capable of accurately controlling pressure by means of a gas
pressurized diaphragm and a control chamber. The system described here-
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inbefore is capable of quick response without erratic operation.
Because the pressure of a confined gas varies inversely with volume, a
relatively small change in the volume of the control chamber 22 results
in a large change in pressure. Thus, any tendency of the diaphragm 21
to move is opposed by the pressure in the chamber 22. The surface area
of the diaphragm 21 is approximately 230 times that of the valve seat
~ 47 acted on by fluid, the pressure of which is being controlled.
-~ The pressure regulator disclosed herein avoids the in-
conveniences of a metal spring. By eliminating the possibility of
corrosive substances passing through the control portion of the regu-
lator, the possibility of corrosion damage to the regulator is minimized.
Further modifications and alternative embodiments of the
invention will be apparent to those skilled in the art in view of the
foregoing description. Accordingly, this description is to be construed
as illustrative only and is for the purpose of teaching those skilled
in the art, the manner of carrying out the invention. It is further
understood that the form of the invention herewith shown and described
is to be taken as the presently preferred embodiment. Various changes
may be made in the shape, size and general arrangement of components,
for example, equivalent elements may be substituted for those illustrated
and described herein, parts may be used independently of the use of
other features, all as will be apparent to one skilled in the art after
having the benefits of the description of the invention.
