AU722683B2

AU722683B2 - Pressure equalization valve

Info

Publication number: AU722683B2
Application number: AU62019/96A
Authority: AU
Inventors: Yeshwant K Bhide
Original assignee: Babcock and Wilcox Co
Current assignee: Diamond Power International Inc
Priority date: 1995-08-09
Filing date: 1996-08-09
Publication date: 2000-08-10
Anticipated expiration: 2016-08-09
Also published as: CN1070597C; CA2182843C; CN1152682A; KR100413121B1; ZA966759B; CA2182843A1; KR970011526A; TW365638B; AU6201996A

Description

P/00/011 Regulation 3.2

AUSTRALIA

Patents Act 1990

SUBSTITUTE

COMPLETE SPECIFICATION STANDARD PATENT Invention Title: PRESSURE EQUALIZATION VALVE q

S

a. The following statement is a full description of this invention, including the best method of performing it known to us: GH REF: P07940-KK:RPW:RK fI1 1 l BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to devices useful for equalizing fluid pressures. More particularly, the present invention relates to pressure equalization valves useful for equalizing fluid pressures between plural fluid sources.

Description of the Invention's Background As shown in Fig. i, which is a diagram of a prior art material handling system, an airlock, such as an airlock 1, is 1 a device used for the transfer, by gravity, of fly ash or other dry, free-flowing granular solids from one pressure zone to another. For example, in the system of Fig. 1, granular solids are collected in an overhead hopper 2 and are dropped into the airlock 1 in controlled volumes through operation of 1 a pneumatically-operated valve 3. Each controlled volume of granular solids is then dropped, by means of another pneumatically-operated valve 4, into a conveying pipe carrying a supply of pressurized conveying fluid, such as air.

The air in the conveying pipe is generally compressed up to psi, but may be compressed up to 25 psi.

Because the pressurized conveying fluid is normally at a much higher pressure than the near-atmospheric pressure inside the airlock 1, the pressure differential would slow down the movement of solids from the airlock 1 into the pipe 5 if it were not equalized. Accordingly, prior art material handling systems such as that shown in Fig. 1 often include a pressure equalization valve 6.

With reference to Fig. 1 and Figs. 2-3, which illustrate two prior art equalization valves equalization valves 6" each include a port respectively, in fluid -1Acommunication with an airlock 1 via a fluid line 7, a port 8', respectively, in fluid communication with a conveying pipe at point 5a via a fluid line 8, and a port 9", respectively, in fluid communication with a hopper 2 via a fluid line 9. Each equalization valve 6" also includes valve gates 10', 10", respectively, operable by an actuator 11', 11", respectively, for alternately sealing the ports 8', 9' and respectively.

An equalization valve 6, 6" normally operates as follows. Before a volume of granular solids is dropped from 1 the hopper 2 into the airlock 1, the valves 3, 4 are in a closed position. The actuator 11', 11", respectively, is in a position such that the port respectively, is sealed and the port 9" is open. The hopper 2 and the airlock 1 are thus in fluid communication, and the pressure of the air in the hopper 2 above the solids and the pressure of the air in the airlock 1 are nearly equal and nearly at atmospheric pressure. The volume of granular solids is then dropped into the airlock 1 by opening and timed closing of the valve 3, and the actuator 11', 11", respectively, is then operated so that the port respectively, is open and the port 9", 2 0 respectively, is sealed. The conveying pipe 5 is thus in fluid communication with the airlock 1 at point 5a, and the pressure of the air in the airlock 1 thus nearly equalizes to the much higher pressure of the air in the conveying pipe 5 at point Sa. The pressures normally do not completely equalize 25 because of the pressure drops inherent in the system. The entire pressure equalization process usually takes no more than 5-15 seconds, depending on the volume of the airlock 1.

The solids are then dropped into the conveying pipe 5 at point 5c by the opening of the valve 4, and are carried away through the pipe 5. It should be noted that the pressure of 2 1 the air at the point Sc is much lower than at the point (and thus in the airlock because an orifice is interposed in the pipe 5 at point 5b intermediate points Sa and 5c. The resultant pressure drop between the airlock and point Sc encourages the flow of solids into the pipe 5. When the valve 4 is closed, some residual solids generally remain in the airlock 1. The actuator respectively, is then operated to seal the port respectively, and to open the port respectively, such that the airlock 1 and the hopper 2 are again in fluid communication and the pressure of the air in the airlock 1 can equalize with the nearatmospheric pressure of the air in the hopper 2. During each pressure equalization process, the velocity of the air passing through the equalization valve 6" can reach almost sonic speeds, due to the extreme pressure differential between the air in the conveying pipe 5 and the airlock 1, and then the airlock 1 and the hopper 2. In addition, during the pressure equalization process between the airlock 1 and the hopper 2, the air flowing through the equalization valve 6" normally entrains a significant amount of loose granular solids from the airlock 1, which air/solids mixture is normally very 20 abrasive when flowing at high speeds.

Prior art pressure equalization valves 6" have significant disadvantages. First, such valves 6" tend to have very rapid wear rates, especially with respect to the valve ports the valve gates 10', 10" and the actuators 11', 11", respectively, which are cyclically subjected to blasts of granular articulates entrained in air streams moving at near-sonic speeds. It has been estimated that wear rates on such parts are proportional to v 3 where v is equal to the velocity of the air-solids mixture. For some prior art equalization valves 6, it is not uncommon for the valves 6 to 3 require replacement within three months of being put into service.

Further, pressure equalization valves such as the valves 6" are designed such that, when an actuator 11', 11", respectively, is operated to move between port sealing positions, there is a period of time where both the port 9' and the port respectively, are open, allowing pressure equalization between the airlock i, the hopper 2 and the conveying pipe 5 all at the same time. In systems that are vacuum-operated, as opposed to the pressurized system shown in Fig. 1, this transient three-way equalization has been found to result in the suction of granular solids into the vacuum pumps, and thus increased maintenance of such pumps In view of the above, it would be advantageous of preferred embodiments of the present invention to provide an improved pressure equalization valve.

It would be advantageous of preferred embodiments of the present invention to provide a pressure equalization valve that wears at a relatively slow rate.

It would be advantageous of preferred embodiments of the present invention to provide a pressure 25 equalization valve that restrains unintended transient o0*:t* equalization of fluid sources.

Also, it would be advantageous of preferred embodiments of the present invention to provide a pressure equalization valve having internal components that are relatively wear resistant.

Again, it would be advantageous of preferred embodiments of the present invention to provide a pressure equalization valve having internal components that are relatively easy to service and replace.

00 S:07940-KK 4 SUMMARY OF THE INVENTION The present invention provides a pressure equalization valve for alternatingly equalizing pressures between a first fluid source and at least two second fluid sources, comprising: a valve body including a first port in fluid communication with the first fluid source, said first port having a central axis, said valve body further including at least two second ports, each in fluid communication with the respective second fluid source, each said second port having a central axis wherein said central axis of at least one said second port forms an acute angle with said central 15 axis of said first port; a valve gate movable between a first equalizing position wherein said valve gate allows fluid flow through Soe.. one of said second ports and restrains fluid flow through another of said second ports to substantially equalize the fluid pressure between the first fluid source and one of the second fluid sources, and a second equalizing position, wherein said valve gate allows fluid flow through said another of said second ports and restrains fluid flow through said one of said second ports to equalize 25 substantially the fluid pressure between the first fluid source and another of the second fluid sources; a valve seat at each of said second ports, said valve seat having a contact surface and wherein said valve gate has a contact surface adapted to slidably confront said contact surface of said valve seat, said valve gate and said valve seat being fabricated from Ni-Hard material; and \\GHSYDNT1\uers\Speci\200 299\250 299\29178.doc a chamber in said valve body between said first port and said second ports, wherein said chamber has a predetermined volume such that the velocity of fluid flowing between said first port and at least one of said second ports is substantially reduced.

The invention in another aspect provides a pressure equalization valve for alternatingly equalizing pressures between a first fluid source and at least two second fluid sources, comprising: a valve body including a first port in fluid communication with the first fluid source, said first port having a central axis, said valve body further including at least two second ports, each in fluid communication with the respective second fluid source, each said second port 15 having a central axis wherein said central axis of at least one said second port forms an acute angle with said central oo axis of said first port; a valve gate movable between a first equalizing position wherein said Valve gate allows fluid flow through one of said second ports and restrains fluid flow through another of said second ports to substantially equalize the fluid pressure between the first fluid source and one of the second fluid sources, and a second equalizing position, wherein said valve gate allows fluid flow through said 25 another of said second ports and restrains fluid flow o through said one of said second ports to equalize substantially the fluid pressure between the first fluid source and another of the second fluid sources, said valve gate being further movable to an intermediate position intermediate said first and second equalizing positions, wherein said valve gate restrains fluid flow through both said second ports; \\GHSYDNT \users\Speci\200 299\250 299\29178dc 09/06 '00 FRI 14:58 FAX 61 2 9957 3582 GRIFFITH HACK 444 PO EXAMINERS 0~j04 6A a valve seat at each of said second ports, said valve seat having a contact surface and wherein said valve gate has a contact surface adapted to slidab]-y confront said contact surf ace of said valve seat, Said valve gate anTd said valve seat being fabricated from Ni-Hard material; and a chamber in said -valve hougsing between said f irst port and said second ports, wherein as measured in planes perpendicular to said central axis of said first port, a largest cross-sectional area of said chamber is at least ten times larger than a smallest cross-sectional area of sadfirst port.

*The present invention in a further aspect provides a removable cover plate assembly for a pressure equalization 15 valve having a valve body having a first port therein :having a first central axis and being in fluid communication with a first fluid source, said removable cover plate assembly comprising: a cover plate removably attachable to said valve body, said cover plate having at least two second ports each constructed for fluid communication with a respective ****second fluid source, each said second port having a central axis wherein said central axis of at least one said second port forms an acute angle with respect to the central axis of said first port when said cover plate is attached to said valve body; a valve seat attached to said cover plate adjacent to each said second port, said valve seat having a contact surface; 09/06 '00 FRI 14:58 [TX/RX NO 92761 6B a valve gate removably attached to said cover plate and being constructed for sliding confrontation with said valve seat to permit fluid flow through one of said second ports and restrain fluid flow through another of said second ports to equalize substantially fluid pressure between the first fluid source and one of said second fluid sources and a second equalizing position wherein said valve gate restrains fluid through said one of said second ports and permits fluid flow through said other of said second ports, said valve gate having a contact surface adapted to slidably confront said contact surface of said valve seat, said valve gate and said valve seat being fabricated from Ni-Hard material; and 15 a rotary actuator attached to said cover plate and said valve gate for selectively moving said valve gate between said first and second equalizing positions.

BRIEF DESCRIPTION OF THE DRAWINGS The preferred embodiments of the present invention will be described in greater detail with reference to the accompanying drawings, wherein like members like reference numerals and wherein: Fig. 1 is a diagram of a prior art material handling 25 system; Fig. 2 is a cross sectional view of a prior art pressure equalization valve; Fig. 3 is a cross sectional view of another prior art pressure equalization valve; \\GHSYDNT1\user\Seci\200 299\250 299\29178.doc Fig. 4 is a front elevational view of a first embodiment of a pressure equalization valve of the present invention; Fig. 5 is a cross sectional view along line V-V of Fig. 4; Fig. 6 is a cross sectional view along line VI-VI of Fig. 4; Fig. 7 is a cross sectional view along line VII-VII of Fig. 6; and Fig. 8 is a view similar to Fig. 6 of a second embodiment of the pressure equalization valve of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT With reference to Figs. 4-7, a pressure equalization valve 16 in accordance with a first embodiment of the present g* i:ASpeci2OO 299\250 2999178.doc invention includes a valve body 18, a first port 22 in fluid communication with a first fluid source, such as air within the airlock 1 in the material handling system of Fig. i, and a pair of second ports 24, 26 in fluid communication with a pair of second fluid sources, such as air within the hopper 2 and pressurized air within the conveying pipe 5, respectively. As shown in Fig. 5, the first port 22 is located along a first wall 28 of the valve body 18, and the second ports 24, 26 are located along a second wall 30 of the valve body 18, which second wall 30 is directly opposite the first wall 28.

Moreover, a central axis A of the first port 22 and a central axis B of the second port 24 lie along portions of the same line (see Figs. 5 and and the second port 26 is angled acutely by about 10-15 degrees relative to that line, such that the central axis C of the second port 26 lies along a line that is acutely angled relative to the axis A by about 10-15 degrees and that extends into the first port 26 (see Fig. The significance of these features will be explained further hereinbelow.

The valve 16 also includes a piston 32 slidingly "connected to a cylinder (not shown) and pivotally connected to a link 34 by a pin 36. The link 34 is pivotally connected to a link 38 by a pin 40, and the link 38 is fixed to a pivot pin 42 to restrain rotation of the link 38 relative to the pivot pin 42. Within the valve body 18, a valve actuator 44 is fixed to the pivot pin 42 such that rotation of thevalve *:actuator 44 relative to the pivot pin 42 is also restrained.

As can be seen in Figs. 6 and 7, the valve actuator 44 is roughly triangular in shape, and includes a pair of hollow cylindrical extensions 46 therein. An elongated ovoid valve gate 50 preferably made of ground Ni-hard and having a pair of solid cylindrical extensions 52 thereon is provided such that 7 the solid extensions 52 are slidingly mounted within the hollow extensions 46. Each of the hollow extensions 46 includes a spring, such as a coil spring 56, therein to spring bias the valve gate 50 away from the valve actuator 44. The valve body 18 further includes a valve seat plate 58 preferably made of ground Ni-hard and attached on an inner surface of the second wall 30. The valve seat plate 58 has a pair of openings 60, 62 therein to form coplanar valve seats 64, 66, respectively, at the two second ports 24, 26. Because the valve gate 50 is spring biased away from the valve actuator 44, it is also spring biased against the valve seat plate 58. As will be discussed further hereinbelow, the valve gate 50 acts as means to control the flow of fluid through the second ports 24, 26 alternately.

All materials of which the valve 16 is constructed preferably have a 750 degree Fahrenheit temperature rating.

The valve body 18 further includes a chamber intermediate the first and second walls 28, 30, respectively, and thus between the first port 22 and the second ports 24, 26, respectively. The chamber 70 is very large relative to the ports 22, 24, 26. Thus, when measured in planes 2 0 perpendicular to the central axis A of the first port 22, such as planes containing the lines D and E shown in Fig. 6, the largest cross sectional area of the chamber 70 is ooo substantially larger than the smallest cross sectional area of the first port 22, as will be discussed further hereinbelow.

o: 25 With reference to Figs. 1 and 4-7, the structure and operation of the first embodiment of the pressure equalization valve 16 will now be explained. As discussed above, the first "port 22 is normally in fluid communication with a first fluid source, such as the air within the airlock 1 via the fluid line 7, one second port 24 is normally in fluid communication 8 with one second fluid source, such as the hopper 2 via the fluid line 9, and another second port 26 is normally in fluid communication with another second fluid source, such as the conveying pipe 5 via the fluid line 8. In a first equalizing position, the valve actuator 44 and the valve gate 50 are rotated roughly 80-85 degrees clockwise from the position shown in Fig. 7. The valve gate 50 is spring biased against and extends across the valve seat 66 to close the opening 62, and thus fluid flow through the second port 26 is restrained and fluid flow through the second port 24 is allowed by the valve gate 50. The valve gate 50 would be in the first equalizing position if the valve 16 were being used in the system of Fig. 1 and a volume of granular solids was waiting to be dropped from the hopper 2 into the airlock 1i. The hopper 2 and the airlock 1 would thus be in fluid communication, and the pressure of the air in the hopper 2 above the solids and the pressure of the air in the airlock 1 would be nearly equal and nearly at atmospheric pressure. The volume of granular solids could then be dropped into the airlock 1 by means of the valve 3.

2 When the piston 32 is controlled to retract and to pull the links 34, 38 clockwise in Fig. 4 and thus to rotate the pivot pin 42 clockwise in Fig. 4, rotation of the pivot pin 42 S: (counterclockwise in Fig. 7) causes the valve actuator 44 and thus the valve gate 50 to rotate counterclockwise in Fig. 7 with the pivot pin 42. The valve gate 50 thus moves from the 25 "9 first equalizing position to an intermediate position, wherein the valve gate 50 is spring biased against and extends across both valve seats 64, 66 to close both openings 60, 62 and restrain fluid flow through both second ports 24, 26. From this point in its movement, the valve gate 50 remains spring biased against the valve seat 64, but continued movement 9 causes the valve gate 50 to slide across the opening 66 until the valve gate 50 is in a second equalizing position wherein the valve gate 50 is spring biased against and extends across only the valve seat 64 to close only the opening 60. In the second equalizing position, shown in Fig. 7, the valve seat thus restrains fluid flow through the second port 24 and allows fluid flow through the second port 26 to equalize substantially the fluid pressure between the first fluid source and the other second fluid source. If the valve 16 were being used in the system of Fig. 1, the conveying pipe would thus be in fluid communication with the airlock 1i, and the pressure of the air in the airlock 1 would thus substantially equalize to the much higher pressure of the air in the conveying pipe 5. The pressures normally would not completely equalize because of the pressure drops inherent in the system. The solids would then be dropped into the conveying pipe 5 by means of the valve 4 and carried away through the pipe When the piston 32 and thus the valve actuator 44 are operated in reverse, the valve gate 50 moves back through the intermediate position to the first equalizing position, wherein fluid flow through the second port 26 is restrained and fluid flow through the second port 24 is allowed, to equalize substantially the fluid pressure between the first fluid source and the one second fluid source. If the valve 16 were being used with the system of Fig. 1, the airlock 1 and 25 the hopper 2 would again be in fluid communication and the pressure of the air in the airlock 1 would substantially equalize with the near-atmospheric pressure of the air in the hopper 2.

During each pressure equalization process, the velocity of the fluid entering the chamber 70 in the valve body 18, for 10 example from the first port 22, may achieve almost sonic speeds, due to the extreme pressure differentials that it is expected would exist in normal use between the first and second fluid sources, respectively. However, because, as measured in planes perpendicular to the central axis A of the first port 22, the largest cross sectional area of the chamber is substantially larger than the smallest cross sectional area of the first port 22, the velocity of a fluid flowing from the first port 22 to a second port, such as the second port 24, will be substantially reduced.

This result is dictated by the mass flow rate equation, which states that for a fluid flowing through an enclosed space, the cross sectional area of the space multiplied by the velocity and density of the fluid equals a constant. Thus, if the cross sectional area of the space increases, the fluid velocity should decrease proportionally, assuming the density remains constant. When the fluid flowing through the valve 16 consists of particulate matter entrained in a gas, it has been found that the particulate matter generally remains entrained in the gas while traveling through the chamber 70. Thus the density of the fluid remains fairly constant, although the density of the fluid does drop a fairly insignificant amount due to normal pressure losses in the fluid lines and the valve oo: 16. Accordingly, the increased cross sectional area of the chamber 70 appears to produce a substantial reduction of the velocity of such a fluid flowing through the chamber 70. In 25 actual tests, a valve including a chamber having a largest cross sectional area of roughly 14 times the smallest cross sectional area of a first port has been found to have substantially improved wear rates over prior art pressure equalization valves. It is estimated that the velocity of the fluid flowing within such valve is reduced by about 14 times 11 from a first port to a second port. As stated above it is believed that the wear rate varies proportionally with v 2 and it is thus estimated that the wear rate on the valve actuator and the valve gate of such valve may be reduced by as much as 2,744 times. Because of the exponential relation between velocity and wear rate, it is believed that a chamber having a largest cross sectional area of 10 times the smallest cross sectional area of the first port 22 would substantially reduce the velocity of fluid flowing through the chamber, and would produce advantageous wear rate results. In such a valve, it is estimated that the fluid velocity would be reduced about 10 times, to produce a wear rate reduction on the order of 103.

In addition, it is believed that the positioning of the second ports 24, 26 on the second wall 30 opposite the first port 22, such that the central axes B, C of the second ports 24, 26 either lie on the central axis A of the first port 22, or are acutely angled within 10-15 degrees relative thereto and thus lie on lines that extend into the first port 22, helps to reduce the wear rate of the internal valve parts.

Because of this positioning of the second ports 24, 26, a Sfluid flowing from the first port 22 to a second port 24 or 26, or from a second port 24 or 26 to the first port 22, follows a relatively streamlined flow path through the valve 16, thus subjecting the internal valve parts to relatively less direct blasting from granular solids entrained in the 25 2 fluid. In addition, because the valve seat plate 58 and the i valve gate 50 are made of ground Ni-hard, they are relatively wear resistant.

It should also be appreciated that because the valve gate reaches the intermediate position wherein fluid flow through both of the second ports 24, 26 is restrained each 12 time that it moves between the first and second equalizing positions, the valve 16 restrains transient cross equalization between the second fluid sources. When the valve 16 is used with a vacuum system, this feature is useful to restrain the unintended flow of granular solids entrained in a fluid into a vacuum pump, thereby reducing wear on and maintenance of the pump.

A further advantage of the present invention arises from the construction of the valve 16. Specifically, as can be seen in Figs. 4 and 6, the second ports 24, 26, the links 34, 38, the pivot pin 42, the valve actuator 44 and the valve gate are all mounted, directly or indirectly, to the second wall of the valve body 18, and the second wall 30 is mounted to the remainder of the valve body 18 by six bolts 31. Thus, the valve actuator 44 and the valve gate 50 may be easily serviced or replaced merely by disconnecting the piston 32 from the pin 36, unscrewing the bolts 31 and removing the second wall With reference to Fig. 8, a second embodiment of the pressure equalization valve 116 of the present invention is illustrated, wherein parts of the valve 116 similar to parts of the valve 16 are numbered similarly, with the addition of S 100 to the numbers. The valve 116 is structured and functions identically to the valve 16, with one exception.

Specifically, the valve 116 includes an elongated chamber 170, and a valve body 118 of the valve 116 includes an elongated removable door 180, to allow on-site maintenance of the valve 25 r 116. The removable door 180 is especially useful in on-site emergency situations.

It should be appreciated that, as used throughout the specification and claims, the term "fluid" is used to refer broadly to any type of fluid including a gas, a gas/solid mixture, a gas/liquid mixture, or a liquid. In addition, the 13 term "fluid source" as used herein is used broadly to refer to any mass of fluid, including a mass under very high or very low pressure, such as would exist in a vacuum system. It should also be appreciated that, while the ports 22, 24, 26 are illustrated and described as being one piece with the valve body 18, they may be separate pieces attached to the valve body 18, or may consist of the terminal ends of fluid lines attached to the valve body 18. Also, although the valve seat plate 58 and thus the valve seats 64, 66 are illustrated and described herein as being separate from the valve body, the valve seat plate 56 may be removed from the valve 16 such that the valve seats 64, 66 would consist of the terminal ends of the ports 24, 26.

In such an embodiment, the ports 24, 26 preferably would be formed such that the valve seats 24, 26 were coplanar. Further, although the operating means for operating the valve actuator 44 to move the valve gate is shown as including a piston 32, links 34, 38 and pivot pin 42, other operating means, such as a rotary type of actuator, could be used and the advantages of the present invention obtained thereby.

The principles, a preferred embodiment and the t mode of operation of the present invention have been 0.0000 0 25 described in the foregoing specification. However, the invention which is intended to be protected is not to Sbe construed as limited to the particular embodiment disclosed. The embodiment is therefore to be regarded as illustrative rather than restrictive. Variations 30 and changes may be made by others without departing from the spirit of the present invention. Accordingly, o• .it is expressly intended that all such equivalents, t variations and changes which fall within the spirit and scope of the present invention be embraced thereby.

cO S:07940-KK 14

Claims

1. A pressure equalization valve for alternatingly equalizing pressures between a first fluid source and at least two second fluid sources, comprising: a valve body including a first port in fluid communication with the first fluid source, said first port having a central axis, said valve body further including at least two second ports, each in fluid communication with the respective second fluid source, each said second port having a central axis wherein said central axis of at least one said second port forms an acute angle with said central axis of said first port; 15 a valve gate movable between a first equalizing position wherein said valve gate allows fluid flow through one of said second ports and restrains fluid flow through S. another of said second ports to substantially equalize the fluid pressure between the first fluid source and one of the second fluid sources, and a second equalizing position, wherein said valve gate allows fluid flow through said another of said second ports and restrains fluid flow through said one of said second ports to equalize Ssubstantially the fluid pressure between the first fluid 25 source and another of the second fluid sources; S"a valve seat at each of said second ports, said valve seat having a contact surface and wherein said valve gate has a contact surface adapted to slidably confront said contact surface of said valve seat, said valve gate and said valve seat being fabricated from Ni-Hard material; and a chamber in said valve body between said first port and said second ports, wherein said chamber has a predetermined volume such that the velocity of fluid fflowing between said first port and at least one of said econd ports is substantially reduced. \GHSYDNT1\users\Speci\200 299\250 299\29178.dOc 09/06 '00 FRI 14:58 FAX 61 2 9957 3582 GIFT AK4~ 0EAIES Ij0 GRIFFITH HACK 444 PO EXAMINERS Z005 16

2. A pressure equalization valve as claimed in claim 1 wherein as measured in planes peirpendicular to the central axis of said first port, a largest cross-sectional area of said chamber is at least ten times larger than a smallest cross-secti.onal area of said first port.

3. A pressure equalization valve as claimed in any one of the preceding claims wherein said valve gate is further movable to an intermediate position intermediate said f irst and second equalizing positions, wherein said valve gate restrains fluid flow through both said second ports-

4. A pressure equalization valve as claimed in any one of the preceding claims wherein said valve gate is attached to a rotary actuator for moving said valve gate between said first and second equalizing positions.

A pressure equalization valve as claimed in any one of the preceding claims further comprising a cover plate removably attached to said valve body, said cover plate having said second ports extending therethrough and said valve seat attached thereto and surrounding each said second port to sealingly confront said valve gate as said valve gate is moved between said first and second equalizing positions.

6. A pressure equalization valve as claimed in claim wherein said rotary actuator is attached to said cover plate and has a rotatable actuator pin extending into said valve body and wherein said pressure equalization valve further- comprises a -valve gate arm attached to said actuator pin and said valve gate.

7. A pressure equalization valve as claimed in claim 6, wherein said -valve gate is biased away from said valve gate arm into sealing contact with said valve seat. 0!\flpei\200 29.9\25D 299\29175,49a 09/06 '00 FRI 14:58 [TX/RX NO 92761

8. A pressure equalization valve as claimed in any one of the preceding claims wherein said central axis of at least one other said second port is coaxially aligned with said central axis of said first port.

9. A pressure equalization valve for alternatingly equalizing pressures between a first fluid source and at least two second fluid sources, comprising: a valve body including a first port in fluid communication with the first fluid source, said first port having a central axis, said valve body further including at least two second ports, each in fluid communication with the respective second fluid source, each said second port 15 having a central axis wherein said central axis of at least one said second port forms an acute angle with said central axis of said first port; :i a valve gate movable between a first equalizing position wherein said valve gate allows fluid flow through one of said second ports and restrains fluid flow through another of said second ports to substantially equalize the fluid pressure between the first fluid source and one of the second fluid sources, and a second equalizing position, wherein said valve gate allows fluid flow through said 25 another of said second ports and restrains fluid flow S. through said one of said second ports to equalize substantially the fluid pressure between the first fluid source and another of the second fluid sources, said valve gate being further movable to an intermediate position intermediate said first and second equalizing positions, wherein said valve gate restrains fluid flow through both said second ports; a valve seat at each of said second ports, said valve seat having a contact surface and wherein said valve gate Shas a contact surface adapted to slidably confront said \\GHSYDNT1\users\Speci\200 299\250 299\29178.dOc contact surface of said valve seat, said valve gate and said valve seat being fabricated from Ni-Hard material; and a chamber in said valve housing between said first port and said second ports, wherein as measured in planes perpendicular to said central axis of said first port, a largest cross-sectional area of said chamber is at least ten times larger than a smallest cross-sectional area of said first port.

10. A pressure equalization valve as claimed in claim 9 wherein said valve gate is attached to a rotary actuator for moving said valve gate between said first and second equalizing positions. 15

11. A pressure equalization valve as claimed in claim 9 or 10 further comprising a cover plate removably attached to said valve body, said cover plate having said second ports extending therethrough and said valve seat attached thereto and surrounding each said second port to sealingly confront said valve gate as said valve gate is moved between said first and second equalizing positions. •go•

12. A pressure equalization valve as claimed in claim 11 wherein the rotary actuator is attached to said cover 25 plate, said rotary actuator having a rotatable actuator pin extending into said valve body and the valve further comprises a valve gate arm attached to said actuator pin and said valve gate.

13. A pressure equalization valve as claimed in claim 12, wherein said valve gate is biased away from said valve gate arm into sealing contact with said valve seat.

14. A pressure equalization valve as claimed in claim 9 or 10 wherein said central axis of at least one other "said 299\250 299\29178.doc 09/06 '00 FRI 14:59 FAX 61 2 9957 3582GRFIH AC P EX IESIj00 GRIFFITH RACK 444 PO EXAMINERS R006 19 second port is coaxially aligned with said central axis of said first port.

A removable cover plate assembly for a pressure equalization valve having a valve body having a first port therein having a first central axis and being in fluid communication with a first fluid source, said removable cover plate assembly comprising: a cover plate removably attachable to said valve body, said cover plate having at least two second ports each constructed for fluid communication with a respective second fluid source, each said second port having a central axis wherein said central axis of at least one said second port forms an acute angle with respect to the central axis of said first port when said cover plate is attached to said valve body; a valve seat attached to said cover plate adjacent to each said second port, said valve seat having a contact surface; :20 a valve gate removably attached to said cover plate and being constructed for sliding confrontation with said valve seat to permit fluid flow through one of said second ports and restrain fluid flow through another of said second ports to equalize substanitially fluid pressure between the first fluid source and one of said second fluid sources and a second equalizing position wherein said valve gate restrains fluid through said one of said second ports and permits fluid flow through said other of said second ports, said valve gate having a contact surface adapted to slidably confront said contact surface of said valve seat, said valve gate and said valve seat being fabricated from Ni-Hard material; and a rotary actuator attached to said cover plate and said valve gate for selectively moving said valve gate between said first and second equalizing positions- a!N5PeCi%300 29;0- 299\29078.4c. 09/06 '00 FRI 14:58 [TX/RX NO 9276] 09/06 '00 FRI 14: 59 FAX 61 2 9957 3582 GRIFFITH HACK 4-+4 PO EXAMINERS iZj007

16. A removable cover plate assem~bly as claimed in claim wherein said central axis of at least one other said second port is coaxially aligned with said central axis of said first port when said cover plate assembly is attached to said valve body.

17. A pressure equalization valve substantially as herein described with reference to figures 4-8 of the accompanying drawings Oe 09** S S S 5- S S. S S OS'S S 055b S S 5~55 S OS S 0500 S S *OO. SOS. 0* *5 *55* S Dated this 7th day of June 2000 THE BABCOCK WILCOX COMPANY By their Patent Attorneys GRIFFITH HACK j79.i20- 799\250 299\Z18.do- 09/06 '00 FRI 14:58 ITX/RX NO 9276]