Abstract:
An on-off valve that can operate between an open position and a closed position. The on-off valve has a valve body with a cylindrical valve cavity, an inlet, an outlet, and in an open position the inlet is in communication with the outlet. A cylindrical valve cartridge is sealably mounted within a chamber of the valve cavity and has a central cavity facing the valve cavity and a bore forming communication with an atmosphere external to the valve cartridge. A pin extension is movably mounted within the bore. A pin bushing and a pin seal are mounted within the central cavity, and an actuating pin is movably mounted at least partially within the central cavity. A valve poppet is slidably mounted within the valve cavity. In a closed position a first end portion of the valve poppet closes the first outlet, and in an open position the first end portion opens the first outlet. A bias element is mounted to exert a bias force to and urge the valve poppet against the valve cartridge. An actuator is mounted with respect to the valve body and operates the actuating pin between the open position and the closed position of the on-off valve.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    On-off valves are important components to all fluid power systems. There are many types of known valves to choose when the fluid system pressure is low because there are many suitable valving mechanisms. When fluid pressure is very high, the selection of suitable valving mechanism is drastically reduced because of the stressful conditions imposed on the valving elements. For example, the water pressure involved in known industrial water jetting processes is frequently greater than 20,000 pounds per square inch (psi), and at such pressures the valving elements responsible for opening and closing a valve outlet port are under very high fluid-induced stresses and their selection is limited in terms of shape, size, design, material of construction, and operation. The selection of suitable known valves is limited to stem valves, needle valves, poppet valves, and ball valves. The conventional names of these valves denote the key valving element responsible for opening and closing the valve port. These valving elements are typically operated by an external force such as a hand force through a push or pull, or in turning, or a push/pull force provided by a pneumatic/hydraulic actuator. Thus, a typical on-off valve has valving elements partly situated inside a valve cavity and partly outside the valve cavity. The part situated inside the valve cavity is exposed to all detrimental conditions involved in controlling the flow of a high-pressure fluid. 
         [0002]    One of the detrimental elements in high-pressure valving is the erosion of fluid on critical valving parts, namely the valve needle or stem and the mating valve port seat. A hand-operated needle valve generally has a threaded arrangement and a valve needle is moved slowly in and out of a tapered valve port so that the fluid starts to flow as soon as the seal is broken. This early flow is extremely erosive despite its low flow rate and can damage the valve needle or the valve seat, or both. Once damaged, the hand force required for closing the valve is increased, thus exacerbating the damage. It is known that a new needle valve can be damaged and need replacement parts after only one operation. It is also known that a slow valve should not be used for adjusting the flow rate of a high-pressure fluid, such as water that has relatively poor lubricity. It is extremely desirable to employ a fast on-off action with a suitable valving mechanism to open and close an outlet port to minimize the possibility of fluid erosion. If adjustment of flow rate is desired, it should be done by controlling the flow with multiple orifices positioned downstream from the valve. Also, the multiple orifices should open and close with fast action. These orifices are either opened or closed, and not in a position between. 
         [0003]    To provide the desired motion in a valving element inside a valve cavity, a suitable arrangement in the external valving elements is required to handle the available force. The required external force is a function of the fluid pressure and the design of the valving element exposed to the fluid. For example, a straight valve stem of 0.250 inches in diameter is pushed out by the fluid with a force of 981 pounds at a pressure of 20,000 psi, 1963 pounds at 40,000 psi, and 3928 pounds at 80,000 psi. These are normal static pressures applied in known water jetting processes. The magnitude of the force exerted on the valve stem presents many problems in designing a suitable on-off valve. First, the valve stem must be strong enough and well supported to withstand the fluid induced forces. The valve stem must be properly sealed to prevent the fluid leakage. The provided external force must be strong and fast to move the valve stem and to seal the valve port properly and continuously. The impact between the valve stem and the valve seat should be kept low to avoid impact damage on the sealing surface. The opening of the valve outlet must also be fast to avoid erosion. All these conditions inside a valve cavity must be met in designing a suitable valve. 
         [0004]    Another concern in valve design is the external force needed to operate the valving elements. The 981 pounds force required for operating a 0.250-inch-diameter valve stem is considered relatively high and beyond forces that can be provided by a human body. The required forces are considered high even with pneumatic actuators. The necessary size of the actuator and an air pressure needed to move the air piston should be considered. A bulky and heavy air actuator can present problems in many water jetting applications. As a result, efforts are directed to minimizing the diameter of the valve stem involved. Consequently, the diameter of the air piston is reduced and the required air pressure is also reduced. Unfortunately, reducing the diameter of the valve stem requires a corresponding reduction in the diameter of the valve port because the mating surface between the valve stem and a corresponding valve seat is typically in a coned arrangement. Thus, the outlet port is sufficiently smaller than the diameter of the valve stem. As a result, the flow capability of a high-pressure valve is often limited, unless the valve size is of no concern. 
         [0005]    Referring to  FIG. 1 , a known basic design of a fast acting on-off valve commonly employed in a waterjet factory cutting processes is quite simple. The known design employs a spring-loaded air piston to impose a valve-closing force on a small valve stem which has a flat end outside the valve cavity and a tapered end inside the valve cavity, to mate with a concave valve outlet. The valve is normally closed by the spring force. To open the valve, compressed air of specified pressure enters into the actuator and to a side of an air piston opposite to the compression spring. The compressed air exerts a lifting force on the piston and moves it up against the compression spring, thus relieving the force on the valve stem. The pressurized water inside the valve cavity quickly pushes the valve stem upward, thus breaking contact with the valve seat and opening the outlet port. To close the valve again, the compressed air is vented from the actuator and the compression spring takes over again and pushes the valve stem down to seal the valve outlet. 
         [0006]      FIG. 1  shows on-off valves of this basic design that are known in waterjet cutting operations at water pressures up to 80,000 psi. The valve stem has a typical diameter of 0.076 inches and is made of hardened stainless steel. The valve seat is also made of hardened stainless steel and has an outlet of 0.035 inches in diameter, in general. The valve stem is generally centered with the help of a machined slotted shoulder, as shown in  FIG. 1 . A polymeric seal assembly and a metal backup disk seal the outside diameter of the valve stem. This valve design has been known in the waterjet industry for many years but its shortcomings become more apparent as the water pressure steadily increases. The poor reliability of the known valve stem and its valve seat, and the seal assembly is one major problem. The small outlet port and its associated fluid turbulence are other problems. Downstream fluid turbulence generated by a known small port can cause quality deterioration in the fluid jet generated at a downstream nozzle. 
         [0007]    Various attempts have been made to improve the capability of on-off valves used in water jetting processes. One of the more recent efforts is taught in U.S. Pat. No. 6,588,724 B2, the entire disclosure of which is incorporated into this specification by reference thereto, such as shown in  FIG. 2 . This known valve stem is divided into two parts, a floating cylindrical valve poppet completely immersed in the fluid and an actuating pin that engages the poppet in one end inside the valve cavity and the other end engages a force generator outside the valve cavity. The valve poppet has a central fluid passage that is advantageously utilized to control the flow of fluid between two cavities formed by the snugly fitted valve poppet inside a cylindrical valve cavity. By creating pressure imbalance between these two cavities with the actuating pin, the valve poppet is moved to seal or open the outlet port. The fluid force is advantageously used to move the valve poppet. This on-off valve represents a significant improvement over other prior conventional on-off valves and several shortcomings were eliminated. The floating valve poppet is significantly larger than the conventional valve stem and yet very easy to move with assistance from the pressurized fluid. A small valve poppet of this known on-off valve is typically 0.250 inches in diameter and its associated outlet port is generally 0.125 inches in diameter. Thus, there is no fluid erosion or turbulence. The valve poppet opens and closes the outlet by a water force, and thus the seating and lifting are both powerful but without impact. The actuating pin controls only the drain passage on the valve poppet and this passage is involved only in draining a very small amount of high-pressure fluid situated on top of the valve poppet. Thus, this valve would not have a fluid erosion problem. The external force required for sealing this drain passage on the valve poppet is considerably smaller than that of conventional valves. As a result, the overall reliability of this valve taught in the cited prior art is significantly improved. However, the external force required to move the actuating pin is still considerably higher than that available from a human hand. For example, the actuating pin taught by this prior art is typically 0.078 inches in diameter. This represents an external force of 96 pounds that is provided by a compression spring in order to close the valve at a water pressure of 20,000 psi, and a greater hand force is required to open the valve. This problem and a few other considerations prevented commercialization of this prior art despite its many good features. 
         [0008]    Referring to  FIGS. 3 and 4 , some of the most popular applications of high-pressure waterjet relate to material removal such as industrial cleaning, coating removal, concrete scarification, concrete repair and removal, and other geotechnical operations. In these processes, a waterjet is generally applied with a handheld lance having a hand-operated on-off valve. Currently, there are two types of valves in use in these lances. One is referred to as a “dump gun” and the other as a “shutoff gun”. In dump guns, the lance has two outlets, one that leads to the nozzle and the other that leads to a dump port. The hand-operated valve controls the dump port and is normally open. Water flows out the lance from both the nozzle and the dump port without much force. When the lance in put to work, the operator closes the dump port and the water pressure inside the valve cavity increases to the designed operating pressure. A powerful waterjet is then issued at the nozzle. The operator must keep the dump port closed to do the water jetting work and this task can be difficult in view of the design of the valve. The dump port is generally relatively large and the valve stem must also be relatively large. Thus, the sealing surface between the valve stem and the valve seat is very delicate and critical. Otherwise, the required hand force is unmanageable. The valve sealing must be positive and without leakage, otherwise high-pressure water gets into the sealing surface and creates powerful forces against the valve stem. This dump valve has one advantage that water pressure inside the valve cavity is generally low when the dump gun is in a standby mode so that no great force is needed to initiate the valve closing. Keeping the dump port closed is troublesome. Despite this well known shortcoming, dump guns are in wide use today because of the absence of alternatives. 
         [0009]    Referring to  FIG. 4 , the other type of popular known handheld waterjet lance is the shutoff gun. This type of lance has only one outlet port and is normally closed by spring force acting on a slim valve stem and is opened by a hand force acting on a trigger lever to force back the spring. A cam or piston transfers the force from the lever to the spring. Similar to an air-operated on-off valve discussed earlier, the external force required to open this type of lance valve is a function of the fluid pressure and the diameter of the valve stem involved. As the fluid pressure increases, the practicality of this type of valve decreases because the force requirement exceeds what the human hand can provide, despite the desirability of this type of valves. With the increased concern of conservation and scarcity of water in many parts of the world, a shutoff gun is preferred. 
         [0010]    There are other types of high-pressure on-off valves that are desirable if they can be operated by hand. A fast acting toggle valve, either momentary or definite, is one of these valves that could be particularly useful in laboratories and pilot operations, and can serve as a safety drain valve. Simple spring operated pressure regulating valves are highly desirable if they are sensitive to the fluid pressure involved but with the present valve technology, they are not available. 
       SUMMARY OF THE INVENTION 
       [0011]    It is one object of this invention to provide on-off valves that reduce or eliminate the shortcomings identified earlier. It is another object of this invention to provide on-off valves that are particularly useful in known high-pressure water jetting processes. This invention provides improved aspects of valve performance, including pressure capability, flow capability, reliability, ease of operation, ease of maintenance, and versatility. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    This invention is explained in greater detail below in view of exemplary embodiments shown in the drawings, wherein: 
           [0013]      FIG. 1  is a partial cross-sectional view of a fast acting on-off valve according to the prior art; 
           [0014]      FIG. 2  is a partial cross-sectional view of an on-off valve having a floating cylindrical valve poppet, according to the prior art; 
           [0015]      FIG. 3  is a partial cross-sectional view of a handheld lance having a hand-operated on-off valve for generating a high-pressure waterjet, according to the prior art; 
           [0016]      FIG. 4  is a partial cross-sectional view of a handheld lance having a hand-operated on-off valve, also according to the prior art; 
           [0017]      FIG. 5  is a partial cross-sectional view of a spring-to-close air-to-open on-off valve, according to one embodiment of this invention; 
           [0018]      FIG. 6  is a cross-sectional view of a valve assembly having a valve poppet and a valve cartridge, according to one embodiment of this invention; 
           [0019]      FIG. 7  is a partial cross-sectional view of a valve assembly similar to the valve assembly shown in  FIG. 6  but with a different valve poppet assembly; 
           [0020]      FIG. 8  is a cross-sectional view of a valve cartridge assembly similar to but different from the valve assembly shown in  FIG. 6 ; 
           [0021]      FIG. 9  is a cross-sectional view of a valve assembly having a valve cartridge similar to but different from the valve cartridge as shown in  FIG. 8 ; 
           [0022]      FIG. 10  is a partial cross-sectional view of an on-off valve assembly, according to another embodiment of this invention; 
           [0023]      FIG. 11  is a cross-sectional view of a portion of a valve assembly, according to another embodiment of this invention; 
           [0024]      FIG. 12  is a partial cross-sectional view of an on-off valve assembly, according to another embodiment of this invention; 
           [0025]      FIG. 13  is a cross-sectional view of a valve cartridge that can be used with the on-off valve as shown in  FIG. 12 ; 
           [0026]      FIG. 14  is a cross-sectional view of a valve cartridge having two tapered ends, according to one embodiment of this invention; 
           [0027]      FIG. 15  is a partial cross-sectional view of a hand-operated on-off valve used with a dump gun, according to one embodiment of this invention; 
           [0028]      FIG. 16  is a partial cross-sectional view of a shutoff gun, according to one embodiment of this invention; 
           [0029]      FIG. 17  is a partial cross-sectional view of a hand-operated toggle valve, according to one embodiment of this invention; 
           [0030]      FIG. 18  is a partial cross-sectional view of an on-off valve that can be operated with a solenoid, according to one embodiment of this invention; 
           [0031]      FIG. 19  is a cross-sectional view of a fluid pressure intensifier, according to one embodiment of this invention; 
           [0032]      FIG. 20  is a cross-sectional view of a pressure regulating valve, according to one embodiment of this invention; and 
           [0033]      FIG. 21  is a cross-sectional view of a portion of a pressure regulating valve system, according to one embodiment of this invention. 
       
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0034]    The apparatus and method of this invention successfully widens the participation of the pressurized fluid in operating an on-off valve. The water-induced force inside the valve cavity is advantageously utilized in both opening and closing the valve port, and in keeping the valve port opened or closed. As a result, the required external force in operating the valve is kept at a relatively low level, thus improving many aspects of valve performance and versatility. Referring to  FIG. 5 , one embodiment of this invention is a spring-to-close-air-to-open on-off valve of significantly improved performance as compared to known on-off valves. Valve assembly  100  comprises two basic parts, a valve cylinder assembly  101  and an air actuator assembly  131  connected together by a threaded collar arrangement that allows the two parts to be separated or connected quickly, such as for easy maintenance. The valve cylinder  101  has a side fluid inlet  102 , a bottom fluid outlet  103 , a central cylindrical valve cavity  104  that contains or houses a valve poppet  105 , a poppet spring  106 , a valve cartridge  107  and a valve inlet adapter  108  for use with a cylindrical valve cylinder. The actuator assembly comprises an actuator cylinder  131 , an upper end cap  132 , an air piston  133  with a diametrical seal  134 , a piston rod  135 , a compression spring  136 , an air inlet  137 , a cylinder coupler  138  with a seal  139 , and a coupling collar  140 . The air actuator assembly supplies the necessary force to move the piston rod, which transfers this force to the valve cartridge and to the valve poppet. The actuator assembly has a conventional setup in which a loaded compression spring  136  exerts a constant force on the air piston  133  and the piston rod  135  and ultimately to the valve poppet  105  to keep the outlet port closed. When compressed air of a specified pressure enters into the actuator cavity below the air piston  133  it pushes the piston upward to relieve the spring force on the valve poppet. The fluid force inside the valve cavity  104  will then push up the valve poppet  105  and open the outlet port. 
         [0035]    Referring to  FIG. 6 , which shows a more detailed view of valving parts of the valve assembly  100 , the valve poppet  105  and the valve cartridge  107  are separate parts. The valve poppet  105  can be a monolithic cylindrical body made of hardened stainless steel or an assembly of three connecting parts, including a larger upper shoulder  105 , a smaller lower poppet end  110  and a middle ball check valve  111 . There is a central fluid passage  109  in both upper poppet shoulder  105  and the lower poppet end  110 . The poppet spring  106  sits around the poppet end  110  and urges the poppet assembly  105  to move up. The valve cartridge assembly  107  has a tapered lower end  112  that mates with the valve cavity  122  to form a fluid-tight seal, a flat other end  113  extended beyond the valve cylinder  101 , a centrally situated actuating pin  114  having a fluid end  115  in contact with the poppet shoulder  105  and an intimate fit with the central fluid passage  109  and a flat end  116  in contact with a pin extension  117 , a polymeric pin seal  118 , and a pin bushing  119 . The valve actuating pin  114  and its seal  118 , the support pin bushing  119 , and the pin extension  117  are all situated in a central cavity  120 , of the valve cartridge  107 . The pin extension  117  is trapped inside the central cavity  120  with one end in contact with the actuating pin  114  and with the other end  121  extended outward. In its assembled form, the valve assembly  100  has the pin extension end  121  in contact with the piston rod  135  of the air actuator  131 . The spring force from the actuator is passed onto the poppet end  110  through the piston rod  135 , the pin extension  117 , and the actuating pin  114 . In conventional valves, there is generally only one rod that serves multiple roles of the piston rod, the actuating pin, and the valve stem. By dividing this rod into three separate segments, the required valve actuating force is significantly reduced because the only part exposed to the high-pressure fluid is the actuating pin  114 , which can be made with special materials, special precision, special support, and with a minimal diameter. The valve poppet  105  fits inside the valve cavity snugly but is free to slide up and down for a short distance and divides the valve cavity into an upper cavity  122  and a lower cavity  104 . In a normal closed state, the high-pressure fluid fills both cavities  122  and  104 . Because the valve poppet  105  has a tapered end  124  that is mated with the tapered outlet port  103 , the surface areas of the valve poppet  105  exposed to the fluid at the two ends are different. The end in the cavity  122  has a greater area exposed to the fluid than the end  124  in the cavity  104 . Thus, the fluid exerts a significant net force on the valve poppet  105  to close the valve outlet  103 . The fluid passage  109  in the center of the valve poppet  105  is closed by the actuating pin  114  with the external spring force. At this stage, the valve  100  is closed firmly with assistance from the fluid inside the valve cavity. The fluid force is relatively strong and can easily reach several hundred pounds even with a relatively small valve poppet and outlet port. For example, if the poppet has a diameter of 0.250 inches and the outlet port is 0.125 inches in diameter, the valve seating force is 245 pounds at a fluid pressure of 20,000 psi. A force of this magnitude cannot be supplied easily with an external spring or an actuator. 
         [0036]    Still referring to  FIG. 6 , when the spring force on the actuating pin  114  is lifted, the pressurized fluid in the cavity  122  lifts up the actuating pin  114 , thus exposing the passage  109  and causing the fluid in the cavity  122  to flow out rapidly. The check valve  111  is open in that direction. Thus, the cavity  122  loses the fluid pressure and the valve poppet  105  rapidly moves up to open the valve outlet port. The valve assembly  100  is now open and the high-pressure fluid flows in and out. The valve poppet  105  stays up with the help of spring  106  as the fluid pressure across the valve poppet  105  is equalized. The actuating pin  114  stays retracted as the fluid exerts a force to push it up to form a stable open position as long as the actuating pin  114  stays retracted. The check valve  111  in a two-part poppet construction can prevent the high-pressure fluid from entering into the cavity  122  prematurely and maintain the pressure imbalance across the valve poppet  105  a bit longer to assure complete poppet movement. By having the check valve  111 , the fluid has to move around the valve poppet  105  and the flow velocity is slowed with the close fit of the valve poppet inside the cavity  104 . To close the valve  100 , the spring force from the actuator  131  is resumed and the actuating pin  114  is again pushed down to move the valve poppet  105  downward to close the outlet port  103 . 
         [0037]      FIG. 7  shows another embodiment of this invention in which the valve assembly  200 , which is similar to the valve assembly  100  except in the valve poppet assembly. In the valve  200 , the valve actuator can be any suitable actuator and can be the actuator assembly  131  used in the valve assembly  100 . In the valve assembly  200 , all valving elements are integrated into one valve cartridge  210  that sits alone inside the valve cavity  204 . This valve cartridge  210  has a tapered outlet end  224  in contact with the valve outlet port  203  and has a flat end  213  in contact with the air actuator through a suitable coupler, such as the coupler  138  in the valve  100 . The valve cartridge  210  can be easily removed from the valve cavity by disconnecting an air actuator locking collar  140 . The cartridge end  213  has screwdriver slots to facilitate the removal. Thus, the necessary maintenance of the valve  200  is reduced to the replacement of the valve cartridge  210 , which can be a disposable item. 
         [0038]    Referring to  FIG. 8 , the valve cartridge  210  contains essentially the same components as that in the valve  100  except that these components are grouped inside a sealed cylindrical capsule. The capsule is made of a cartridge cylinder  210  and an end plug  207 . The cartridge cylinder  210  has a side fluid inlet  211 , an end fluid outlet  212 , a cavity  223  that contains a snugly fitted valve poppet  205 , which can be a monolithic one-piece poppet with a central fluid passage  209  or a 2-part poppet with a ball check valve  225 , similar to that of the valve  100 , and a poppet spring  206 . The check valve  225  allows fluid flow only in the direction from the cavity  222  to the outlet  212 . The cartridge end plug  207  has a central cavity  220  fitted with the valve actuating pin  214 , the pin extension  217 , the pin seal  218  and the pin bushing  219 . The actuating pin  214  has one end  215  in contact with the central fluid passage  209  of the valve poppet  205  and the other end  216  in contact with the pin extension  217 . The pin extension  217  has an other end  221  extended outside the valve cartridge end plug  207  through an end hole  227 . The valve cartridge  210  can have a tapered outside diameter like that shown in the valve  100  to seal off the fluid around the cartridge or an outside diameter of the seal assembly  226  for the same purpose. The operation of the valve cartridge  210  is essentially identical to that of the valve  100  except that the actuating pin  214  is now inside this cartridge and all parts are made with high precision and positioned to provide an exact movement in opening and closing the outlet  212 . The actuating pin  214  can be made with a minimal diameter and still be well supported and centered inside the valve cartridge. The pin extension  217  serves the purpose of trapping the actuating pin  214  inside the cartridge and of connecting it to the external spring force. The valve cartridge  210  is designed for top insertion into the valve assembly  200 . However, in some valves the valve cartridge is preferably inserted into a valve cavity from the front or the bottom of a valve cylinder or a valve body and is preferably used without an outside-diameter seal assembly. In such cases, the valve cartridge  310  can be provided according to this invention, as shown in  FIG. 9 . The valve cartridge  310  is essentially the same as the valve cartridge  210  except that the cartridge end plug  307  has a tapered end  313  and there is no outside-diameter seal assembly. By having two tapered ends, the valve cartridge  310  can be installed in a valve cavity with a minimal need for seals, as shown in other valve assemblies of this invention. This practice improves the maintenance of the valve assembly. 
         [0039]      FIG. 10  shows another embodiment of this invention as an on-off valve assembly that has a different way of moving the valving elements and can have further advantages in minimizing the external force required to operate the valve. The valve assembly  400  again comprises two major parts, an upper valve actuator assembly  430  and a lower valve cylinder assembly  401 . The valve actuator can be any suitable actuator or the actuator assembly  131  used in the valve assembly  100  of this invention. The valve cylinder assembly  401  has a side fluid inlet  402 , an end fluid outlet  403 , a cylindrical outlet valve cavity  404  associated with the outlet  403  and a cylindrical cocking cavity  405  at the opposite end connected by a passage  406 , a valve poppet  407  straddling across the two cavities, an end plug  408  that seals the cocking cavity  405 , a spacer spring  409  around the valve poppet  407 , and a bushing/seal assembly  410  around the poppet  407  in the cavity  404 . The end plug  408  has a tapered end  412  that seals the cavity  405  and a flat end  413  extended beyond the valve cylinder  401  to abut the actuator coupler  138 . The end plug  408  has a centrally situated valve actuating pin  414  and a seal assembly  415  and has a construction similar to that of the end plug  107  of the valve assembly  100 . 
         [0040]      FIG. 11  shows another embodiment, a valve assembly  400  which has a valve poppet  407  and in a position in the valve cavity  404 . The valve poppet  407  has a shoulder  416  and a shoulder seal assembly  417  that divide the valve cavity into two parts, an upper cavity  405  and a lower cavity  418  that has a small bleed hole  419  leading to the exterior of the valve cylinder  401 . This arrangement assures that the cross-sectional area of the poppet shoulder  416  remains larger than that of the poppet  407  inside the cavity  404 . When a pressurized fluid enters into both the cavity  404  and the cavity  405 , the fluid force exerting on the valve poppet  407  brings it down to close the valve outlet  403 . The seal assembly  416  on the poppet shoulder  415  prevents the fluid flow across the shoulder to the cavity  418 . Any fluid that leaks into the cavity  418  will be bled out of the valve assembly  400 . The poppet assembly  407  allows the fluid to be manipulated in and out of the cavity  405  to thus move the poppet  407  up and down to open and close the valve outlet. The actuating pin  414  is used to transmit an outside force from the piston rod  135  to the poppet shuttle  420 . The push-pull action of this outside force causes the high-pressure fluid to flow in and out of the cavity  405 , which in turn will cause the valve poppet  407  to close and open the valve outlet  403 . 
         [0041]    Still referring to  FIG. 11 , the valve poppet  407  comprises a poppet cylinder  407 , a poppet shoulder  416 , an end plug  426 , a poppet shuttle  420  with a central fluid passage  423 , a shuttle spring  425 , a shuttle seal assembly  424 , and a ball check valve  411 . The poppet cylinder  407  has a central cavity  430  housing the shuttle  420 , the shuttle spring  420  and the shuttle seal  424 . The cavity  430  is sealed on one end by the poppet shoulder  416  and the other end by the end plug  426 . The poppet shoulder  416  has a central hole  431  sized to accommodate one end  422  of the poppet shuttle  420  allowing it to slide. The other end  421  of the poppet shuttle  420  is in contact with the spring  425 , the seal  424 , and is in contact with a fluid passage  432  situated at the end of the poppet cylinder  407  that abuts the end plug  426 . The end plug  426  has a central cavity  427  and an outlet  428 . The cavity  427  contains or houses a ball check valve  411  that allows fluid to flow only from the passage  432  to the passage  428 . The poppet shuttle  420  has a shoulder  420  in the middle and two ends of smaller diameters, and has a passage  423  through its entire length. The poppet spring  425  abuts the poppet shoulder  420  and urges it to stay up against the poppet shoulder  416  and to seal the space around the passage  431  and the shuttle end  422 . This space around the shuttle end  422  and the poppet shoulder  416  allows fluid to pass from the cavity  430  to the cavity  405  when the shuttle shoulder  420  is not abutting the poppet shoulder  416 . The poppet cylinder  407  has the bleed hole  429  linking the cavity  430  to an exterior of the poppet cylinder  407 . 
         [0042]    Referring to  FIGS. 10 and 11 , in an assembled form, the valve assembly  400  is in a closed form as the external spring force pushes down the actuator piston, the piston rod, the actuating pin  414 , and the poppet shuttle  420 . The actuating pin  414  has an end  433  that engages the poppet shuttle  420 . When the actuating pin  414  pushes down the poppet shuttle  420 , the shuttle passage  423  is closed. At the same time, the fluid passage around the poppet end  422  in the passage  431  is open. When a pressurized fluid flows into the cavity  404  of the valve assembly  400 , it flows into the poppet cavity  430  and into the cavity  405 , thus exerting a force on the poppet shoulder  416  and pushes the valve poppet  407  down to close the valve outlet  403 . Because of the difference in cross-sectional area of the poppet shoulder  416  and the poppet cylinder  407 , the fluid induced force is quite strong and keeps the valve poppet  407  down and keeps the valve  400  closed. To open the valve  400 , one needs only to withdraw the external force on the actuating pin  414  and the fluid in the cavity  405  will quickly lose its pressure and the poppet  407  will quickly move up to open the valve outlet  403 . The poppet shuttle  420  will move up to abut the poppet shoulder  416  and to close the passage  431 . In this open position, pressurized fluid in the cavity  404  cannot flow into the cavity  405  because of the check valve  411  and the poppet seal/bushing assembly  410 . Thus, the cavity  405  has no high-pressure fluid and the actuating pin  414  is not under fluid pressure. This fact is important in initiating closure of the valve assembly  400  because a spring force large enough to push down the poppet shuttle  420  is able to initiate the valve closure. After that, fluid force will provide enough force to keep the valve  400  closed. The ease of valve closure in the valve assembly  400  of this invention separates it from other available on-off valves. Reviewing the design of this valve of this invention will show that success of the valve assembly  400  can depend on the design of the valve poppet  407  and on the valve shuttle  420 , in particular. The valve shuttle  420  is preferably made with a hard material and with high precision in its dimensions so that it can be moved inside the poppet cavity  430  with a small external force, even under a high fluid pressure. 
         [0043]    Referring to  FIG. 12 , a further embodiment of this invention is shown by the valve assembly  500  that is different from the valve assembly  400  in that all valving elements are now contained inside a valve cartridge  510  in a manner similar to that used in the valve assembly  200 . The valve assembly  500  has the valve cylinder  501  that has a central cylindrical cavity  504 , which is open in the actuator end and tapered in the outlet end, and has a side inlet  502  and an end outlet  503 . The valve cartridge  510  sits inside the valve cavity  504  with its tapered end  524  abutting the outlet  503  and its flat end  513  abutting an actuator coupler  540 . The actuator assembly  530  can be any suitable actuator or the actuator assembly  130  used in the valve assembly  100 . The valve cylinder  501  can also be similar to the valve cylinder  101  used in the valve assembly  100 . In such case, only the valve cartridge  510  is different. 
         [0044]    Referring to  FIG. 13 , the valve cartridge  510  used in the valve assembly  500  is an integrated form of valving elements found in the valve assembly  400 . In the valve  500 , a 3-part sealed cartridge comprises a cartridge cylinder  510 , an outlet end plug  524 , and an actuator end plug  508 . The three cartridge parts are sealed together to form the cavity  504  at the outlet end and the cavity  505  at the actuator end. The valve poppet  507  has a shoulder end  516  in the cavity  505  and an outlet end  524  in the cavity  504 . The valve cartridge  510  also contains all other crucial valving elements, such as an actuating pin  514 , a pin seal assembly  515 , a poppet seal/bushing assembly  520 , and a spacer spring  509 . The poppet shoulder  516  has an outside-diameter seal assembly  517  that divides the cavity  505  into two parts, an upper cocking cavity  505  and a lower ambient cavity  518 . A bleed hole  519  forms communication between the cavity  518  and the ambient. When the cartridge  510  is assembled inside the valve  500 , a system fluid flows into this valve from the inlet  502  into the valve cavity  504  and then flows into the valve cartridge  510  through the cartridge inlet  511  and into the valve poppet  507 . The system fluid can flow out of the cartridge  510  through the outlet  512  if the valve poppet  507  is in an up position. Otherwise, the fluid flow is stopped inside the cartridge cavity  504  if the valve poppet  507  is in a down position. 
         [0045]    Referring to  FIG. 14 , the valve cartridge  510  of this invention can be made to have two tapered ends to facilitate its use in certain applications. The result is the valve cartridge  610  has a tapered actuator end plug  613 . The valve cartridge  610  can have an outside-diameter seal assembly, such as in the case of the valve cartridge  510  or a tapered cartridge cylinder  610  to isolate the bleed hole  619  from the system fluid when the valve cartridge  610  is installed inside a valve cylinder. There are other ways to shape the valve cartridges of this invention to suit the design of a nozzle assembly, which is not critical to the operation of an on-off valve. As indicated earlier, the critical part is the design of the valving elements and how these elements work together. The two basic valving schemes and the cartridge approach of this invention can provide unique features to the valves. The cartridge approach simplifies the construction of on-off valves for serving different purposes. 
         [0046]      FIG. 15  shows a further embodiment of this invention, a hand operated on-off valve installed in a so-called dump gun that is popular in known water jetting operations. The valve assembly  700  is similar to the prior art shown in  FIG. 3  except that the valve assembly  700  of this invention uses a valve cartridge of this invention. Both the valve cartridge  310  and the valve cartridge  610  can be advantageously used in the valve assembly  700 . The valve assembly  700  comprises two basic parts, a valve body assembly  701  and a hand actuator assembly  730  tied together, such as by bolts. The valve body assembly comprises a valve body  701  having a threaded-on fluid inlet tube  702 , a fluid inlet passage  703 , a fluid outlet passage  704 , a valve cartridge cavity  705 , a valve cartridge  710 , a dump tube  707 , and a main tube  709 . The actuator assembly  730  can be in various forms because the hand force can be applied through various pivoted-lever devices or approaches. In the valve assembly  700  of this invention, the actuator assembly  300  comprises an actuator housing  730  equipped with cavities to accommodate a pivoted hand trigger lever  734 , an actuating piston  733  with a piston rod  735 , a piston return spring  736 , a hand grip  738 , and mounting bolts. The valve assembly  700  can also have an inlet adapter  739 , a trigger guard  740 , and a mounting bolt  741 . The selected valve cartridge  710  is pushed into the dump cavity  705  with the actuator end  713  first. The dump cavity  705  has a tapered end to mate with the cartridge end  713  to form a fluid-tight seal and has a central hole to allow the actuating pin  714  of the cartridge  710  to make contact with the actuator piston rod  735  when necessary. A dump tube  707  equipped with a proper seal assembly  708  and a tapered fluid inlet is threaded into the dump cavity  705  to engage the cartridge outlet end  724  to form a fluid-tight seal. The valve cartridge  710  is normally open as the actuator piston  733  is pushed away by the return spring  735  from the valve body  701 . When a pressurized fluid enters into the valve assembly  700 , it flows out from both the dump tube  707  and the main tube  709  without much force because both valve outlets are wide open. At this point, the valve assembly  700  is at a standby stage. When a water jetting task is to be performed, the operator applies a hand force to pull the trigger lever  734  toward the handle  738 . This action causes the actuator piston to move toward the valve body  701  and the actuator piston rod  735  engages the actuating pin  714  of the valve cartridge  710  and pushes it forward. The end result is the closure of the dump port  707 . Thus, the system fluid is routed to the main tube  709  to generate the desired waterjet at the nozzle, which is generally situated or positioned at an end of the tube  709 . To maintain the waterjet pressure, the hand force on the trigger lever  734  is continued. When the water jetting is to be stopped, the operator simply lets go of the trigger lever  734  and the valve cartridge  710  opens again to reduce the fluid pressure inside the valve. The hand force required for closing the valve cartridge  710  should ideally be minimized to avoid hand fatigue of the operator. 
         [0047]    One object of this invention is to reduce hand fatigue for the operator. In fact, the hand force required to close the valve cartridge  710  can be as little as a couple of pounds at a water pressure of 40,000 psi if the valve cartridge  610  is used, which cannot be accomplished with conventional dump guns. 
         [0048]      FIG. 16  shows a further embodiment of this invention, a shutoff gun that can be advantageously used in current water jetting operations. The shutoff gun can be used to shut off water flow at the gun completely and thus unloading or bypassing the pressurized water inside the hose can be performed somewhere else. The shutoff gun  800  is similar in construction to the dump gun assembly  700  shown in  FIG. 15  except that there is only one outlet tube and the valve actuator employs a different actuating mechanism. The shutoff gun  800  has a valve body  801 , a hand actuator assembly  830  attached to the valve body  801  by bolts, and a handle  842  attached to the actuator assembly  830 , such as also by bolts. An actuator assembly  830  comprises a body  830 , trigger lever  831  with an end pivot  832 , a central through-chamber  833  housing a front spring  834 , a spring piston  835 , a back spring  836 , a back spring piston  837 , a threaded set screw  838  and a pin  839 . A back spring tension adjustment bolt  840  is situated in the handle  838  and abuts the back spring  836 . The trigger lever  831  sits or is positioned between the front spring piston  835  and the back spring piston  837  and has a through hole  841  to accommodate the tension adjustment pin  839 . The trigger lever  831  is normally pushed toward the valve body  801  by the back spring  836  into a stopped vertical position. The back spring  836  exerts a known force on the front spring piston  835  through the tension adjustment pin  839 . The front spring piston  835  exerts a known force on the front spring  833 , which in turn sends the force to the valve actuating pin  814  of the valve cartridge  810  to close the valve outlet. 
         [0049]    Still referring to  FIG. 16 , the front spring  834  and its piston  835  can be used to create a constant force on the valve actuating pin  814  to engage itself at all times to the valve poppet inside the valve cartridge  810  so that the high-pressure water is kept out of the valve poppet even when the valve poppet is pushed away from the valve outlet by the pressurized water. Keeping the high-pressure water out of the poppet results in the valve actuating pin inside the valve cartridge  810  not always being confronted by the high-pressure water. Thus, the external force required to close the valve is reduced. In other words, the spring force from the back spring  836  is reduced. One result is easing the hand fatigue of the operator. 
         [0050]    Still referring to  FIG. 16 , the shutoff gun  800  is normally closed as the back spring  836  pushes the trigger lever  831  to a neutral position and the front spring  834  exerts a necessary force on the valve actuating pin  814  to push the valve poppet inside the valve cartridge to close the valve outlet port. Thus, there will be no water flow in the outlet tube. To open the shutoff gun assembly  800 , the trigger lever  831  is pulled toward the handle  842  until stopped by the stopper  843 . This action compresses the back spring  836  and also lessens or reduces the tension of the front spring  834  and thus the force on the valve actuating pin  814 . The reduction in the force on the valve actuating pin  814  is enough to cause the valve poppet to move away from the valve outlet port to open the outlet of the shutoff gun. At this point, the tension in the front spring  834  is reduced but not eliminated and thus allows the valve actuating pin  814  to be engaged to the valve poppet inside the valve cartridge. This feature is important in minimizing the hand force required for operating the shutoff gun assembly  800 . The hand force on the trigger lever can be maintained to continue water jetting and letting go of the trigger lever  831  will again shutoff the valve. In this operation, the hand force required to keep the valve open is a function of the back spring involved, which in turn is a function of the force required to close the valve. In a conventional shutoff gun, the required spring force is relatively high at high water pressures despite the use of a very slim valve stem, as discussed previously. In the shutoff gun assembly  800  of this invention, the situation is very different and a shutoff gun with a robust actuating pin and a relatively large outlet port is possible, without causing hand fatigue. This is particularly true if the valve cartridge  610  is used in the shutoff gun assembly  800  because a small force is needed for initiating valve closure as the actuating pin is not exposed to relatively high-pressure water at that moment. To keep the valve closed also needs no large external force because of assistance from the water. Thus, the shutoff gun assembly  800  is well suited for use in water jetting despite the fact that most conventional pumps in water jetting are crankshaft pumps that do not allow the output to be shutoff. A fast-actuating bypass valve can be used to shutoff guns. However, on-off valves of this invention can be advantageously used as a pressure-regulating valve, as later discussed. 
         [0051]      FIG. 17  shows a still further embodiment of this invention as a hand operated toggle valve  900 . A toggle valve is a hand valve that uses a lever to open and close a valve. It can be a momentary or a stable valve. Such valves are popular in low-pressure operations much like the toggle switches in electrical systems. At very high fluid pressures, toggle valves disappeared. It is one object of this invention to employ toggle valves. The valve assembly  900  of this invention can be momentary or stable, such as momentary open or momentary close, depending on the design of the cam mechanism. The valve assembly  900  shown in  FIG. 17  is a normally closed hand-to-open momentary valve. The valve  900  comprises of a valve cylinder assembly  910  and an actuator assembly  930 . The valve cylinder assembly  901  is similar or identical to the valve cylinder assembly  201 . The actuator assembly  930  has a spring cylinder  931  exerting a constant force on the piston  933  and the piston rod  935 , and to the actuating pin of the valve cartridge  210  inside the valve cavity. The spring cylinder  931  has a cam adapter  934  that provides a necessary force to push the piston  933  up against the valve-closure spring  936  in order to relieve the force on the valve cartridge  201 . A hand lever  941  connected to the pivotable cam  937  can be used in this invention, for this task. When hand lever  941  is pulled down, the cam  937  lifts the piston  933 . A small lift, such as 0.125 inches is sufficient to open the valve. A lever of 3 to 4 inches on the valve  900  can handle water at pressures up to 40,000 psi. If a momentary closed valve is desired, this cam mechanism can be mounted on top of the actuator cylinder  931 . If a stable on-off toggle valve is desired, the cam can be shaped to provide a stable open or close position and yet can still be operated by hand. This ease of operation in high-pressure on-off valves is possible with the minimal external force required to operate on-off valves of this invention. 
         [0052]      FIG. 18  shows a still further embodiment of this invention as an on-off valve that can be operated with an electrical solenoid and usable at very high fluid pressures. Because solenoids are not known to generate strong force at ordinary voltages and amperages, a solenoid-operated high-pressure on-off valve has not been available or used in water jetting processes. Because of the much reduced valve actuating force, an ordinary solenoid can be used in conjunction with a force-enhancing mechanism such as the cantilever employed in the valve assembly  900  of this invention. The valve assembly  1000  of this invention places a solenoid adapter  1042  on top of an actuator cylinder  931  and a selected electrical solenoid  1043  is employed to provide the necessary push force against a lever  1041 , which is connected to a pivotal cam  1037 . The cam arrangement is similar to that of the valve assembly  900 . The valve  1000  is normally closed by spring force from the actuator  1030 . When this valve needs to be opened, the solenoid  1043  is energized and a pushing force is generated in the solenoid piston  1044 , resulting in the pivoting movement of the lever  1041 . This movement is translated into a lifting force on the piston  1033 , thus relieving the force on the actuating pin of the valve cartridge  1010  opening the valve. A solenoid capable of generating 20 to 40 ounces of force and a travel of 0.125 inches or more can be advantageously used in constructing the valve assembly  1000  of this invention. 
         [0053]      FIG. 19  shows that one alternative to a cantilever force enhancement is a fluid pressure intensification that can also be used in constructing a solenoid-operated high-pressure on-off valve. The valve assembly  1100  of this invention can employ an electrical solenoid  1143  mounted directly on top of a spring actuator cylinder  1131 . Inside the cylinder there is a compression spring  1136  exerting a predetermined force on an actuator piston  1133  with a piston seal  1134 . The piston  1133  has an attached upper central cylinder  1144  with a cylindrical central cavity  1145  fitted with a solenoid piston rod  1146  and a rod seal  1147 . The cavity  1145  is connected to the actuator cylinder cavity  1148  below the piston  1133 . The piston rod  1135  is situated in the center of cavity  1148 , similar to other previously described actuators of this invention. The solenoid piston rod  1146  is attached to the solenoid piston  1149  and these two parts move together. The cavities  1145  and  1148  are filled with a selected hydraulic fluid to a pressure in balance with the force from the spring  1136 . In an assembled form, the spring  1136  applies a predetermined force on the actuating pin  1114  of the valve cartridge  1110  to close a valve outlet. To open the valve outlet, the solenoid  1143  is energized and the solenoid piston  1149  moves down and exerts a force on the fluid inside the cavity  1145 , thus increasing the fluid pressure. The increased fluid pressure is transmitted to the fluid inside cavity  1148 , thus creating a force pushing the piston  1133  upward. The lifted piston  1133  relieves the force of the valve cartridge  1110 , thus opening the valve outlet. By a difference in cross-sectional area of the solenoid piston rod  1146  and the actuator piston  1133 , the solenoid force is significantly enhanced. An area ratio determines the force enhancement. 
         [0054]    A still further embodiment of this invention is a pressure regulating valve shown in  FIG. 20 . Because of its relatively small size, high flow capability, high precision, high pressure capability, and high pressure sensitivity, the on-off valve of this invention can be used advantageously in fluid pressure regulating applications, particularly at high fluid pressures. By employing the valve cartridges of this invention, the regulating valves can be quite simple in construction, ideally suited for use in water jetting with multiple jetting lances or nozzles. A pressure relating valve is an on-off valve that is normally closed and is quickly open at a predetermined pressure. Once opened, it lets go or discharges with a predetermined amount of fluid, for example to return the fluid pressure inside the valve cavity back to a predetermined level. In water jetting with multiple hand-operated shutoff guns, the operators will operate their guns independently, thus affecting the fluid pressure in a supply hose. If all guns are open, there must be sufficient water in the supply hose to maintain the pressure. Likewise, if all guns are closed, the water inside the hose must have a dump port for water to be dumped to avoid over pressurization. Thus, a good pressure regulating valve is a necessary component in water jetting operations. If there is only one gun, one regulating valve will suffice. If there are four guns, four or more regulating valves can be needed to regulate the water pressure in the system. 
         [0055]    Still referring to  FIG. 20 , the regulating valve assembly  1200  of this invention comprises a valve cylinder  1201  integrated with the actuator cylinder  1231 , a catcher cylinder  1220 , and a drain plug  1223 . The valve actuator cylinder  1231  has a threaded-on end cap  1232 , the valve closure spring  1236 , the spring piston  1233 , the piston rod  1235 , and a spring spacer disk  1237 . The cylinder cap  1232  is threaded on to compress the spring  1236  to a predetermined compression so as to apply a predetermined force on the piston  1233  so that in an assembled form this spring force is transmitted to the actuating pin  1214  of the valve cartridge  1210  to keep the cartridge outlet closed. This spring force can be adjusted by changing the spring spacer  1237  without changing the spring. A thicker spacer disk  1237  will increase the spring force. The valve cartridge  1210  is positioned inside a valve cavity  1204 , which is connected to the fluid inlet  1202 . The fluid inlet  1202  can also be connected to outlets leading to nozzles or individual jetting lances. The outlet end  1211  of the valve cartridge  1210  abuts the catcher cylinder  1220  and is connected to a nozzle cone  1221  in which a selected nozzle orifice is mounted. This nozzle orifice is sized to match the nozzle size of a jetting lance, or sized according to some other predetermined formula. Below this nozzle cone is a catcher tube  1222  with a central cavity connected to a drain plug  1223  and the drain passage  1224 . The catcher tube  1222  catches fluid coming out of the nozzle cone  1221  and dissipates its energy. Therefore, the catcher tube is made of very hard materials and is capable of breaking up the fluid jet coming out of the nozzle cone  1221 . 
         [0056]    When a pressurized system fluid flows into the valve  1200  of this invention from a pump, it also flows to a nozzle or jetting lance to do work. The valve  1200  can be closed to maintain a constant system pressure. When the jetting nozzle is closed, the valve  1200  must quickly open to let go of a certain amount of fluid in the system and to restore the fluid pressure back to a predetermined level. The valve cartridges will automatically open or close according to the fluctuations of fluid pressure in the system and will try to maintain the preset level. This fluid pressure compensating operation should be performed inside a pump such as in the case of fluid pressure intensifier pumps. In such pumps, the hydraulic fluid is equipped with a pressure compensating valve that automatically monitors the load and adjusts the oil flow rate. Crankshaft pumps commonly used in conventional water jetting processes do not have this capability. Therefore, an external pressure sensing unloading valve is required and can be accomplished with the valve assembly  1200  of this invention. 
         [0057]      FIG. 21  shows a still further embodiment of this invention, which is a pressure regulating valve system  1300  for maintaining a pressure balance in a multiple-outlet high-pressure water jetting system. In such systems, there will be multiple water jetting guns that are operated independently. Thus, the water pressure can fluctuate violently in the system unless there is a suitable pressure regulating valve. For example, if there are four shutoff guns in a water jetting system, the pump must supply a sufficient amount of water to feed to all four guns in operations at a predetermined pressure. If one gun is closed, the regulating valve must release a certain amount of water to avoid over pressurization. If all four guns are closed, the regulating valve must let go of or discharge all of the water from the pump. Because the water jetting guns are operated at random the regulating valve must be able to meet the demand. One solution to this problem is to employ the regulating valve assembly  1300  of this invention. The valve assembly  1300  has multiple regulating valves mounted on a common valve body  1301 . The multiple actuators  1330  can have the springs  1336  set at a same spring rate or at different spring rates. The nozzle cones  1321  can have orifices matching, such as used in jetting guns or can be sized according to some other formula. By using a multiple pressure regulating valve of this invention, the valve assembly  1300  can meet the demand of conventional multiple-gun water jetting systems. 
       Example I 
       [0058]    A high-pressure on-off valve assembly was constructed according to the valve assembly  200  of this invention. This valve assembly comprised an air actuator part and a valve cylinder part locked together by a coupler and a locking collar, as shown in  FIG. 7 . The actuator cylinder, made of stainless steel, was 2.200 inches long, 1.250 inches in diameter, and had a 0.875-inch-diameter central cavity. The actuator piston, also made of stainless steel, was 0.875 inches in diameter and had an attached piston rod of 0.125 inches in diameter. The actuator piston was fitted with a diametrical O-ring seal. The actuator spring was a medium-duty die spring of 0.750 inches in diameter and 1.250 inches in length with a spring rate of 80 pounds at 0.31 inches compression. This spring was placed inside the actuator cylinder abutting the actuator piston on one end and the actuator end cap on the other end. The end cap was threaded into the actuator cylinder to compress the spring to 1.100 inches in length to produce a force of about 40 pounds. The actuator piston rod thus extended out of the actuator cavity. The coupler, made of stainless steel, was threaded into the actuator cylinder with the locking collar attached. The coupler had a locking shoulder of 0.800 inches in diameter and engaged a collar made of a 1.250 inch stainless-steel hexagon bar. The O-ring seal was provided to accommodate the piston rod. The actuator cylinder had a side fluid inlet that was fitted with a quick-connect nipple. 
         [0059]    The valve cylinder, made of hardened stainless steel, was 1.250 inches in diameter, 3.600 inches in length, and had an actuator end machined with external threads to engage the locking collar and an outlet end machined with internal threads to accept an outlet adapter. The valve cylinder had a central cavity of 0.375 inches in diameter and 2.450 inches in depth measured from the actuator end. This central cavity had a tapered outlet hole of 0.094 inches in diameter leading to the threaded outlet adapter cavity. The central cavity also had a side fluid inlet fitted with an inlet adapter to accommodate a hose or tube fitting. This valve cartridge was 2.600 inches long, 0.375 inches in diameter, and was made with stainless steel except for the seals. The valve cartridge case was made of two parts, a cartridge cylinder and an end plug. The cartridge cylinder had a central cavity of 0.250 inches in diameter and a side fluid inlet of 0.094 inches in diameter. This cartridge cylinder has a straight open end to mate with the end plug and had a tapered outlet end to mate with the outlet end of the valve cylinder. This central cavity accommodated a valve poppet with a 3-part construction, which had a shoulder of 0.250 inches in diameter and an outlet end of 0.188 inches in diameter, and was 1.0 inch long. The outlet end of the valve poppet had a compression spring of 0.750 inches in length and was compressed to urge the valve poppet away from the outlet. This valve poppet had a through fluid passage of 0.047 inches in diameter that was interrupted by a ball check valve of 0.078 inches in diameter, which allowed one-way fluid flow to the outlet. The tapered end of this valve poppet was designed to mate with the tapered outlet end of the valve cartridge to form a fluid tight seal. The valve poppet, although snugly fitted inside the cartridge cavity, was free to slide for a distance of about 0.100 inches. The end plug of valve cartridge also had a central cavity and a through hole to accommodate a centrally positioned valve actuating pin, a pin seal, a pin seal backup bushing, and a pin extension. One end of this end plug was cemented or adhered to the valve cylinder and the other end was flat and abutted the actuator coupler when assembled. This flat end of valve cartridge end plug had screwdriver slots to facilitate removal of the valve cartridge from the valve cylinder. The valve actuating pin had a diameter of 0.032 inches and a length of 0.85 inches, and was made of a relatively hard stainless steel. This valve actuating pin was locked inside the valve cartridge by the pin extension, which had one end extended outside the valve cartridge to engage the actuator piston rod when assembled. When assembled, the valve cartridge actuating pin extension had a length of about 0.200 inches outside the valve cartridge. The pin extension had a diameter of 0.094 inches. Pushing this pin extension into the valve cartridge would force the valve actuating pin to move the valve poppet toward the outlet and close the valve. 
         [0060]    In assembled form, the valve coupler was forced to abut the flat end of the valve cartridge by the threaded locking collar. Thus, the actuator piston rod forced the actuating pin to move the valve poppet to close the outlet port. This spring force was about 40 pounds. This spring force was adequate for this valve assembly to operate at a water pressure up to 45,000 psi. To open this valve would require compressed air of about 75 psi. 
         [0061]    Testing this valve with water at a pressure of 3,500 psi showed the expected performance. The response of this valve was fast and clean. There was no hesitation despite the relatively low water pressure. Movement of the valve poppet of this valve was a function of the fluid pressure, which determines the fluid force acting on the valve poppet. The higher the fluid pressure, the greater is the fluid force in seating the valve poppet and in opening the valve outlet. This force is relatively powerful at high water pressures and yet very gentle. There was absolutely no impact between valve parts. 
       Example II 
       [0062]    A hand-operated on-off valve was constructed according to the valve assembly  700  of this invention. This valve assembly was in the form of a dump gun commonly employed in conventional water jetting operations, as shown in  FIG. 15 . This dump gun comprised two major parts, the valve body assembly and the actuator assembly. The valve body assembly comprised a rectangular stainless-steel valve body 4 inches long, 2 inches wide and 1 inch thick, and a stainless-steel water inlet tube of 0.563 inches in diameter, 7 inches in length, and had threaded ends to engage the valve body and an inlet adapter. A valve cartridge was designed as shown in  FIG. 9 . A threaded-on short stainless-steel dump tube had an open end. A threaded-on 4 feet long stainless-steel main tube had an end nozzle. 
         [0063]    The actuator assembly comprised an aluminum-alloy actuator housing 1 inch thick, 2.5 inches wide, and 2 inches long. A stainless-steel pivoted trigger lever was 0.5 inches in diameter and 6.5 inches long. A stainless-steel actuating piston was 0.5 inches in diameter with a piston rod of 0.125 inches in diameter and an overall length of 1.2 inches. A piston return spring was 0.5 inches in diameter and 1 inch in length. An aluminum-alloy handle was 7.5 inches in length and ⅞ inches in diameter. There was also a stainless-steel inlet adapter, a stainless-steel trigger guard, and assorted stainless-steel mounting bolts. 
         [0064]    The valve cartridge was 0.5 inches in diameter, 2.6 inches in length, and had tapered ends, as shown in  FIG. 9 . The design of this valve cartridge was similar to that used in Example I except that it had greater dimensions but an absence of the outside seal assembly. The valve actuating pin was identical, 0.032 inches in diameter and 0.85 inches in length. When this valve cartridge was assembled inside the valve body, the ends formed a fluid-tight seal with the valve body on the actuator end and with a dump port adapter at the outlet end. The dump port adapter had a diametrical seal assembly on one end and a threaded cavity on the other end to accommodate the dump tube. The valve cartridge had its actuating pin extension exposed and positioned to engage the piston rod of the actuator assembly. There was also a main tube adapter threaded into the valve body on one end and engaged a main tube on the other end. Both tubes were 0.563 inches in diameter. The valve body had fluid passages connecting the inlet to the main-tube adapter and to the cartridge cavity. 
         [0065]    When assembled, the trigger lever was at a loose position and both outlet tubes were open to the inlet. When pressurized water flowed into the valve assembly, it flowed out of both tubes without much force because of the relatively large opening of the dump port. However, when the trigger lever was pulled toward the handle by hand, the actuating piston was pushed toward the valve body and the piston rod in turn pushed the valve actuating pin inside the valve cartridge to push the valve poppet to close the outlet. As a result, the dump port was closed and the water pressure inside the valve cavity rose quickly, and a high-speed waterjet was issued at the nozzle. The water jetting continued as long as the trigger lever was held by hand. The hand force required to hold the trigger lever was minimal, estimated at not more than 2 pounds at a water pressure of 40,000 psi. This hand force is considerably smaller than that required by any dump guns in use today, thus eliminating the hand fatigue problem. 
         [0066]    Testing this dump gun at a water pressure of 3,500 psi showed that this dump gun performed flawlessly. A similar result can be expected with a dump gun according to this invention, even at much higher water pressures. 
         [0067]    While in the foregoing specification this invention has been described in relation to certain preferred embodiments thereof, and many details have been set forth for purpose of illustration, it will be apparent to those skilled in the art that this invention is susceptible to additional embodiments and that certain of the details described herein can be varied considerably without departing from the basic principles of this invention.