Abstract:
Applicant provides a novel liquified booster pump. The pump takes high pressure boosted gas to a higher pressure. The pump is a pneumatically driven liquified gas booster pump with a shuttle valve enclosed within a body of the pump. Furthermore, the gas which is use to be boosted is carried from an inlet on the body of the pump to an outlet on the body of the pump, the boosted gas being carried entirely within the body of the pump with no external tubing. The pneumatically driven booster pump has a double ended piston within the central body and at least one shuttle valve incorporated in the piston for transferring gas from one side of the piston to the other.

Description:
This Application claims priority from U.S. application Ser. No. 60/178,014, filed Jan. 24, 2000. 
    
    
     FIELD OF THE INVENTION 
     An pneumatically driven liquified gas booster pump, more specifically described as a gas booster pump in which a shuttle valve is enclosed within the body of the pump and in which the driven or boosted gas is carried from an inlet to an outlet while entirely within the body of the pump. cl BACKGROUND OF THE INVENTION 
     Applicant provides novelty in a liquified booster pump. The function of a booster pump is to take high pressure gas and boost it to a higher pressure. This is sometimes beneficial in handling liquified gas such as liquified CO 2  or NO 2  in the fire extinguishing industry, air conditioning industry, paint ball, beverage, automotive, motorcycle and industrial gas industry. 
     All booster pumps have a high pressure inlet and a higher pressure (boosted) outlet. All booster pumps contain some sort of check valves. Some booster pumps use a double acting piston which boosts the inlet pressure on both strokes (2 boosts or 2 strokes in one complete cycle). With a balanced pump, working on both strokes of the same cycle, greater efficiency is typically realized. 
     Applicant&#39;s pneumatically driven liquified gas booster pump includes a piston body which piston body includes a shuttle valve enclosed within the body for controlling the drive gas and also includes internal boosted gas supply and transfer passages. Prior art booster pumps would typically have external boosted gas supply passages and external shuttle valves. Applicants booster pump also includes unique cartridge style double check valves within the body thereof for moving the gas to be boosted from an inlet to an outlet. 
     The way in which Applicant&#39;s booster pump works is that a piston is driven by a drive gas, which piston engages a pair of chambers in fluid communication with the gas to be boosted. On a double acting, balanced booster pump the drive gas is shuttled from one side to the other side of the primary piston. A primary piston face, is say, 4 sq. inches. The secondary or booster piston faces are smaller, say 1 sq.inch, resulting in a quadrupling of the force applied to the primary piston face. For example, if the drive gas pressure is 100 p.s.i. acting on 4 sq.inches of primary piston face, an increase to 400 p.s.i. is realized on the boosted gas. 
     Applicant uses a cartridge style double check valve that encloses the springs, balls and other elements of the double check valve within a cartridge, which cartridge will drop into the housing with “o” rings between the body of the booster pump and the double acting check valve so that all the gas must flow through the body of the double check valve. This saves machining on the body of the pump. 
     Applicant also provides an externally or manually operated shuttle valve reset assembly in case the shuttle valve is locked in an “in between” or “stalled” position, and provides also a momentary on-off switch. 
     Applicant further provides, as part of a booster pump system, a fill valve, to provide boosted gas pressure to a container such as a fire extinguisher cylinder. 
     Large tanks of high pressure liquified gas, called mother tanks, are often used to fill smaller tanks, or nurse tanks. For example, a mother tank of CO 2  may be used to fill many smaller fire extinguishers. Likewise, a large NO 2  tank may be used to fill many smaller NO 2  tnaks. 
     In such a system, the weight of the nurse bottle is often used to determine if it has been filled. For example, it may be known that a specific bottle type will weight 15 Lbs. when filled with NO 2 . When being filled from a mother bottle a booster pump may be used between the mother bottle and the nurse bottle. Periodic weighing of the nurse bottle during the filling process is required, often with the operator visually reading the weight from a scale and adding more gas as needed. 
     Applicant has further provided a consolidated system by joining a scale with a meter head display, in a package with the booster, hoses and valve. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an exploded top elevational view of Applicant&#39;s booster pump. 
     FIG. 2A (cross section through B:B),  2 B (end from the inside),  2 C (quarter section view) through C:C and  2 D are all elevational views of the valved pump end block body, one of the three body parts of Applicant&#39;s booster pump body housing  12 . 
     FIG. 3 is an side elevational side view of the center pump body of Applicant&#39;s body housing  12 . 
     FIG. 4A (viewed from the inside looking out),  4 C (side elevational) and  4 D (quarter section top elevational view D:D) are elevational views of the unvalved pump end block body of Applicant&#39;s 3 piece body housing  12  (there is not FIG.  4 B). 
     FIGS. 5A,  5 B and  5 C illustrate the 3 possible positions of Applicant&#39;s cartridge, that control which end of the piston assembly the drive gas will enter. 
     FIGS. 6 and 7 illustrate details of Applicant&#39;s cartridge stem assembly showing the two main pieces, the stem and the cartridge. 
     FIGS. 8 and 9 are views of the fill valves which are attached to a line connecting to the boosted gas outlet assembly. 
     FIGS. 9A and 9B illustrate an alternate preferred embodiment of Applicants fill valve. 
     FIGS. 10A and 10B show the details of Applicant&#39;s primary piston pump assembly and how it may be assembled from several pieces. 
     FIGS. 10C and 10D illustrate the alternate preferred embodiment of the primary piston pump assembly. 
     FIGS. 11A and 11B illustrate details of the double check valve cartridges of Applicants present invention. 
     FIG. 12 illustrates an alternate preferred embodiment of the booster pump assembly. 
     FIG. 13 illustrates the complete transfill station. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1 includes the major components of Applicant&#39;s booster pump  10 . The body housing  12  is typically made of 2024 extruded aluminum in three pieces: in FIG. 1 RDM- 86  (valved pump end body); RDM- 89  (center pump body) and RDM- 88  (unvalved pump end body). The three body pieces are typically held together by four hex head machine screws coming in from each end of the body and into the center body pump illustrated in FIG. 1 as HAR- 131 . 
     External to the body housing  12  and engaged therewith Applicant provides a high pressure gas inlet assembly  14  and a boosted gas outlet assembly  16 . These two assemblies are in fluid communication with the body as set forth in more detail below. The booster pump will take high pressure gas at the inlet and provide boosted pressure at the outlet. 
     Partially external to the body housing, and engaged therewith, Applicant also provides drive gas engagement assembly  30  which includes button VAL- 209 , the depression of which will supply drive gas to the pump to activate the pump. Optionally, partially external to the body housing and engaged therewith is threaded bolt HAR- 130 , the rotation of which will manually move the shuttle valve from a “stalled” position to an operating position. The operation of these parts will be explained in more detail below. 
     Also illustrated in FIG. 1 are the parts of Applicant&#39;s booster pump  10  that are enclosed within the body housing  12 . Here, Applicants provide a primary pump piston assembly  18  and a piston shuttle valve assembly  20 . The primary pump piston assembly  18  includes a drive piston  18 A having opposed drive faces  18 B and  18 C and two opposed driven pistons  18 D and  18 E, each one with a driven piston face  18 F and  18 G. The entire primary pump piston assembly  18  is integral and moves within the chambers of the body housing as set forth in more detail below. Cooperating and engaged with the primary piston pump assembly  18 , more specifically with drive piston  18 A by being slidably mounted thereto, is piston shuttle valve assembly  20 , the function of which is to controllably shuttle the drive gas from one side of drive piston  18 A to the other. 
     Turning back to the primary pump piston assembly  18  it is seen to fit within body housing  12 . More specifically center pump body RDM- 89  is machined to snuggly receive the drive piston, typically having an “o” ring  18 H engaged therewith so as to slideably seal against the walls of the body housing. Optionally, the drive piston “o” ring may be covered with a teflon cap seal to prevent rolling of the “o” ring (See FIGS.  10 C and  10 D). The drive piston may move back and forth in a drive piston chamber  22 , seen in FIG. 1 typically cylindrical and slightly larger in diameter than the diameter of drive piston  18 A. Likewise, both valved RDM- 86  and unvalved RDM- 88  end bodies are machined to create driven pistons chambers  24 A and  24 B, to receive the driven pistons  18 D and  18 E therein. “O” rings (or lip seals) are used throughout to create gas sealing while allowing primary pump piston assembly to move back and forth within the body. 
     It is also seen, with reference to FIG. 1 that the two end bodies RDM- 86  and RDM- 88  have shuttle valve chambers  26 A and  26 B to receive the ends  20 A and  20 B of the shuttle valve  20 . Note, as it will be explained in more detail below, that shuttle valve chamber  26 A is threaded at the near end thereof to receive the cartridge. 
     Optionally, applicant&#39;s shuttle valve engagement assembly  28  will allow the manual rotation of threaded bolt HAR- 130  to move end  20 B of piston shuttle valve assembly  20 . This occurs as, at the removed end of threaded bolt HAR- 130  there is a grooved shaft RDM- 118 , acting as a pinion gear to drive threaded rack RDM- 117 . One end of the threaded rack contacts the pinion gear and the other end contacts end  20 B of piston shuttle valve assembly  20 . More details on this follow. 
     Applicant&#39;s use a drive gas engagement assembly  30 , partially insertable into valved end body RDM- 86 . This assembly includes button VAL- 209 , retainer clip RDH- 21  and valve VAL- 208 . Valve VAL- 208  is available as an off the shelf item available from a number of sources. Button VAL- 209  acts against the protruding arm VAL- 208 A of Valve VAL- 208  (which is spring loaded) to depress the arm and thereby allow the drive gas to move through drive gas inlet port  32  out port VAL- 208 B, through inlet port  44  (See FIG. 2A) and into shuttle valve chamber  26 A. So long as the button is depressed the pump will operate. Release of the button by the operator will cause pumping to cease. 
     Applicant provides a pair of double check valve assemblies  34  (adjacent inlet) and  36  (adjacent outlet) Details of these will follow (See FIGS. 11A and 11B) below but note that they may be cartridges, dimensioned for receipt into valved chambers  38  (adjacent inlet) and valved chamber  40  (adjacent outlet). The two valved chambers are in fluid communication with their respective driven piston chambers  24 A and  24 B, through ports  25 A (See FIG. 2B) and  25 B (See FIG. 4A) so as to valve gas alternately under suction and compression within either chamber, through the respective double checked valve  34  and  36  assemblies as set forth in more detail below. 
     The remaining machining of the body housing is best understood with reference to FIG. 1 in conjunction with FIGS. 2A,  2 B,  2 C,  2 D,  3 ,  4 A,  4 C and  4 D. 
     Turning now to the valved pump end body RDM- 86  and FIGS. 1 and 2A,  2 B,  2 C and  2 D, it is noted that these illustrate various elevational views and will help understand the gas flow through the pump. 
     Drive gas comes into the valved end body at drive gas inlet port  32  from an appropriate fitting, through channel  32 A and enters drive gas assembly chamber  32 B, engages, and while in operation, passes through port VAL- 208 B, then through inlet port  44  to engage the shuttle valve and exhausts at either drive exhaust port  42 A or  42 B (See FIG. 2A) as set forth in more detail below. Shuttle valve end chamber  26 A receives pressurized drive gas from inlet port  32  through valve VAL- 208  through inlet port  44  to pressurize shuttle valve chamber  26 A, when button VAL- 209  is depressed. The shuttle valve chamber  26 A supplies a drive gas alternatively to both piston faces  18 B and  18 C (that is, into center pump body RDM- 89 ) as set forth in more detail below. 
     Again, with reference to FIGS. 1,  2 A,  2 B,  2 C and  2 D, and further with reference to FIGS. 3,  4 A,  4 C and  4 D, Applicant will provide details of the passages, vents, ports etc. that carry the driven or boosted gas from the intake assembly through the double check valves and, as boosted gas through the outlet assembly  16 . 
     Turning now to FIGS. 1,  2 C,  3  and  4 D, details of the manner in which the driven gas is moved through the body may be appreciated. More particularly, it is seen that the three body parts provide for driven (boosted) gas to be carried through the body along the high pressure passageway  48  or boosted gas passageway  50 . The double check valves operate in conjunction with the pneumatically driven primary pump piston assembly  18  to alternately fill driven piston end chambers, which are pressurized as driven pistons  18 D and  18 E alternately subject chambers  24 A and  24 B to pressure and suction, through each cycle of primary piston pump assembly  18 . 
     Turning now to FIG. 1 it is seen that high pressure passageway  48  has a first end  48 A at high pressure inlet, to align with port  14 A in the high pressure gas inlet assembly  14 , thus providing high pressure gas to valved chamber  40  through high pressure passageway  48 . Ports  34 A and  36 A of the respective double check valve assemblies provide suction pressure to chambers  38  and  40  respectively. Port  34 A draws gas through the inlet assembly  14  and upper end of check valve  34  when driven piston  18 D begins to move away from valved chamber  38  (suction). When driven piston  18 E begins to move away from valved chamber  40  suction develops in chamber  40  drawing gas through the upper end of check valve assembly  36 . On the other end port  34 A will vent driven piston chamber  24 A when driven piston  18 D begins to compress gas in driven piston chamber  24 A, and such compressed gas will pass out through the lower end of double check valve assembly  34  at first end  50 A of boosted pressure passageway  50 , to pass through the body and out at port  16 A of outlet port assembly  16 . The same action occurs at the other end of the pump as the piston reverse direction and piston chamber  24 B is under compression. Thus, the pump is “double acting,” boosting pressure at one drive piston chamber on each stroke of a two stroke cycle, while intaking gas at the other drive chamber. Thus it is seen that all the boosted gas must pass through one of the two double check valves. 
     Next, it remains to be explained the function of piston shuttle valve assembly  20  and related structure to explain how Applicants provide an internal shuttle valve to drive primary piston pump assembly  18 . This should be done with reference to FIGS. 1, with FIGS. 5A,  5 B,  5 C,  6  and FIG.  7 . Optionally, See FIGS. 10C and 10D for an alternate preferred embodiment. 
     Piston shuttle valve assembly  20  includes cartridge stem RDM- 90  onto which a 3 piece cartridge  61  is slidably received, the 3 piece cartridge being made up of a cartridge screw body RDM- 83 , a cartridge ring RDM- 77  and a cartridge body RDM- 79  (These 3 pieces can be manufactured as a single assembly, see FIGS.  10 C and  10 D). These are cylindrical, typically machined from brass, to slide over a body portion RDM- 90 A of cartridge stem RDM- 90 . Cartridge detent body RDM- 115  fits into the end of cartridge body RDM- 79  as seen in FIG.  7 . 
     Cartridge screw body RDM- 83  has three “o” ring groves: A, B and C and two vented grooves D and E. Cartridge ring RDM- 77  is comprised of a vented grove F and cartridge body RDM  79  has “O” ring groves G, H and I and vented groves J and K. Cartridge screw body RDM- 83  has threaded section RDM- 83 A which will thread into walls at the removed end (left end as viewed in FIG. 1) of shuttle valve chamber  26 A. Ball detent body RDM- 115  fits into the removed end of cartridge assembly  61  and includes on the interior walls thereof, ball detent grooves  115 A and  115 B. 
     Cartridge stem RDM- 90  has a central channel  90 B running through entire cartridge stem with removed ends  90 C and  90 D. The central channel is vented at ports  90 E and  90 F and has two holes cutting through the walls at  90 G and  90 H for holding the 2 detent balls  101 A and  101 B illustrated in FIG.  6 . (Alternate preferred embodiment, See FIGS.  14  and  14 A). The spring RDH- 100  is fittable into end  90 C of cartridge stem RDM- 90  into which detent pin RDM- 78  will fit, to act against the two balls  101 A and  101 B as illustrated in FIG.7 to normally maintain the cartridge stem in one of the two grooves  115 A or  115 B. Note that cartidge stem RDM- 90  has 5 “O” ring grooves  90 I,  90 J,  90 K,  90 L and  90 M, for receipt of “O” rings thereon. Further, the stem has bays  90 N and  90 O which are located in the exterior walls of the stem with bay  90 O vented by port  90 E. 
     Before turning to the operation of the shuttle assembly it must be pointed out that shoulders L and M on screw body RDM- 83  and cartridge body RDM- 79  respectively are dimensioned to receive the opposed outer walls of cartridge ring RDM- 77  such that when the  3  pieces of the cartridge  61 , RDM- 83 , RDM- 77  and RDM- 79  are pushed together as they would be when threaded into the end chamber  26 A of valved pump end body RDM- 86 , an annulus or circular gap  77 A is created. This gap will allow the passage of gas therethrough. The retainer clip and springs shown on FIGS. 1 and 7 (clips only on FIG.7) complete the structure of the piston shuttle valve assembly  20 . 
     Turning now to FIGS. 5A and 5B it is noted positions A and position B differ with respect to the position of the cartridge  61  with respect to the stem RDM- 90 . A close examination of position A (as set forth in FIG. 5A) will show that gas can pass through ports in vented groove F, bay  90 O through  90 E and into central channel  90 B. On the other hand, in position B (as illustrated in FIG. 5B) gas can pass through the annulus  77 A and out vented groove E. 
     When the cartridge  61  is threaded into the shuttle valve end chamber  26 A note the following alignment of vent grooves, with reference to FIG.  2 A: drive gas exhaust port  42 B aligned adjacent vented groove D; vented groove E aligned adjacent port  46 ; vented groove F aligned adjacent inlet port  44  and vented groove k aligned adjacent drive gas exhaust port  42 A. Vented groove J is not necessary to the operation of the shuttle valve. 
     It is understood that stem position A results when piston assembly  18  has moved to the left (as seen in FIG. 1) and that stem position B results when piston assembly  18  has moved to the right, as a result of the action of faces  18 C and  18 B respectively on the spring and retainer clip of stem RDM  90 . 
     When button Val- 209  is depressed and drive gas fills shuttle valve chamber  26 A and the stem is in position A, drive gas will enter through vented groove F, and the annulus  77 A from inlet port  44  and proceed into central passageway  90 B through port  90 E to pressurize the piston chamber from port  90 F so as to assert force against face  18 C. This will allow the piston assembly to move to the right as seen in FIG. 1, while the gas on the right side of piston body  18 A will escape through port  46 , into vented groove E across bay  90 N, through vented groove D and out exhaust port  42 B. Nearing the end of its movement to the right, face  18 B will act on stem RDM- 90  (against spring and retainer clip) to move it to position B. Now, from position B note drive gas in chamber  26 A will pressurize face  18 B when it rushes through vented groove E and port  46 . When piston body  18 A moves in response to this, to the left, as set forth in FIG. 1, gas will leave that end of the primary piston chamber through center channel  90 B, port  90 E and out exhaust port  42 A. 
     Thus, the piston moves back and forth so the shuttle assembly alternatively pressurizes one side of the piston body while venting the other. 
     Note that if the piston is “stalled” at the position indicated in FIG. 5C (annulus over an “O” ring), one may rotate threaded bolt HAR- 130  which will bump the stem off the the “O” ring. After that is done one should rotate HAR- 30  back to its original position. 
     FIGS. 8,  8 A and  9  show a nursing cylinder engaging fill valve  70 . The function of the nursing cylinder engaging fill valve is to shut off the boosted gas pressures provided to a nursing cylinder at the point of use. It is attached to the removed end of a line  73  attached to boosted gas outlet assembly  16 , (See FIG.1) at swivel connector housing  72 . Hand wheel  74  and stem  76  slideably engage and cooperate with swivel connector housing  72 . Spring RDH- 99 , stainless steel ball  75 , “O” rings SEA- 008  and SEA- 111 , retaining screw RDM- 92 , retaining spring RDH- 101  and activator pin RDM- 93  complete the assembly that is threaded into end  76 A of stem  76 . As illustrated in FIG. 9 boosted pressure gas has seated the ball against “o” ring SEA- 008 . However, when the user threads fill valve  70  onto a nurse container, by rotating hand wheel  74 , removed end RDM- 93 A contacts the valve of the nurse cylinder to be filled. Boosted gas will then move through port  72 A through chamber  76 B and into the nurse cylinder to be filled. Safety valve assembly  78  completes the fill valve and can be adjustably set by threadably adjusting body RDM- 66  into swivel body  72 . 
     FIGS. 9A and 9B illustrate an alternate preferred embodiment of a fill valve  70 A having an on\off knob  300  to shut off gas between the booster pump and a nurse cylinder before disengaging valve  70 A from the nurse cylinder. The on\off knob  300  is attached to a shaft  302 . A packing nut  304  acts on a bearing, such as flat plastic washer  306  against shoulder  302 A of the shaft end  302 B. Packing nut  304  is threaded into body  310 . Interconnect member  312  is threaded also into body  310  and has a shaft engaging portion  312 A for mating with shaft end  302 B. Interconnect  312  member also has a seat engaging portion  312 B for engaging drive seat  314 . When knob  300  is rotated so as to drive interconnect member  312  further into the body, drive seat  314  engages a spring loaded sliding seat  316  at open end  316 A. Sliding seat o-ring  318  is normally urged against shoulders  320  of body  310 . Boosted gas will normally flow into body  310  at boosted gas supply port  322  and through channel  316 B of sliding seat  316 . A retainer clip  324  normally retains spring  326 , which, with the boosted gas, urges the sliding seat against shoulders  320  and allows boosted gas flow through nurse cylinder supplied port  328  into the nurse cylinder. Threading knob  300  until it contacts end  316 A will shut off booster gas to the nurse cylinder. Further rotation, past this point, will unseat o-ring  318  and allow built up gas in the body and upstream of the nurse cylinder shut off valve (not shown) to escape through the walls between the sliding seat and shoulders  320  and out escape port  330 . Port  332  is a port for safety valve engagement for overpressurization of pressure from the booster pump. 
     Applicants provide unique fill valves typically for use in conjunction with the booster pump. Prior art teaches shutting off at the high pressure gas source at its source with subsequent loss of total system pressure (booster pump, lines, etc.). Applicants maintain system pressure and avoid this waste by providing fill valve  70  or any fill valve to control the flow of boosted gas at the point of use. Applicant also provides a safety valve assembly  78 , or any safety valve to guard against overpressurization from trapped liquified gases, held between the double check valves  34  and  36  (See FIG. 1) and the fill valve, when the pump is not in use. 
     Applicant&#39;s, in FIGS. 10A and 10B illustrate how the primary piston pump assembly  18  may be constructed from several pieces so as to use less metal and to allow for making the pieces from different metals. Threaded stud RDM- 34  engages threaded holes in stems  18 D and  18 E such that when tightened, the near ends of stems  18 D and  18 E seat against lips RDM- 81 A to provide a proper alignment of the stems with piston body  18 A. FIGS. 10A and 10B also illustrate the use of “O” rings to provide gas sealing. See FIGS. 10C &amp; 10D for an alternate preferred embodiment of primary piston pump assembly, which illustrate a single piece high pressure piston RDM- 205 , held in place by retaining rings LC- 87 . It further discloses how Teflon cap seal, SEA- 109  can be placed over o-ring SEA- 109 A to prevent it from rolling as the piston reciprocates inside of center pump body RDM- 89  (See FIG. 1 ). 
     Applicant&#39;s, in FIGS. 11A and 11B, illustrate how the double check valve assemblies are constructed. Housing RDM- 76  includes port  34 A/ 36 A. Two check screws RDM- 75  are threaded into the body through removed end RDM- 76 A seating the two balls A and B and two springs RDH- 99  as indicated, while also backing the two “O” rings SEA- 008 . Pressurized gas can enter end RDM- 76 A. Suction at port  34 A/ 36 A will unseat ball A and allow gas to go through port  34 A/ 36 A. Pressure at  34 A/ 36 A will unseat ball B and allow gas to flow out end RDM- 76 B. The o-rings SEA- 012  provide for a fluid tight seal between cartridge  34 / 36  and chambers  38 / 40 . Thus, Applicant provides, in a cartridge, a double check valve. 
     FIGS. 12 discloses a bottom view of the alternate preferred embodiment of the booster pump disclosed in FIG.  1 . However, there are three differences as set forth in more detail below. 
     Upon closer examination of booster pump  400  as disclosed in FIG. 12, we see Applicant has provided a single piece shuttle cartridge  402  instead of the three piece cartridge  61  disclosed in FIG.  6 . In the single piece shuttle cartridge  402 , optional narrow slots are employed in the transfer of the drive air instead of the annualar gap created by the three individual pieces of cartridge  61  in FIG.  6 . It is also noted in relation to the single piece shuttle cartridge  402  how Applicant has provided a very close tolerance fit between outer walls  402 B and mating internal walls of port  406 A in valved end body block  406 , resulting in a nearly complete fluid tight seal between the vented bays of cartridge  402  while significantly reducing the number of o-ring seals needed to operate the pump. The small amount of bypassing drive gas does not affect the performance of the pump. 
     Another difference of the alternate preferred embodiment  400  is noted in the detent assembly  408 , including detent balls  408 A and ball housing  408 B, and compression springs  408 C to urge said balls towards the annular detent grooves  412 A on removed end of shuttle tube  412 . As can be seen in FIG. 12, valved end pump block  406  has been machined at port  406 B for the receipt therein of detent assembly  408 , which, at the removed end of port  406 A, provides force on the outside of annular detent grooves  412 A of shuttle tube  412 . Thus it can be seen how Applicant has provided for internal detent grooves in one disclosure (FIG. 7) and external detent grooves in the alternate embodiment (FIG.  12 ), however the function of holding the shuttle tube into one position or the other is demonstrated in both embodiments. 
     In the final disclosure of FIG. 12, Applicant has provided double check valve assemblies  414  and  416  produced from individual valve components instead of the cartridge type disclosed in FIGS. 11A and 11B. These alternate check valve assemblies  414  and  416  function similar to previous disclosure  34 / 36  (See FIG. 11B) by allowing suction pressure into the high pressure chamber thru the first valve and allowing boosted pressure to escape thru the second valve on the compression stroke of the pump. However, instead of using balls to seat against o-rings as disclosed in FIG. 11B, Applicants alternate embodiment create the first valves using piston  418 / 420  in conjunction with o-rings  422 / 424  respectfully, to seal against flat surfaces  426 A/ 404 A on stationary tube  426  and unvalved end block  404 , respectfully said pistons urged by compression springs  428 / 430 . The secondary valves are created using pistons  432 / 434  in conjunction with o-rings  436 / 438  to seal against removed end  440 A/ 442 A respectively of stationary valve guides  440 / 442  respectively, with springs  444 / 446  urging said pistons towards their respective sealing surfaces. The remaining o-ring seals and outlet fittings are provided as static fluid tight seals in view of pump operation. 
     In FIG.13 Applicant discloses a transfill station  210 . The function of the transfill station is to provide a single integral assembly for filling, from mother tank containing high pressure gas, to a nurse cylinder with liquified gas or a gas at a boosted pressure. What the prior art lacks is a single assembly which locates and supports the elements necessary for filling a nurse tank or cylinder at a boosted pressure from the gas or liquified gas, of a mother tank. 
     A mother tank  200  contains a high pressure gas such as CO 2  or NO 2 . A high pressure supply line  202  is connected to the mother tank through a mother tank connection  201 . The removed end of the high pressure supply line  202  is attached to the high pressure inlet assembly  14  of a booster pump such as Applicant&#39;s booster pump  10  (or any other booster pump). A boosted gas supply line  204  is attached at one end to the boosted gas outlet assembly  16  of the booster pump. At the removed end of the boosted gas supply line is a nurse cylinder fill valve such as, for example, alternate preferred embodiment of fill valve  70 A (See. FIG.  9 B), or any other fill valve. A nurse cylinder  206  will be filled using Applicant&#39;s unique transfill station  210 . The fill valve may contain a safety valve  208  to prevent over pressurizing the hose (See FIG. 9B for further details of a safety valve). 
     Applicant&#39;s unique transfill station  210  includes a tray or platform  212  on which a number of elements are mounted. This tray or platform provides for a base and a physical location of the elements of the transfill station that make the transfill station a simple, easy, affordable and self-contained unit for filing a nurse cylinder from a mother cylinder. 
     Onto the tray or platform  212  is mounted a booster pump such as Applicant&#39;s booster pump  210  or any other booster pump. The booster pump typically includes the high pressure supply line and the boosted gas supply line  202  and  204  respectively. Also, at the removed end of the boosted gas supply line is typically located a fill valve. 
     Adjacent to booster pump and mounted to the tray platform is a scale, for measuring the weight of the nurse bottle or nurse cylinder which is typically placed on the upper surface thereof. The scale includes an upper platform  218  for placement of the nurse bottle thereupon and typically mounted below the upper platform a sensor  220 , which will provide an output signal, the output signal a function of the weight of the bottle or nurse cylinder placed on the scale. Connection by an appropriate wire conductor to the sensor is a meter head controller  216  which will display the weight of whatever is placed upon the scale. 
     Meter head controllers and scales are commercially available from known sources. Applicant has provided, in a single integral unit, a tray or platform for mounting a booster pump scale and a scale readout or meter head controller thereon. This unit, with the appropriate supply line provided, means that a user may easily transport the unit and has all the elements necessary for filling a nurse cylinder from a mother cylinder. Mother cylinders are often large and unweildly so Applicant provides, in a single transfill station  210  a scale, scale readout, booster pump and the necessary lines to connect the booster to the mother cylinder and the nurse cylinder. 
     Although the invention has been described with reference to specific embodiments, this description is not meant to be construed in a limited sense. Various modifications of the disclosed embodiments, as well as alternative embodiments of the inventions will become apparent to persons skilled in the art upon the reference to the description of the invention. It is, therefore, contemplated that the appended claims will cover such modifications that fall within the scope of the invention.