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A wide variety of mud pump rubber piston assembly options are available to you, such as 1 year, not available.You can also choose from new, mud pump rubber piston assembly,As well as from energy & mining, construction works , and machinery repair shops. and whether mud pump rubber piston assembly is 1.5 years, 6 months, or unavailable.

Explore a wide variety of mud pump piston on Alibaba.com and enjoy exquisite deals. The machines help maintain drilling mud circulation throughout the project. There are many models and brands available, each with outstanding value. These mud pump piston are efficient, durable, and completely waterproof. They are designed to lift water and mud with efficiency without using much energy or taking a lot of space.

The primary advantage of these mud pump piston is that they can raise water from greater depths. With the fast-changing technology, purchase machines that come with the best technology for optimum results. They should be well adapted to the overall configuration of the installation to perform various operations. Hence, quality products are needed for more efficiency and enjoyment of the machines" full life expectancy.

Alibaba.com offers a wide selection of products with innovative features. The products are designed for a wide range of flow rates that differ by brand. They provide cost-effective options catering to different consumer needs. When choosing the right mud pump piston for the drilling project, consider factors such as size, shape, and machine cost. More powerful tools are needed when dealing with large projects such as agriculture or irrigation.

Alibaba.com provides a wide range of mud pump piston to suit different tastes and budgets. The site has a large assortment of products from major suppliers on the market. The products are made of durable materials to avoid corrosion and premature wear during operations. The range of products and brands on the site assures quality and good value for money.

Bonded-Nitrile Pistons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Replaceable Nitrile Pistons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Mud-Pump Gear Sets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

The 2,200-hp mud pump for offshore applications is a single-acting reciprocating triplex mud pump designed for high fluid flow rates, even at low operating speeds, and with a long stroke design. These features reduce the number of load reversals in critical components and increase the life of fluid end parts.

The pump’s critical components are strategically placed to make maintenance and inspection far easier and safer. The two-piece, quick-release piston rod lets you remove the piston without disturbing the liner, minimizing downtime when you’re replacing fluid parts.

For drilling companies with the need to pump slurries with bentonite, concrete, and other thick mud, Elepump triplex, high pressure piston mud pumps are the ideal choice for long life and minimal maintenance.

Featuring superior construction and high quality materials, Elepump mud pumps are built to last. They require minimal maintenance, so your costs stay low so and your drilling operations stay profitable.

The KT-45 mud pump is the most compact of the whole range of Elepump pressure pumps. This small capacity pump is still mighty enough to pack a big punch, with enough flow for drilling up to HQ sizes. It is very light and very maneuverable, making it a great choice for geotechnical drilling, fly jobs or heliportable jobs. Elepump mud pumps can be configured for diesel, gas, electric and air power.

The KF-50M is the pump to choose if you want a pump you can count on to keep pumping without missing a beat. This powerful pump is a standard size and can handle all slurries including bentonite, concrete and more. With its stainless steel ball and seat style valves, it is the ideal choice for pumping grit, cement, chunks of rock and other hard material, without the worry of damage to fragile parts. Elepump mud pumps can be configured for diesel, gas, electric and air power.

The joints between drywall sheets are typically filled and sealed with strips of paper or fiberglass mat and drywall joint compound, also called “joint compound”, “drywall mud”, or just “mud”. Joint compound may be made, for example, of water, limestone, expanded perlite, ethylene-vinyl acetate polymer and attapulgite. Joint compound is applied as a viscous fluid that is thick enough to maintain its shape while it hardens. In addition to forming joints, drywall mud is used to cover nail or screw heads, form a smooth or flat surface, and provide a texture over the surface. Paint or wall paper is typically applied over the drywall and joint compound.

Workers often specialize in the installation of drywall, and in large projects different crews install the drywall panels (drywall hangers) from those who finish the joints and apply the joint compound (tapers or mudmen). Workers who specialize in drywall installation often use specialized tools to increase their productivity including flat boxes that are tools used to hold joint compound and apply it to drywall joints. Joint compound is often mixed (e.g., with water) or stored in buckets, and drywall mud pumps have been used to pump the mud from the buckets into flat boxes or other tools or containers.

U.S. patent application Ser. No. 11/292,238, publication 2007/0122301 (also by Werner Schlecht) describes a drywall mud pump. However, it was found that in operation pumping drywall joint compound that friction developed within the pump making it difficult to use. Thus, needs or potential for benefit exist for drywall mud pumps that have less internal friction. In addition, needs and potential for benefit exist for drywall mud pumps that are inexpensive to manufacture, reliable, easy to use, that have a long life, that are easy to service and clean, and that are simple in operation so that typical operators can effectively maintain them. Room for improvement exists over the prior art in these and other areas that may be apparent to a person of ordinary skill in the art having studied this document.

This invention provides, among other things, certain drywall mud (drywall joint compound) pumps with particular features or capabilities. Various embodiments provide, as objects or benefits, for example, that they have less internal friction than certain prior art pumps. In addition, particular embodiments provide, for instance, as objects or benefits, drywall mud pumps that are inexpensive to manufacture, reliable, easy to use, that have a long life, that are easy to service and clean, that are simple in operation, or a combination thereof. Other benefits of certain embodiments may be apparent to a person of ordinary skill in the art.

In specific embodiments, this invention provides certain drywall mud pumps that include a main cylinder and a rod having two ends, a first end and a second end. In many embodiments, when the drywall mud pump is assembled, the second end of the rod is located within the main cylinder, for example. Various embodiments also include a piston which, when the drywall mud pump is assembled, is also located within the main cylinder and is attached to the second end of the rod. In some embodiments, there is a connection structure between the piston and the second end of the rod, which is configured to allow the second end of the rod to move relative to the piston in a direction that is substantially perpendicular to the axis of the rod. A number of embodiments include a means for allowing the second end of the rod to move laterally relative to the piston within the main cylinder. Further, in some embodiments the piston specifically includes an elongated hole that receives the second end of the rod, and the elongated hole allows the second end of the rod to move laterally relative to the piston.

Various such embodiments further include a pump head, which may have an output aperture, and when the drywall mud pump is assembled, the pump head may be connected to the main cylinder and the rod may pass through the pump head. In some embodiments, the drywall mud pump further includes a handle and a linkage, and when the drywall mud pump is assembled, the handle may be pivotably connected to the first end of the rod, and the linkage may be pivotably connected to the pump head and pivotably connected to the handle, as examples. Moreover, some embodiments may include (e.g., in the pump head) a means for guiding the rod, a means for allowing the rod to pivot as the second end of the rod moves laterally relative to the piston, or both. Further, particular embodiments include a guide having a hole through which the rod slidably passes. Some embodiments include just one guide in the pump head, which may serve as both a guide and as a pivot point for the rod, and in some embodiments, the guide may be shortened to provide for pivoting.

In a number of embodiments, the piston includes an elastomeric piston cup having a first hole, which may be elongated, a top rigid support having a second elongated hole, a bottom rigid support having a third elongated hole, and a flapper having a fourth elongated hole. In some embodiments, when the drywall mud pump is assembled, the second end of the rod passes through each of the first, second, third, and fourth holes, for example. Further, certain embodiments include a means for preventing the piston from rotating about the rod. In some embodiments, as an example, the second end of the rod has a flattened portion, at least the second and third elongated holes are substantially the same size and have substantially the same shape, and, when the drywall mud pump is assembled, are held in a particular orientation by the flattened portion of the second end of the rod.

Even further, in some embodiments, when the drywall mud pump is assembled, the second end of the rod is attached to the piston with a nut (e.g., a lock nut), an elongated washer, or both. Moreover, in some embodiments, the piston cup, the top rigid support, and the bottom rigid support each have at least one passageway therethrough for passage of the drywall mud, and when the drywall mud pump is assembled, the flapper covers the (at least one) passageway substantially blocking passage of the drywall mud when the piston is moving in the main cylinder toward the pump head.

In various embodiments, the piston cup, the top rigid support, and the bottom rigid support each have multiple passageways therethrough for passage of the drywall mud, and the multiple passageways substantially surround the first, second, and third elongated holes. In addition, in some such embodiments, a plurality of the multiple passageways for passage of the drywall mud have at least one curved side and at least one straight side. Additionally, in particular embodiments wherein an elongated washer is provided, when the drywall mud pump is assembled, the washer substantially blocks the elongated hole in the piston to prevent drywall mud from passing through the elongated hole in the piston. In a number of such embodiments, the drywall mud pump may also include a means for controlling the rotational position of the washer.

Further, in some embodiments, the second end of the rod includes a first reduced diameter flattened section and a second reduced diameter flattened section. In some such embodiments, for example, the second reduced diameter flattened section has a smaller diameter, thickness between flats, or both, than the first reduced diameter flattened section. Further, in some embodiments, the second end of the rod also includes a threaded section. Further still, in some embodiments, when the drywall mud pump is assembled, the second end of the rod passes through each of the first, second, third, and fourth elongated holes such that the fourth elongated hole is located at the first reduced diameter flattened section, and the first, second and third elongated holes are located at the second reduced diameter flattened section. In addition, various other embodiments of the invention are also described herein.

FIG. 7 is an isometric exploded view of the piston, rod, and pump head of the example of a mud pump of the previous figures, except that the piston in FIG. 7 is not shown exploded;

FIG. 1 illustrates an example of an assembled drywall mud pump, pump 10. Parts and features that are visible from the outside in this view include output aperture 11 in pump head 14 where drywall mud emerges from pump 10 when handle 12 is moved, for example, by an operator of drywall mud pump 10. In some embodiments, a detachable high filler (not shown) may attach to aperture 11 (e.g., with the nuts 11nshown) and may extend the location where the mud emerges to a higher elevation to enhance ergonomics. FIG. 2 is an exploded view of the same embodiment of drywall mud pump 10 shown in FIG. 1.

In the embodiment illustrated, rod 13 passes through pump head 14 (visible in FIG. 1 through aperture 11) into main cylinder 15. Pump head 14 is mounted on or connected to main cylinder 15, in this embodiment, with clips 25. Also in this embodiment, handle 12 is pivotably connected to the top or first end 21 of rod 13 with pin 23, and linkage 16 is pivotably connected at the top (of linkage 16) to handle 12 and at the bottom (of handle 16) to pump head 14 with bolts 26.

Other visible parts of pump 10 include foot plate 18, which is connected to pump head 14 with bolts 28, in this embodiment, and foot valve 19, which is connected to the bottom end of cylinder 15 with pin 29. When in use, main cylinder 15 may extend into a bucket of drywall joint compound or mud while foot plate 18 may extend outside of the bucket to the floor. The operator may place his foot on foot plate 18 to steady pump 10 while moving handle 12. Foot valve 19, in the bottom of the bucket, may form or include a check valve that may allow mud to flow upward into cylinder 15, but may substantially prevent mud from flowing downward out of cylinder 15 through foot valve 19. Rod 13 also passes through shortened guide 17, in this embodiment, and guide 17 is attached to pump head 14 with bolts 27. Thus, guide 17 is easily removable and replaceable.

FIG. 2 also introduces piston 20, which, in this embodiment, includes several different components that will be discussed in more detail with reference to other figures. In this embodiment, when drywall mud pump 10 is assembled, piston 20 is located within main cylinder 15 and is attached to the bottom or second end 22 of rod 13. In addition, when drywall mud pump 10 is assembled, second end 22 of rod 13 is also located within main cylinder 15. When an operator pushes handle 12 down, piston 20 goes up toward pump head 14, pushing drywall mud that is in cylinder 15 out through aperture 11. During this process, a vacuum is created below piston 20, which draws more drywall mud into cylinder 15 through foot valve 19. When the operator pulls handle 12 up, piston 20 goes down, away from pump head 14, foot valve 19 prevents the drywall mud below piston 20 from exiting cylinder 15 through the bottom, and drywall mud flows through piston 20, as will be described in more detail below.

During the operation of mud pump 10, horizontal or lateral forces are exerted on rod 13. Even if the operator only exerts vertical forces on handle 12, since linkage 16 is not vertical during most of the stroke of piston 20, linkage 16 exerts lateral forces on handle 12, which are carried by handle 12 to rod 13. These horizontal or lateral forces on rod 13 are believed to cause increased friction or binding within prior art drywall mud pumps. In a number of embodiments, drywall mud pump 10, and various other drywall mud pumps in accordance with this invention, allow rod 13 to move laterally without binding (or with reduced binding) and in a manner that reduces friction (e.g., within mud pump 10). In different embodiments, such a reduction in friction makes the drywall mud pump (e.g., 10) easier to use. In addition, in many embodiments, reduced friction reduces wear, thus increasing pump life, maintaining a level of pump performance for a longer time, reducing the need for replacement of parts, reducing the need for servicing of the pump, or the like.

FIG. 3 is a closer view of assembled piston 20 attached to second end 22 of rod 13. FIG. 4 is an exploded view of piston 20 and rod 13, and shows the components of piston 20 and details of second end 22 of rod 13, in the embodiment illustrated. In this embodiment, piston 20 includes nut 41, elongated washer 42, bottom wiper support 43, piston seal, wiper, or cup 44, top wiper support 45, and flapper 46. In some embodiments, a means may be provided for preventing nut 41 from turning or loosening once nut 41 is installed. In many embodiments, for example, nut 41 is a lock nut (e.g., having a nylon insert), but in other embodiments, nut 41 may be a regular (hexagonal) machine nut. In some embodiments, nut 41, piston 20, or rod 13 may include a cotter key, set screw, jam nut, lock washer, or the like, to prevent nut 41 from turning once installed. Further, in other embodiments, a bolt, machine screw, snap ring, other fastener, or the like, may be provided instead of nut 41.

In a number of embodiments, piston cup 44 may be an elastomeric material such as rubber or a synthetic equivalent thereof. Other components shown in FIGS. 3 and 4 may be metal, such as steel, stainless steel, brass, bronze, aluminum, or the like, or may be made of a plastic, a polymer, or nylon, for example. In the embodiment illustrated, piston cup 44 has an outside diameter that is slightly larger than the inside diameter of main cylinder 15. Thus, an interference fit may exist between piston cup 44 and main cylinder 15, and when piston 20 is inside main cylinder 15 (e.g., when drywall mud pump 10 is assembled), the outside diameter of piston cup 44 may contact the inside surface of main cylinder 15.

Bottom wiper support 43, in this embodiment, has an outside diameter that is less than the outside diameter of piston cup 44, and slightly less than the inside diameter of main cylinder 15. Bottom wiper support 43 may be rigid, may provide support to piston cup 44, and may have a clearance fit with main cylinder 15. Top wiper support 45, in this embodiment, has an outside diameter that is less than the outside diameter of piston cup 44, less than the inside diameter of main cylinder 15, and may have an outside diameter that is less than (or equal to) the outside diameter of bottom wiper support 43. Top wiper support 45 may also be rigid, and may also provide support to piston cup 44. As used herein, components of piston 20 are said to be rigid if the material that the components are made of has a stiffness (i.e., modulus of elasticity) that is at least twice that of the material that piston cup 44 is made of.

Flapper 46, in this embodiment, has an outside diameter that is less than the outside diameter of piston cup 44, less than the inside diameter of main cylinder 15, and may be less than the outside diameter of bottom wiper support 43, top wiper support 45, or both. In this embodiment, Flapper 46 has a diameter that is sufficiently small to allow drywall mud to flow between flapper 46 and the inside surface of main cylinder 15, for example, when piston 20 is traveling downward (e.g., away from pump head 14). In the embodiment illustrated, flapper 46 is rigid. In other embodiments, flapper 46 may be flexible. In some embodiments, flapper 46 (or an alternative flapper) may bend or pivot out of the way of the flow of drywall mud when piston 20 is traveling downward, for example. In some embodiments, a flapper or component analogous to flapper 46 may be made of two or more pieces, which may be different materials and may have different stiffnesses.

In a number of embodiments, piston 20 includes an (e.g., at least one) elongated hole that receives second end 22 of rod 13. Such an elongated hole may allow second end 22 of rod 13 to move laterally relative to piston 20, for example. As used herein, “laterally” means in a direction that is substantially perpendicular to the longitudinal axis of rod 13. As used herein, “substantially perpendicular”, unless stated otherwise, means 90 degrees, plus or minus 30 degrees, and “perpendicular” (without being preceded by “substantially”), unless stated otherwise, means 90 degrees, plus or minus 5 degrees.

In the embodiment illustrated, piston cup 44 of piston 20 has a first elongated hole 44h, top support 45 has a second elongated hole 45h, bottom support 43 has a third elongated hole 43h, and flapper 46 has a fourth elongated hole 46h. In the embodiment shown, when drywall mud pump 10 is assembled, second end 22 of rod 13 passes through each of the first, second, third, and fourth elongated holes (i.e., 43h, 44h, 45h, and 46h). Further, the embodiment illustrated includes a means for preventing piston 20 from rotating about rod 13. Specifically, in the embodiment illustrated, second end 22 of rod 13 has first and second flattened portions 49 and 48, which, in this embodiment, each have a reduced diameter from the remainder of rod 13. In this embodiment, the second and third elongated holes (i.e., holes 45hand 43hin top and bottom supports 45 and 43) are substantially the same size and have substantially same shape, and, when drywall mud pump 10 is assembled, are held in a particular orientation by second flattened portion 48 of second end 22 of rod 13.

As used herein, “substantially the same”, when referring to a dimension, unless stated otherwise, means the same to within 10 percent. In addition, as used herein “held in a particular orientation” when referring to a piston or part of a piston, means that the piston or part is prevented from rotating about the longitudinal axis of the rod by more than 45 degrees. In some embodiments, first hole 44hmay also have substantially the same size and shape as holes 43hand 45h. In other embodiments, first hole 44hmay have a different shape. In certain embodiments, for example, first hole 44h, or a corresponding hole in the piston cup, may be round, may be larger than third hole 43hor second hole 45h, or both. Further, in a number of embodiments, different components of the piston (e.g., components 43-46 of piston 20) may have elongated holes, while in other embodiments, an elongated hole may appear only in one component of the piston, or in one of the top and bottom supports, for example, to hold the piston in a particular orientation with a flattened portion of the second end of the rod. In some embodiments, for example, the third hole 43hin bottom support 43 may be round, may be larger than the second hole 45hin top support 45, or both, and in other embodiments, second hole 45hmay be round, may be larger than third hole 43h, or both.

In the embodiment illustrated, second reduced diameter flattened section 48 has a smaller diameter and thickness between flats than first reduced diameter flattened section 49. Other embodiments may have different sections that just have different diameters or different thicknesses between flats. Further, in the embodiment shown, second end 22 of rod 13 also includes threaded section 47, which in this embodiment, receives nut 41. Further still, when drywall mud pump 10 is assembled, second end 22 of rod 13 passes through each of first, second, third, and fourth elongated holes 43h-46hsuch that fourth elongated hole 46his located at first reduced diameter flattened section 49, and first, second and third elongated holes 43h-45hare located at second reduced diameter flattened section 48.

In the embodiment shown, flattened portion 49 has a sufficient dimension in the axial direction (i.e., of the longitudinal axis of rod 13) to allow flapper 46 to move away from top support 45 when piston 20 is traveling downward away from pump head 14. This allows room for the drywall mud to flow outward between flapper 46 and top support 45 before flowing around the outside of flapper 46. When piston 20 travels in upward, toward pump head 14, flapper 46 moves in the axial direction to the other end of flattened portion 49 until flapper 46 makes contact with top support 45.

In some embodiments, there is a connection structure between the piston (e.g., 20) and second end (e.g., 22) of the rod (e.g., 13) that is configured to allow the second end (e.g., 22) of the rod (e.g., 13) to move relative to the piston (e.g., 20) in a direction that is substantially perpendicular to the axis of the rod (e.g., rod 13). The elongated hole or holes (e.g., 43h, 44h, 45h, 46h, or a combination thereof) through which second end 22 of rod 13 passes, is an example of such a connection structure. Further, a number of embodiments, including the embodiment illustrated, include a means for allowing the second end (e.g., 22) of the rod (e.g., 13) to move laterally relative to the piston (e.g., 20) within the main cylinder (e.g., 15). Other embodiments, besides what is shown in the drawings, may differ in geometry. For example, some embodiments may use a slot or hole in the rod, a pin, a track, a linkage, or the like.

As used herein, a means for allowing an end of a rod to move laterally relative to a piston does not include motion resulting from prior art magnitude clearance between the rod and the piston in a drywall mud pump, movement resulting from deformation of an elastomeric piston cup, or deformation of the rod or other components resulting from stress imposed thereon. Rather, a means for allowing an end of a rod to move laterally relative to a piston requires a structure that provides for substantially more lateral movement of the rod under substantially less force than prior art mud pump technology provided. In this context, as used herein, “substantially” means by a factor of at least two.

In different embodiments, the second end 22 of rod 13 may be able to move laterally relative to piston 20 by at least or about 1/16, ⅛, 3/16, ¼, 5/16, ⅜, 7/16, ½, 9/16, ⅝, ¼, ⅞, 1, 1⅛, 1¼, or 1½, inch, or 2 inches, for example, under lateral forces normally present within such a drywall mud pump. In the embodiment illustrated, the elongated hole (e.g., 43h) in piston 20 is centered within piston 20. But in other embodiments, the elongated hole may extend from the center of piston 20 in one direction, or may extend farther on one side of center than the other, as examples.

In the embodiment illustrated, nut 41 does not clamp down on bottom support 43, piston cup 44, and top support 45. Rather, sufficient clearance is left between nut 41 and support 43, piston cup 44, and top support 45 to allow them to move freely in the lateral direction across elongated holes 43h-45h. The axial dimension of flattened portion 48 may be sized accordingly. In some embodiments, where nut 41 is a lock nut, for example, nut 41 may be turned until the correct amount of clearance is obtained. In other embodiments, nut 41 may be tightened against the end of threaded portion 47, as another example.

FIG. 5 is a detailed view of the same embodiment of bottom support 43. Bottom support 43 includes elongated hole 43hwhich has round ends (i.e., part of a circle). Bottom support 43 includes round holes 51 which receive projections 44p(shown in FIG. 4) of piston cup 44. Projections 44pmay have an interference fit with holes 51, in this embodiment, and may help to hold piston cup 44 in place (e.g., held in the appropriate particular orientation) relative to bottom support 43. In the embodiment shown, bottom support 43 also includes tabs 52 which also help to hold piston cup 44, top support 45, or both in place (e.g., held in the appropriate particular orientation) relative to bottom support 43. The embodiment illustrated includes four tabs 52, although only one of tabs 52 is labeled with a reference number, the one that is the most visible from the perspective of FIG. 5.

Bottom support 43 also includes multiple passageways 53, 54, 55, and 56 therethrough for passage of drywall mud. These passageways 53, 54, 55, and 56 substantially surround (third) elongated hole 43h. As shown in FIG. 4, in the embodiment illustrated, corresponding passageways having substantially the same shape extend through piston cup 44 and top support 45 and substantially surround (first and second) holes 44hand 45h, as well. Drywall mud flows through these passageways (e.g., 53-56), between top support 45 and flapper 46, and around the outside of flapper 46 (i.e., between flapper 46 and the inside of main cylinder 15) when piston 20 is moving downward (i.e., away from pump head 14).

Still referring to FIG. 5, in the embodiment illustrated, all four of the multiple passageways 53, 54, 55, and 56 for passage of drywall mud have at least one curved side 57 and at least one straight side 58, as labeled, for example, for passageway 56. In the embodiment illustrated, the shape of passageways 53, 54, 55, and 56 provides for essentially as much area for the flow of drywall mud therethrough as possible, while maintaining adequate structural strength of the components (e.g., bottom support 43, piston cup 44, etc.).

As mentioned, when piston 20 is traveling upward (i.e., toward pump head 14) in cylinder 15, flapper 46 makes contact with top support 45, blocking or substantially blocking passageways 53, 54, 55, and 56, thus preventing significant quantities of the drywall mud from flowing back through passageways 53, 54, 55, and 56. As used herein, in the context of blocking the flow of drywall mud, “substantially blocking” means blocking more than 90 percent of the cross sectional area (e.g., of passageways 53, 54, 55, and 56), and “blocking” (i.e., without being preceded by “substantially”) means blocking more than 99 percent of the cross sectional area (e.g., of passageways 53, 54, 55, and 56). Blocking or substantially blocking of passageways 53, 54, 55, and 56, in the embodiment illustrated, causes the drywall mud within cylinder 15 to exit through pump head 14 and orifice 11 when piston 20 travels upward (i.e., toward pump head 14).

Further, as shown for example in FIG. 3, in the embodiment illustrated, when drywall mud pump 10 is assembled, washer 42 blocks or substantially blocks the elongated hole (e.g., 43h, 44h, 45h, and 46h) in piston 20 to prevent drywall mud from passing through the elongated hole in piston 20 (e.g., when piston 20 is moving upward toward pump head 14). In a number of such embodiments, the drywall mud pump (e.g., 10), piston (e.g., 20), or rod (e.g., 13) may also include a means for controlling the orientation or rotational position (i.e., about the longitudinal axis of rod 13) of the washer (e.g., 42). This may facilitate washer 42 blocking or substantially blocking the elongated hole (e.g., 43h).

FIG. 6 illustrates piston 20, rod 13, pump head 14, and shortened guide 17, all assembled. In this view, flapper 46 is shown against upper guide 45 (not visible) blocking or substantially blocking passageways 53, 54, 55, and 56, as would be the case when piston 20 is moving toward pump head 14. FIG. 7 shows these same components of drywall mud pump 10 in an exploded view, except that piston 20 is not separated into components or separated from rod 13. FIG. 7 shows, among other things, that below guide 17 is a wiper or rod seal 77, which may be made of an elastomeric material or synthetic rubber, for example, and may serve to prevent or substantially prevent drywall mud from within main cylinder or pump head 14 from traveling up along rod 13 through guide 17. Rod seal 77 may have a U-shaped cross section, for example, with the opening of the U pointed downward (i.e., toward piston 20). In other embodiments, rod seal 77 may have a cross section that is square, rectangular, triangular, trapezoidal, a parallelogram, or round, as examples, and may be solid or hollow.

FIGS. 8 and 9 illustrate more detail of the example of guide 17 of the embodiment illustrated. Guide 17, in this embodiment, includes hole 80hthrough which rod 13 passes when drywall mud pump 10 is assembled. Some embodiments may include (e.g., in pump head 14) a means for guiding rod 13, a means for allowing rod 13 to pivot (e.g., without binding) as second end 22 of rod 13 moves laterally relative to piston 20, or both. In the embodiment illustrated, guide 17 is a shortened guide, and rod 13 slidably passes through hole 80hwhen pump 10 is assembled. Prior art guides for drywall mud pumps typically have a gland nut with a dimension 90t(shown in FIG. 9) in the direction of the longitudinal axis of rod 13 that is ¾ inch or more. In the embodiment illustrated, guide 17 has a dimension 90tof 0.300 inches. Other embodiments may have a dimension 90tthat is more than ⅛, 3/16, or ¼ inch, and less than ½, ⅜ or 5/16 inch, or the like, as examples. As used herein, a “shortened guide” has a dimension 90tthat is less than ½ inch.

Prior art gland nuts, which served as guides, typically included a recess within the gland nut for a bushing or liner that provided a sliding surface for the rod. This liner often consisted of a non-metal, such as nylon. Shortened guide 17, in the embodiment illustrated, however, does not include a recess for a bushing or liner, and in fact, no such liner is used in the embodiment shown. Rather, rod 13 slides directly on guide 17. Other embodiments may include a bushing or liner within a guide or gland nut, but may provide another means for allowing the rod to pivot (e.g., without binding) as the (second) end of the rod moves laterally relative to the piston. In some embodiments, for example, a bushing or liner may be provided that is made of or includes nylon, PTFE, or the like. In some embodiments in which the gland nut or guide is not shortened, for example, the guide may have a larger diameter or an elongated hole (e.g., 80h) therethrough. In other embodiments, a structure may be provided to allow the guide to pivot, as another example.

In some embodiments, guide 17 serves both as a guide and as a pivot point for rod 13. In some such embodiments, the outside diameter of rod 13 and the inside diameter of hole 80hare selected to provide sufficient clearance between rod 13 and hole 80hto allow second end 22 of rod 13 to move laterally over, for instance, the full range of the elongated hole (e.g., 43h, 44h, 45h, 46h, or a combination thereof) in piston 20 without causing binding between rod 13 and hole 80h, for example, within guide 17. Further, in the prior art, upper and lower guides were used at the top and bottom of the pump head (e.g., otherwise similar to pump head 14). This provided little opportunity for the rod (e.g., similar to rod 13) to pivot in the pump head, and (as used herein) no means for allowing the rod to pivot as the second end of the rod moves laterally relative to the piston. In the embodiment shown, only one (i.e., a single) guide (17) is provided, and guide 17 is shortened, which (as used herein), if sized or shaped in certain ways, may provide a means for allowing rod 13 to pivot without binding as second end 22 of rod 13 moves laterally relative to piston 20.

In some embodiments, hole 80his manufactured as a right circular cylinder (e.g., a drilled hole), but quickly “wears in” when in use, to a shape that is elongated, for instance, with the most pronounced elongation at the top or bottom surface (or both) of guide 17. In some such embodiments, guide 17 is made of a relatively soft material, such as brass, and rod 13 is made of a harder material, such as stainless steel, which may be grade 420 stainless steel, and may be hardened to 35 Rockwell C (HRC), for example. In particular embodiments, rod 13 has an outside diameter of 0.626±0.005 inches, and hole 80hin guide 17 has an inside diameter of 0.640±0.003 inches, for instance. In various such embodiments, friction in the operation of pump 10 may be greater when pump 10 is new, but may decrease once guide 17 wears in and binding between guide 17 and rod 13 declines or ceases. Such a shortened guide 17 that is configured to “wear in” to a shape that does not bind against rod 13, as used herein, is another example of a means for allowing rod 13 to pivot as second end 22 of rod 13 moves laterally relative to piston 20.

In the embodiment illustrated, once guide 17 wears in, and binding between guide 17 and rod 13 declines or ceases, the rate at which guide 17 wears may decrease substantially. However, in cases of frequent use of pump 10, guide 17 may continue to wear over time with continued use. At some point, guide 17 may be replaced. In the embodiment shown, guide 17 and seal 77 are easily replaceable by removing pin 23 and bolts 27.

TECHNICAL FIELD OF THE INVENTION The present invention relates generally to piston seals for mud pumps and more particularly to a replaceable piston seal. Still more particularly, the present invention relates to a durable polymeric piston seal constructed with very small tolerances so as to provide a precise interference fit with the corresponding liner.

Slush or mud pumps are commonly used for pumping drilling mud in connection with oil well drilling operations. Because of the need to pump the drilling mud through several thousand feet of drill pipe, such pumps typically operate at high pressures. Moreover, it is necessary for the mud to emerge from the drill bit downhole at a relatively high velocity in order to provide lubrication and cooling to the bit and to provide a vehicle for the removal of drill cuttings from the earth formation being drilled. Lastly, the pressure generated by the mud pump contributes to the total downhole pressure, which is used to prevent well blowouts.

The pistons and cylinders used for such mud pumps are susceptible to a high degree of wear during use because the drilling mud is relatively dense and has a high proportion of suspended abrasive solids. As the pump cylinder becomes worn, the small annular space between the piston and the cylinder wall increases substantially and sometimes irregularly. For these reasons, the seal design for such pumps is critical.

The high pressure abrasive environment in which the pumps must operate is especially deleterious to the seals since considerable friction forces are generated, and since the hydraulic pressures encountered during operation force the seal into the annular space between the cylinder wall and the piston. In some instances, the frictional forces may even detach the seal from the piston. In these instances, the edges of the seal can become damaged very quickly by the cutting or tearing action that occurs as a result of piston movement. Another problem with conventional mud pump seals is that they do not adequately "wipe" the

Attempts have been made to retain the seal in the piston so as to resist this frictional force. One conventional solution to this problem has been use of a metallic seal retainer which is disposed over the seal body and retained in place by snap rings. One disadvantage of this solution, however, is that the additional seal retaining element and its snap rings render the overall piston construction more expensive. A further disadvantage is that the seal is made somewhat less flexible and resilient than it would otherwise be, thus decreasing its ability to wipe the cylinder wall effectively. Another conventional solution to the sealing problem comprises including a seal retaining ring or reinforcement in the seal itself. In this case, the retaining ring or reinforcement is molded into the seal material. As with the external retaining ring, this solution decreases the flexibility of the seal and increases its cost of manufacture.

It is common to incorporate the foregoing seals into piston heads wherein the seal is permanently affixed to the piston head. This is disadvantageous because the seal tends to wear much faster than the piston head, resulting in waste and unnecessary expense when the whole piston head has to be replaced because of wear to the seal member. It is therefore desirable to provide a piston seal that is removable from the piston head and thus can be replaced without requiring replacement of the whole piston head. The nature of the mud pump operating environment makes it difficult to effectively address these issues. It is, therefore, desired to develop a new and improved replaceable seal for a reciprocating mud pump piston that overcomes the foregoing difficulties while providing better wear properties and more advantageous overall results.

BRIEF SUMMARY OF THE INVENTION The present invention comprises a new and improved replaceable seal for a reciprocating mud pump piston. The present seal does not require any external seal retaining means and is free from any incorporated seal retainer or reinforcement. The present seal is manufactured to precise specifications that minimize play between the seal, piston head and cylinder and also compensate for the slight deformation of the seal member that occurs when the seal member is demolded and cured.

Figure 3 is a cross sectional view of the sealing member of Figure 2 mounted on a piston head in a cylinder. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring initially to Figure 1, a typical prior-art mud pump piston assembly comprises a piston head 10 and a sealing device or seal 15 therefor slidably received in a piston cylinder 12. Piston head 10 comprises a generally cylindrical body having a flange 11 extending therefrom. Piston head 10 is typically made of steel, such as AISI 4140. Seal 15 is friction fit on piston head 10 and abuts flange 11. Seal 15 comprises an elastomeric sealing section 14 and a heel section 13. These sections are either integrally formed or bonded together. Heel section 13 is typically made from a stack of several layers of rubber- impregnated fabric, which give it a higher modulus of elasticity than the elastomeric sealing section 14. In prior art mud pumps, the heel section 13, which is stiffer than the elastomeric sealing section, resists extrusion into the gap between the cylinder and piston flange to some extent. However, heel section 13 is still forced into the gap under the influence of the hydrostatic pressure in locations where wear occurs. Reference numeral 18 designates a portion of heel section 14 that has been extruded into the gap 20 between the flange 11 and the cylinder 12. Both elastomeric sealing section 14 and heel section 13 make intimate contact with the cylinder 12. Seal 15 is held in place by a retaining ring 16 and a snap ring 17, which hold seal 15 in place and permit replacement thereof. Easy replacement of seals is a desirable feature for a mud pump, since seals typically wear out long before the other mud pump components and must be replaced in order to continue pumping operations. The direction of travel of piston 10 is shown by arrow 19. The direction of the hydrostatic pressure force exerted by the working fluid of the pump is shown by arrows 21. This force axially compresses elastomeric sealing section 14 and heel section 13 and radially expands these sections against the cylinder wall.

Referring now to Figure 3, the seal 22 of Figure 2 is shown mounted on a piston head in a cylinder. It can be seen that sealing lip 24 is compressed radially and conforms to the inside of 12. In addition, in order to enable seal 22 to be used without a reinforced heel section, piston head 10 is manufactured to extremely tight tolerances. In particular, it has been discovered that the life of seal 22 can be greatly prolonged by ensuring that play between flange 11 and cylinder 12 is minimized at the outset. Thus, the average width of the annular gap 25 between flange 11 and cylinder 12 is much smaller than in previously known devices. In this regard, it is preferred that the difference between the outside diameter of flange 11 as manufactured and the inside diameter of cylinder 12 as manufactured be less than 0.010 inches, and more preferably less than 0.008 inches. By way of example, flange 11 of a 6 inch piston is preferably about 0.002 to 0.010 inch smaller than the associated bore.

As can be seen in the Figures, the sealing lip 24 of seal 22 is preferably somewhat larger than the nominal inside diameter of the cylinder 12. Again by way of example, for a piston having a nominal diameter of six inches, sealing lip 24 preferably has a diameter of about 6.25 inches. Thus, in one preferred embodiment, diameters are as follows: for metal flange 11, df = 5.990; for cylinder 12, inside diameter idi = 6.000; for seal lip 23, ds = 6.250; and for heel 24, dh = 5.990.

Although the invention is described with particular reference to a pump piston used with slush or mud pumps, it will be recognized that certain features thereof may be used or adopted to use in other types of reciprocating pumps. Likewise it will be understood that various modification can be made to the present seal without departing from the scope of the invention. For example, the relative dimensions of various parts, the materials from which the seal is made, and other parameters can be varied, so long as the seal retains the advantages discussed herein.

Mechanical pumps serve in a wide range of applications such as pumping water from wells, aquarium filtering, pond filtering and aeration, in the car industry for water-cooling and fuel injection, in the energy industry for pumping oil and natural gas or for operating cooling towers and other components of heating, ventilation and air conditioning systems. In the medical industry, pumps are used for biochemical processes in developing and manufacturing medicine, and as artificial replacements for body parts, in particular the artificial heart and penile prosthesis.

When a pump contains two or more pump mechanisms with fluid being directed to flow through them in series, it is called a multi-stage pump. Terms such as two-stage or double-stage may be used to specifically describe the number of stages. A pump that does not fit this description is simply a single-stage pump in contrast.

In biology, many different types of chemical and biomechanical pumps have evolved; biomimicry is sometimes used in developing new types of mechanical pumps.

Pumps can be classified by their method of displacement into positive-displacement pumps, impulse pumps, velocity pumps, gravity pumps, steam pumps and valveless pumps. There are three basic types of pumps: positive-displacement, centrifugal and axial-flow pumps. In centrifugal pumps the direction of flow of the fluid changes by ninety degrees as it flows over an impeller, while in axial flow pumps the direction of flow is unchanged.

Some positive-displacement pumps use an expanding cavity on the suction side and a decreasing cavity on the discharge side. Liquid flows into the pump as the cavity on the suction side expands and the liquid flows out of the discharge as the cavity collapses. The volume is constant through each cycle of operation.

Positive-displacement pumps, unlike centrifugal, can theoretically produce the same flow at a given speed (rpm) no matter what the discharge pressure. Thus, positive-displacement pumps are constant flow machines. However, a slight increase in internal leakage as the pressure increases prevents a truly constant flow rate.

A positive-displacement pump must not operate against a closed valve on the discharge side of the pump, because it has no shutoff head like centrifugal pumps. A positive-displacement pump operating against a closed discharge valve continues to produce flow and the pressure in the discharge line increases until the line bursts, the pump is severely damaged, or both.

A relief or safety valve on the discharge side of the positive-displacement pump is therefore necessary. The relief valve can be internal or external. The pump manufacturer normally has the option to supply internal relief or safety valves. The internal valve is usually used only as a safety precaution. An external relief valve in the discharge line, with a return line back to the suction line or supply tank provides increased safety.

Rotary-type positive displacement: internal or external gear pump, screw pump, lobe pump, shuttle block, flexible vane or sliding vane, circumferential piston, flexible impeller, helical twisted roots (e.g. the Wendelkolben pump) or liquid-ring pumps

Drawbacks: The nature of the pump requires very close clearances between the rotating pump and the outer edge, making it rotate at a slow, steady speed. If rotary pumps are operated at high speeds, the fluids cause erosion, which eventually causes enlarged clearances that liquid can pass through, which reduces efficiency.

Hollow disk pumps (also known as eccentric disc pumps or Hollow rotary disc pumps), similar to scroll compressors, these have a cylindrical rotor encased in a circular housing. As the rotor orbits and rotates to some degree, it traps fluid between the rotor and the casing, drawing the fluid through the pump. It is used for highly viscous fluids like petroleum-derived products, and it can also support high pressures of up to 290 psi.

Vibratory pumps or vibration pumps are similar to linear compressors, having the same operating principle. They work by using a spring-loaded piston with an electromagnet connected to AC current through a diode. The spring-loaded piston is the only moving part, and it is placed in the center of the electromagnet. During the positive cycle of the AC current, the diode allows energy to pass through the electromagnet, generating a magnetic field that moves the piston backwards, compressing the spring, and generating suction. During the negative cycle of the AC current, the diode blocks current flow to the electromagnet, letting the spring uncompress, moving the piston forward, and pumping the fluid and generating pressure, like a reciprocating pump. Due to its low cost, it is widely used in inexpensive espresso machines. However, vibratory pumps cannot be operated for more than one minute, as they generate large amounts of heat. Linear compressors do not have this problem, as they can be cooled by the working fluid (which is often a refrigerant).

Reciprocating pumps move the fluid using one or more oscillating pistons, plungers, or membranes (diaphragms), while valves restrict fluid motion to the desired direction. In order for suction to take place, the pump must first pull the plunger in an outward motion to decrease pressure in the chamber. Once the plunger pushes back, it will increase the chamber pressure and the inward pressure of the plunger will then open the discharge valve and release the fluid into the delivery pipe at constant flow rate and increased pressure.

Pumps in this category range from simplex, with one cylinder, to in some cases quad (four) cylinders, or more. Many reciprocating-type pumps are duplex (two) or triplex (three) cylinder. They can be either single-acting with suction during one direction of piston motion and discharge on the other, or double-acting with suction and discharge in both directions. The pumps can be powered manually, by air or steam, or by a belt driven by an engine. This type of pump was used extensively in the 19th century—in the early days of steam propulsion—as boiler feed water pumps. Now reciprocating pumps typically pump highly viscous fluids like concrete and heavy oils, and serve in special applications that demand low flow rates against high resistance. Reciprocating hand pumps were widely used to pump water from wells. Common bicycle pumps and foot pumps for inflation use reciprocating action.

These positive-displacement pumps have an expanding cavity on the suction side and a decreasing cavity on the discharge side. Liquid flows into the pumps as the cavity on the suction side expands and the liquid flows out of the discharge as the cavity collapses. The volume is constant given each cycle of operation and the pump"s volumetric efficiency can be achieved through routine maintenance and inspection of its valves.

This is the simplest form of rotary positive-displacement pumps. It consists of two meshed gears that rotate in a closely fitted casing. The tooth spaces trap fluid and force it around the outer periphery. The fluid does not travel back on the meshed part, because the teeth mesh closely in the center. Gear pumps see wide use in car engine oil pumps and in various hydraulic power packs.

A screw pump is a more complicated type of rotary pump that uses two or three screws with opposing thread — e.g., one screw turns clockwise and the other counterclockwise. The screws are mounted on parallel shafts that have gears that mesh so the shafts turn together and everything stays in place. The screws turn on the shafts and drive fluid through the pump. As with other forms of rotary pumps, the clearance between moving parts and the pump"s casing is minimal.

Widely used for pumping difficult materials, such as sewage sludge contaminated with large particles, a progressing cavity pump consists of a helical rotor, about ten times as long as its width. This can be visualized as a central core of diameter x with, typically, a curved spiral wound around of thickness half x, though in reality it is manufactured in a single casting. This shaft fits inside a heavy-duty rubber sleeve, of wall thickness also typically x. As the shaft rotates, the rotor gradually forces fluid up the rubber sleeve. Such pumps can develop very high pressure at low volumes.

Named after the Roots brothers who invented it, this lobe pump displaces the fluid trapped between two long helical rotors, each fitted into the other when perpendicular at 90°, rotating inside a triangular shaped sealing line configuration, both at the point of suction and at the point of discharge. This design produces a continuous flow with equal volume and no vortex. It can work at low pulsation rates, and offers gentle performance that some applications require.

A peristaltic pump is a type of positive-displacement pump. It contains fluid within a flexible tube fitted inside a circular pump casing (though linear peristaltic pumps have been made). A number of rollers, shoes, or wipers attached to a rotor compresses the flexible tube. As the rotor turns, the part of the tube under compression closes (or occludes), forcing the fluid through the tube. Additionally, when the tube opens to its natural state after the passing of the cam it draws (restitution) fluid into the pump. This process is called peristalsis and is used in many biological systems such as the gastrointestinal tract.

Efficiency and common problems: With only one cylinder in plunger pumps, the fluid flow varies between maximum flow when the plunger moves through the middle positions, and zero flow when the plunger is at the end positions. A lot of energy is wasted when the fluid is accelerated in the piping system. Vibration and

Triplex plunger pumps use three plungers, which reduces the pulsation of single reciprocating plunger pumps. Adding a pulsation dampener on the pump outlet can further smooth the pump ripple, or ripple graph of a pump transducer. The dynamic relationship of the high-pressure fluid and plunger generally requires high-quality plunger seals. Plunger pumps with a larger number of plungers have the benefit of increased flow, or smoother flow without a pulsation damper. The increase in moving parts and crankshaft load is one drawback.

Car washes often use these triplex-style plunger pumps (perhaps without pulsation dampers). In 1968, William Bruggeman reduced the size of the triplex pump and increased the lifespan so that car washes could use equipment with smaller footprints. Durable high-pressure seals, low-pressure seals and oil seals, hardened crankshafts, hardened connecting rods, thick ceramic plungers and heavier duty ball and roller bearings improve reliability in triplex pumps. Triplex pumps now are in a myriad of markets across the world.

Triplex pumps with shorter lifetimes are commonplace to the home user. A person who uses a home pressure washer for 10 hours a year may be satisfied with a pump that lasts 100 hours between rebuilds. Industrial-grade or continuous duty triplex pumps on the other end of the quality spectrum may run for as much as 2,080 hours a year.

The oil and gas drilling industry uses massive semi trailer-transported triplex pumps called mud pumps to pump drilling mud, which cools the drill bit and carries the cuttings back to the surface.

One modern application of positive-displacement pumps is compressed-air-powered double-diaphragm pumps. Run on compressed air, these pumps are intrinsically safe by design, although all manufacturers offer ATEX certified models to comply with industry regulation. These pumps are relatively inexpensive and can perform a wide variety of duties, from pumping water out of bunds to pumping hydrochloric acid from secure storage (dependent on how the pump is manufactured – elastomers / body construction). These double-diaphragm pumps can handle viscous fluids and abrasive materials with a gentle pumping process ideal for transporting shear-sensitive media.

Devised in China as chain pumps over 1000 years ago, these pumps can be made from very simple materials: A rope, a wheel and a pipe are sufficient to make a simple rope pump. Rope pump efficiency has been studied by grassroots organizations and the techniques for making and running them have been continuously improved.

Impulse pumps use pressure created by gas (usually air). In some impulse pumps the gas trapped in the liquid (usually water), is released and accumulated somewhere in the pump, creating a pressure that can push part of the liquid upwards.

Instead of a gas accumulation and releasing cycle, the pressure can be created by burning of hydrocarbons. Such combustion driven pumps directly transmit the impulse from a combustion event through the actuation membrane to the pump fluid. In order to allow this direct transmission, the pump needs to be almost entirely made of an elastomer (e.g. silicone rubber). Hence, the combustion causes the membrane to expand and thereby pumps the fluid out of the adjacent pumping chamber. The first combustion-driven soft pump was developed by ETH Zurich.

It takes in water at relatively low pressure and high flow-rate and outputs water at a higher hydraulic-head and lower flow-rate. The device uses the water hammer effect to develop pressure that lifts a portion of the input water that powers the pump to a point higher than where the water started.

The hydraulic ram is sometimes used in remote areas, where there is both a source of low-head hydropower, and a need for pumping water to a destination higher in elevation than the source. In this situation, the ram is often useful, since it requires no outside source of power other than the kinetic energy of flowing water.

Rotodynamic pumps (or dynamic pumps) are a type of velocity pump in which kinetic energy is added to the fluid by increasing the flow velocity. This increase in energy is converted to a gain in potential energy (pressure) when the velocity is reduced prior to or as the flow exits the pump into the discharge pipe. This conversion of kinetic energy to pressure is explained by the

A practical difference between dynamic and positive-displacement pumps is how they operate under closed valve conditions. Positive-displacement pumps physically displace fluid, so closing a valve downstream of a positive-displacement pump produces a continual pressure build up that can cause mechanical failure of pipeline or pump. Dynamic pumps differ in that they can be safely operated under closed valve conditions (for short periods of time).

Such a pump is also referred to as a centrifugal pump. The fluid enters along the axis or center, is accelerated by the impeller and exits at right angles to the shaft (radially); an example is the centrifugal fan, which is commonly used to implement a vacuum cleaner. Another type of radial-flow pump is a vortex pump. The liquid in them moves in tangential direction around the working wheel. The conversion from the mechanical energy of motor into the potential energy of flow comes by means of multiple whirls, which are excited by the impeller in the working channel of the pump. Generally, a radial-flow pump operates at higher pressures and lower flow rates than an axial- or a mixed-flow pump.

These are also referred to as All fluid pumps. The fluid is pushed outward or inward to move fluid axially. They operate at much lower pressures and higher flow rates than radial-flow (centrifugal) pumps. Axial-flow pumps cannot be run up to speed without special precaution. If at a low flow rate, the total head rise and high torque associated with this pipe would mean that the starting torque would have to become a function of acceleration for the whole mass of liquid in the pipe system. If there is a large amount of fluid in the system, accelerate the pump slowly.

Mixed-flow pumps function as a compromise between radial and axial-flow pumps. The fluid experiences both radial acceleration and lift and exits the impeller somewhere between 0 and 90 degrees from the axial direction. As a consequence mixed-flow pumps operate at higher pressures than axial-flow pumps while delivering higher discharges than radial-flow pumps. The exit angle of the flow dictates the pressure head-discharge characteristic in relation to radial and mixed-flow.

Regenerative turbine pump rotor and housing, 1⁄3 horsepower (0.25 kW). 85 millimetres (3.3 in) diameter impeller rotates counter-clockwise. Left: inlet, right: outlet. .4 millimetres (0.016 in) thick vanes on 4 millimetres (0.16 in) centers

Also known as drag, friction, peripheral, traction, turbulence, or vortex pumps, regenerative turbine pumps are class of rotodynamic pump that operates at high head pressures, typically 4–20 bars (4.1–20.4 kgf/cm2; 58–290 psi).

The pump has an impeller with a number of vanes or paddles which spins in a cavity. The suction port and pressure ports are located at the perimeter of the cavity and are isolated by a barrier called a stripper, which allows only the tip channel (fluid between the blades) to recirculate, and forces any fluid in the side channel (fluid in the cavity outside of the blades) through the pressure port. In a regenerative turbine pump, as fluid spirals repeatedly from a vane into the side channel and back to the next vane, kinetic energy is imparted to the periphery,

As regenerative turbine pumps cannot become vapor locked, they are commonly applied to volatile, hot, or cryogenic fluid transport. However, as tolerances are typically tight, they are vulnerable to solids or particles causing jamming or rapid wear. Efficiency is typically low, and pressure and power consumption typically decrease with flow. Additionally, pumping direction can be reversed by reversing direction of spin.

Steam pumps have been for a long time mainly of histor