EP0737284A1

EP0737284A1 - Valve device

Info

Publication number: EP0737284A1
Application number: EP95905828A
Authority: EP
Inventors: Karl-Olof Sandgren; Fred MÖLLER
Original assignee: Tetra Laval Holdings and Finance SA
Current assignee: DeLaval International AB
Priority date: 1993-12-30
Filing date: 1994-12-23
Publication date: 1996-10-16
Also published as: SE9304335D0; CA2179429A1; WO1995018323A1; AU1428995A

Abstract

An apparatus has a channel (5) for a fluid and a member (8) adapted to accomplish a first throughflow area in a first position in the channel and a second throughflow area in a second position in the channel. The member (8) is adjustable for accomplishing a third throughflow area, which is different from the first throughflow area, when the member is in the first position. Alternatively, the apparatus consists of a set of parts comprising three interchangeable members, for achieving different throughflow areas in the channel. A milking equipment (20) has a pulsator (27) adapted to communicate with the pulsation space in each teatcup via an apparatus (D) of the above described kind.

Description


  
 



  Valve device
The present invention relates to an apparatus comprising a housing forming a channel for a reciprocating fluid, and a member arranged in the channel and adapted to accomplish a first throughflow area in a first position, for said fluid and to accomplish a second throughflow area in a second position for said fluid in the channel.



  Such an apparatus is known from SE-B-373 727.



  The invention also relates to an apparatus comprising a housing forming a channel for a reciprocating fluid and a member arranged freely movable in the channel between a first and a second position in the channel, without stopping the fluid flow. Such an apparatus is known from
SE-A-8602678-8.



  SE-B-373 727 describes a valve device intended to be placed in a teat liner for a milking machine for preventing resplashing of milk in the teat liner, which may cause pains in the cow's teat. When the valve device is closed there is a possibility for a certain reflow of the milk through a passage in the valve. In this way the said first throughflow area is achieved. When the valve is open said second throughflow area is achieved.



  SE-A-8602678-8 describes a pulsation indicator intended to be arranged in a pulsation tube between a pulsator and a teatcup in a milking machine. The pulsation indicator comprises a ball in an elongated, transparent housing. During operation, when the pulsator alternates between normally underpressure and the atmospheric pressure, the pressure alternation can be checked by observing the movement of the ball back and forth in the transparent housing.  



  CH-A-508 144 discloses a valve for achieving different flow resistances in opposing directions of a flow of a liquid. In two of the four disclosed embodiments, a valve member is formed as a ball having a density lower than the liquid, whereas in the two other embodiments, the valve member is formed as a movable flap. Two different throughflow areas are possible to achieve in each of the four embodiments.



  US-A-3 138 177 discloses a flow control device for drinking fountains, lavatories, washing machines or the like, having a liquid flow in one direction. The liquid flow is rendered constant, disregarding the liquid pressure by means of a valve member, which, due to the liquid pressure, is gradually caused to sink into a resilient member to a compressive engagement with one another.



  US-A-631 036 discloses a check valve for preventing the flow of a fluid from taking a direction opposite to a single desired flow direction. To reverse the valve, a valve member is turned instead of turning a whole valve housing.



  A conventional milking machine connected to a pneumatic pressure source operates with relatively fast alternations between underpressure and atmospheric pressure alternatively underpressure and overpressure. Research has proven that these quick pressure alternations may be troublesome for certain cows, having sensitive teats.



  According to a method known from WO 92/12625, slower pressure alternations can be accomplished, which substantially reduces said trouble.  



  An object of the present invention is to accomplish a simple apparatus for carrying out said known method.



  Another object of the invention is to accomplish such an apparatus, which can be utilized in a milking machine for milking of differently sensitive cows, i.e. if quick pressure alternations are desired during milking of insensitive cows the apparatus shall also be adjustable for this in an easy way.



  Yet another object of the invention is to obtain such an apparatus, which is adjustable to a plurality of different pressure alternations.



  These objects are accomplished by means of an apparatus of the initially described kind, which is characterized in that the member is adjustable such that it accomplishes a third throughflow area, which is different from the first throughflow area when the member is in the first position. Hereby, a simple adjustment possibility of the pressure alternations is achieved.



  Furthermore these objects are accomplished by an apparatus of the thereafter described kind which is characterized in that the member is adapted to change the throughflow area in the channel when the member is at least in the first position. Hereby, an alternative, simple adjustment possibility of the pressure alternations is achieved.



  Furthermore a possibility of adapting the speed of each pressure alternation to a desired value is achieved.



  Preferably, the first throughflow area is smaller than the second throughflow area, and the third throughflow  area is larger than the first and substantially as large as the second. Hereby, a milking machine which is provided with an apparatus according to the invention may for example be operated such that said pressure alternations comprise relatively slow pressure drops but relatively fast pressure increases or vice versa.



  Suitably, said housing has a transparent portion, whereby the pressure alternations can be indicated by visual observation of the member's movement.



  Advantageously, seatings are provided in the channel, against which seatings the member abuts when it takes said positions, and the member is formed with at least one central passage. Furthermore, it is advantageous to provide the member with at least one peripheral passage, so that a desired throughflow area can be chosen.



  The first throughflow area is formed in a desired case, suitably by the member's central passage when the member abuts the first seating. Furthermore, the second throughflow area is formed by the member's central and peripheral passages when the member abuts the second seating. When the member is in its first position and is adjusted to accomplish said third throughflow area, this is formed by the member's central and peripheral passages.



  Preferably, the housing comprises at least two, releasably interconnected parts, whereby the member is accessible for cleaning and for said adjustment for accomplishing the third throughflow area, which adjustment advantageously is accomplished by turning the member in the channel.  



  Furthermore, said objects are accomplished by an apparatus consisting of a set of parts and comprising a disconnectible housing, which forms a channel for a fluid; three interchangeable members, which are each movable in the channel between a first and a second position; and means adapted to indicate the movement of each member; wherein a first member is adapted to accomplish a first throughflow area in said first position, and to accomplish a second throughflow area in said second position, wherein the first throughflow area is different from the second throughflow area; a second member is adapted to accomplish a reduced first throughflow area in the channel in said first position and to accomplish a reduced second throughflow area in the channel in said second positon, wherein the first throughflow area is substantially as large as the second throughflow area; 

   and wherein a third member is adapted to   accomplish    a substantially unreduced first throughflow area i the channel in said first position and to accomplish a substantially unreduced second throughflow area in the channel in said second position wherein the first throughflow area is substantially as large as the second throughflow area.



  Hereby is achieved an apparatus, which is adjustable to a plurality of desired pressure alternations, having varying flow characteristics.



  The invention will now be described more closely in connection with the annexed drawings, in which  
Figure 1A shows a first embodiment of an apparatus according to the invention with a member in a first position,
Figure 1B shows the same apparatus as figure 1A, but with the member in a second position,
Figure 1C shows a section along the line   lC-lC    in figure 1A,
Figure 1D shows an enlarged view of a longitudinal section through the member in the apparatus according to figures 1A and 1B,
Figure 2A shows the same apparatus as figure 1A, with the member in the first position but with a changed adjustment of the member,
Figure 2B shows the same apparatus and adjustment of the member as figure 2A,

   but with the member in the second position,
Figure 2C shows a section along the line   lIC-lIC    in figure 2A,
Figure 3A shows a second embodiment of an apparatus according to the invention with the same member as in figure 1A,
Figure 3B shows the same apparatus as figure 3B, but with changed adjustment of the member,
Figure 3C shows the same apparatus as figure 3A, but provided with a first modified member,  
Figure 3D shows the same apparatus as figure 3A, but provided with a second modified member,
Figure 4 shows schematically a milking equipment including two apparatuses according to the invention,
Figure 5A shows with a continuous line a normal pulsation curve for a conventional milking machine describing the pressure change in a pulsation chamber of a teatcup with liner,

   and with broken line how an apparatus according to the invention connected to the milking machine influences an introductive phase of the pulsation curve.



  Figure   5B    shows with a continuous line the same normal pulsation curve as figure 5A, and with broken line how an apparatus according to the invention connected to the milking machine influences a finishing phase of the pulsation curve.



  Figure   5C    shows with a continuous line the same normal pulsation curve as figure   5A    and with broken line how an   apparatus according to the invention connected to the    milking machine influences the introductory as well as the finishing phase of the pulsation curve.



  Figure 1A shows a first embodiment of an apparatus D according to the invention comprising a housing 1 with a first part 2 and a second part 3. The first part 2 of the housing is formed as a male member with external threads 4a, which male member forms a throughgoing, first circular cylindrical channel 5. The second part 3 of the housing is formed as a female member which comprises a first portion 3a, forming a throughgoing, second circular cylindrical channel 6, which has the  same diameter as the first channel 5, a second portion 3b forming a third circular cylindrical channel 7 with larger diameter than the second channel 6, and a third portion 3c formed with internal threads 4b.

  The female member receives the male member such that the threads 4b of the third portion engage with the threads 4a of the male member, wherein the second part's channel 7 forms an elongated circular cylindrical chamber. The first channel 5, as well as the second channel 6, discharges coaxially via openings 5a, 6a in the chamber 7.



  Alternatively, other means for connection of the housing's male and the female member may be used, such as a snap joint, a bayonet joint, a ball spring joint, a hose clamp etc.



  An o-ring R or some other suitable sealing means is arranged between the male member 2 and the female member 3 for sealing between the same.



  A member 8 intended to be loosely arranged in the chamber 7 comprises a plate 9 with a substantially circular cross-section, wherein a passage 10 extends centrally through the plate 9. The plate 9 has a smaller diameter than the chamber 7 and is provided with four symmetrically arranged radial protrusions   lla-d    cooperating with the chamber's 7 circumferential wall such that the plate 9 is centered in the chamber 7. Each of the radial protrusions   11a-d    has a first axial protrusion 12 extending from the plate 9 in one direction along the chamber 7, and a second axial protrusion 13, extending from the plate 9 in the opposite direction along the chamber 7. The radial protrusions   lla-d    have the same radial extension from the plate 9.  



  The first axial protrusions 12 are shorter and have less radial extension a seen from the chamber's 7 circumferential wall than the other axial protrusions 13.



  The member 8 can move freely in the chamber 7 between the first throughgoing channel's opening 5a, about which a first seating 14 for the member 8 is formed on the male member 2, and the second throughgoing channel's opening 6a about which a second seating 15 for the member is formed on the female member 3. The chamber's 7 circumferential wall, the plate 9 and the plate's 9 radial protrusions   11a-d    delimit thereby four peripheral passages 16a-d.



  At least the second portion 3b of the housing 1 is transparent, whereby the movement of the member 8 is visually indicatable.



  Of course, the number of radial protrusions   lla-d    do not need to be four, but both more or fewer radial protrusions would be possible to arrange on the plate 9, whereby a varying number of passages are formed depending on the number of radial protrusions. In the same way it would be possible to form the plate 9 such that it gets substantially the same diameter as the chamber 7, i.e. without radial protrusions. Thereby, the axial protrusions 12, 13 are arranged directly on the plate 9 in both axial directions for example in the form of one or several pins or a ring. In this case the plate 9 has to be provided with peripheral recesses to form the necessary passages between the plate 9 and the housing 1.



  Figure 1A and 1B show the member 8 oriented in the chamber 7 such that the shorter, first axial protrusions  12 are closest to the first seating 14, while the longer, second axial protrusions 13 are closest to the second seating 15. As is described above the housing is disconnectible, whereby the member 8 can be turned in the chamber 7 such that the shorter, first axial protrusions 12 are closest to the second seating 15, whereas the longer protrusions 13 are closest to the first seating 14, as shown in figures 2A and 2B.



  The first seating 14 is formed as a circular cylindrical connection piece S on the male member. Between the connection piece S and the chamber's 7 circumferential wall an annular intermediate space 17 is formed, in which the shorter, first axial protrusions 12 with less radial extension a has access (see figure   1A).    However, the second axial protrusions 13 with larger radial extension b do not fit in the intermediate space 17.

 

  The seating 15 of the second throughgoing channel is formed with an annular surface 18, extending radially from the second throughgoing channel's opening 6a towards the periphery of the chamber 7. The axial protrusions 12, 13 are arranged on the plate 9 such that during movement of the member 8 towards the second channel's seating 15 and depending on the member's 8 orientation in the chamber 7, either the shorter axial protrusions 12 or the longer axial protrusions 13 will abut the annular surface 18, which hence acts as a stop member for the further movement of the member 8 (cf. the figures 1B and 2B).



  Figure 3A shows a second embodiment of an apparatus D' according to the invention comprising a housing 1' with a first part 2, a second part 19 and a third part 2', wherein the first part 2 constitutes a first male member  forming a first throughgoing channel 5, the third part 2' constitutes a second male member forming a second throughgoing channel 5' and the second part 19 constitutes a transparent sleeve with two free ends 19a, 19b and forms a double female member. The both male members 2, 2' and the sleeve 19 define a central chamber 7', wherein the first male member 2 and the second male member 2' form   a' first    seating 14 and a second seating 14', respectively, in the central chamber 7'.

  The first male member 2 as well as a first portion 19c of the sleeve, is formed with a righthand thread 4a, 4b, whereas the other male member 2' as well as a second portion of the sleeve 19d is formed with a lefthand thread 4a', 4b'. The sleeve 19 can hereby be taken away from the male member 2, 2' without need for twisting tubes or pipes connected to the male members 2, 2', since the male members 2, 2' only perform a pure translational movement during rotation of the sleeve 19.



  A member 8 of the same kind as has been described in connection with the first embodiment according to figures 1A-2C is intended to be arranged in the chamber 7'.



  The first as well as the second male member's seating 14 and 14', respectively, is provided with a connection piece S and S', respectively. Between the respective connection piece S and S' and the chamber's 7 circumferential wall an annular interspace 17 and 17', respectively, is formed, in which the shorter, first axial protrusion 12 with less radial extension a has access (see figure 3A). However, the second axial protrusion 13 with larger radial extension b does not fit in the  annular interspace 17 and 17', respectively (see figure 3B).



  It is possible to exchange the member 8 by a symmetrical member, which is provided with similar axial protrusions 12, 12'; 13, 13' in both axial directions, i.e. all axial protrusions have either a less radial extension a (see figure 1D and the member 8' in figure 3C) or a larger radial extension b (see figure 1D and the member 8" in figure 3D).



  Figure 4 shows a milking equipment 20 comprising a first, a second, a third and a fourth teatcup 21a-d with shell 22a-d and liner 23a-d, wherein four pulsation spaces formed between the shells and the liners (not shown) are connected by means of four tubings 24a-d to a claw piece 25. The first and the second teatcup   21a,    b are both connected to a first inner partial space 25a of the claw piece 25 while the third and the fourth teatcup   21c,    d are connected to a second inner partial space   25b.    The first and the second partial spaces 25a, b are connected via tubings 26a, b, respectively, to a pulsator 27, which in turn is connected to a vacuum pump 28.



  In the respective tubing 26a, b between the claw piece 25 and the pulsator 27 an apparatus D or D' according to the invention is provided, wherein the first throughgoing channel 5 is connected closest to the pulsator and the second throughgoing channel 6, 5' is connected closest to the claw piece 25. The central passage 10 of the member 8, 8', 8" in each apparatus D, D' has a smaller area than the throughflow area of each tubing 26a, b.  



  With the milking equipment 20 in operation the vacuum pump 28 generates a vacuum in the pulsator 27. The pulsator is adapted to cyclicly first connect the pulsation spaces of the first and the second teatcups 21a, b to vacuum while the pulsation spaces of the third and fourth teatcups 21c, d are connected to the atmosphere. Thereafter, the pulsator shifts such that the pulsation spaces of the third and the fourth teatcups 21c, d are connected to vacuum, while the pulsation spaces of the first and second teatcups 21a, b are connected to the atmosphere.



  The cyclic pressure variation which hereby arises in each pulsation space, is illustrated in the figures 5A-5C, where the phase a shows the generated pressure drop from the atmospheric pressure alternatively the overpressure   P1    to the underpressure P2, when the liner is opened, the phase b shows the desired applied underpressure P2, when the liner is open, the phase c shows the increase of pressure from the underpressure P2 to the atmospheric pressure alternatively the overpressure
P1, when the liner is closed, and the phase d shows the recovery period of the teat when the liner is closed, before the cycle is repeated.



  As mentioned above, it is sometimes desirable to change this pulsation curve especially such that the a- and/or the c-phase gets slower. As a consequence of this the liner will move slower during opening and closing of the interior of the liner. Prolonged a-phase, i.e. slower opening of the interior of the liner, results in that the teat manages better to expand radially and to keep its frictional grip with the liner, whereby the teatcup is prevented from climbing upwards on the teat towards the udder and causing throttling of the teat's milk  conducting interior in the vicinity of the udder. Such a climbing of the teatcup aggravates the milking and gives rise to an increased amount of rest milk. Prolonged c-phase, i.e. slower closing of the liner's interior results in that the teat is treated more leniently by the liner.



  According to the present invention an extended a-phase is achieved by means of the apparatus according to figures   lA-lD    or figure 3A, wherein the first throughgoing channel 5 is provided closest to the pulsator 27 and the other throughgoing channel 6, 5' is provided closest to the claw piece 25. When the pulsator 27 creates a vacuum in the chamber 7 the member 8 is sucked against the first seating, i.e. against the connection piece S with the member's first axial protrusion 12 astraddling the connection piece S such that the plate 9 of the member 8 abuts the connection piece (see figure 1A and 3A, respectively). Hereby, the first channel 5 communicates with the chamber 7 substantially only via the member's 8 central passage 10. 

  As a consequence of this the a-phase will be prolonged as shown by means of the broken curve line in figure 5A, since it takes longer time to evacuate the pulsation spaces via the central passages 10 than via a tubing 26a, b which lacks an apparatus D, D' according to the invention.



  During the b-phase, when the pulsation space in the teatcup is evacuated, the pressure in the chamber 7 is substantially constant. When the pulsator 27 causes atmospheric pressure alternatively overpressure in the chamber 7, the member 8 is sucked alternatively pushed towards the other seating 15, 14', where the other channel 6, 5' communicates with the chamber 7 via the member's 8 central as well as its peripheral passages  10, 16a-d. Hereby, the pulsation curve keeps its normal character in the c-phase (see figure   5A).   



  In some cases it may be desirable to achieve a normal a-phase and a prolonged c-phase (see the broken curve line in the pulsation curve in figure   5B).    This is achieved by turning the apparatus according to figure 1A-1D or figure 3A in the tubing 26a, 26b, respectively, so that the second throughgoing channel 6, 5' is closest to the pulsator 27 and the first throughgoing channel 5 is closest to the claw piece 25. Hereby, it takes a longer time to fill the pulsation spaces, since the air can only pass through the member's 8 central passage 10 during the c-phase.



  Alternatively, the apparatus D' according to the second embodiment is used with the member 8 turned according to figure 3B. Then the first channel 5 communicates with the chamber 7' via the member's 8 central and peripheral passages 10, 16a-d, while the second channel 5' communicates with the chamber 7' only through the member's 8 central passage 10.



  If both the a- and the c-phase is to be prolonged as shown with broken curve lines in figure 5C, an apparatus
D' according to the second embodiment is used with the modified member 8' according to figure 3C. Hereby the first and the second throughgoing channel 5, 5', respectively, communicates with the chamber 7' only via the member's 8 central passage 10, when the pulsation space is evacuated and filled with air, respectively.



  Alternatively, two opposedly directed apparatuses D according to the first embodiment as shown in figure  1A-1D is used in each tubing 26a, 26b, whereby the same result is achieved (prolonged a-phase and c-phase).



  If an unchanged pulsation curve is desired (which may be suitable during milking of certain, hardy cows), as shown by means of a continuous curve line in the figures 5A-C, the most simple measure is to take away the member 8 from the chamber 7, 7'   burthen    the possibility disappears to indicate the pulsation. For this reason an apparatus according to the first embodiment is used in this case with turned member 8, as shown in figure 2A2B. Alternatively an apparatus D' according to the second embodiment with the modified member 8" shown in figure 3D is used. 

  From this follows that the first and the second throughgoing channel 5, 5', respectively, communicates with the chamber 7, 7' through the members' 8, 8" central as well as peripheral passages 10, 16a-d, respectively, when the pulsation space is evacuated and filled with air, respectively, whereby the apparatus D indicates the pulsation without causing more than an insignificant pressure drop in the tubing 26a, b.



  The present invention is of course not limited to be used in milking equipments. Accordingly, it may also be used for other purposes, such as cleaning of pipes in general with a suitable liquid or a gas, which could be abrasive. In this case, the apparatus according to the invention is utilized to change the abrasive effect of the fluid, such that the flow is rendered slower or faster in different flow directions.

Claims

1. Apparatus (D, D') comprising a housing (1,1') forming a channel (5,6,7; 5,5',7') for a reciprocating fluid, and a member (8) arranged in the channel and adapted to accomplish a first throughflow area in a first position (figs. 1A, 3A, 3C) for said fluid in the channel and to accomplish a second throughflow area in a second position (fig. 1B, 2B) for said fluid in the channel, characterized in that the member (8) is adjustable such that it accomplishes a third throughflow area (figs. 2A, 3B), which is different from the first throughflow area when the member (8) is in the first position.

2. Apparatus according to claim 1, characterized in that said member (8) is movable along the channel (7,7') between the first and the second position.

3. Apparatus (D, D') comprising a housing (1,1') forming a channel (5,6,7; 5,5'7') for a reciprocating fluid and a member (8,8') arranged freely movable in the channel between a first and a second position in the channel, without stopping the fluid flow, characterized in that the member (8,8') is adapted to change the throughflow area in the channel when the member is at least in the first position (figs. 1A, 3A, 3C).

4. Apparatus (D') according to claim 3, characterized in that the member (8') is adapted to change the throughflow area in the channel (5,5',7') when the member is in the first as well as in the second position (fig. 3C).

5. Apparatus according to claim 4, characterized in that in the channel (7') there is provided a first seating (14) and a second seating (14') respectively, against which said member (8') abuts when it takes said first position and second position, respectively, that a first throughflow area in the channel is formed by at least one passage (10) in the member, when the member abuts the first seating and that a second throughflow area in the channel is formed by said passage, when the member abuts the second seating.

6. Apparatus according to claim 3, characterized in that the member (8) is adapted to accomplish a first throughflow area in the channel in the first position and to accomplish a second throughflow area in the channel in the second position.

7. Apparatus according to claim 6, characterized in that the member (8) is adjustable such that it accomplishes a third throughflow area (fig. 2A, 3B), which is different from the first throughflow area when the member (8) is in the first position.

8. Apparatus according to any one of claims 1-2 or 7, characterized in that the housing (1,1') comprises at least two parts (2,3; 2,2',19) which are disengageably connected to each other in such a way that said member (8) is accessible for said adjustment for accomplishment of the third throughflow area when said parts of the housing are released from each other.

9. Apparatus according to any one of claims 1-2 or 6-8, characterized in that the first throughflow area is smaller than the second throughflow area.

10. Apparatus according to any one of claims 1-2 or 7-9, characterized in that the third throughflow area is larger than the first throughflow area.

11. Apparatus according to any one of claims 1-2 or 7-10, characterized in that the third throughflow area is substantially of the same size as the second throughflow area.

12. Apparatus according to any one of claims 1-2 or 6-11, characterized in that in the channel (5-7; 5,5',7') there is provided a first seating (14) against which said member (8) abuts when it takes said first position and a second seating (15; 14'), against which the member (8) abuts when it takes said second position.

13. Apparatus according to claim 12, characterized in that the member is formed with at least one substantially central passage (10) and at least one peripheral passage (16a-d).

14. Apparatus according to claim 13, characterized in that that the first throughflow area is formed by the central passage (10) of the member (8) when the member abuts the first seating (14) and the second throughflow area is formed by the central passage (10) and peripheral passages (16a-d) of the member, when the member (8) abuts the second seating (15; 14'), and that when the member is in its first position and is adjusted to accomplish said third throughflow area this is formed by the member's central (10) and peripheral passages (16a-d).

15. Apparatus according to claim 14, characterized in that the member (8) is guided in such a way by the housing (1,1') that a first side of the member is closest to the first seating (14), while a second, opposite side of the member (8) is closest to the second seating (15; 14'), and that for accomplishment of the third throughflow area, the member (8) is turnable when said parts (2, 3; 2, 2', 19) of the housing (1) are disconnected from each other, whereby said first side of the member is closest to the second seating (15; 14') while said second side of the member (8) is closest to the first seating (14) when the member (8) is turned.

16. Apparatus according to anyone of the preceding claims, characterized by means (3b,19) adapted to indicate the movement of the member.

17. Apparatus according to claim 16, characterized in that said means (3b,19) comprises a transparent portion of the housing (1,1'), whereby the movement of the member (8,8',8") is visually indicatable.

18. Apparatus (D') consisting of a set of parts and comprising a disconnectible housing (1'), which forms a channel (5,7',5') for a fluid; three interchangeable members (8,8',8"), which are each movable in the channel between a first and a second position (14,14'); and means adapted to indicate the movement of each member (8,8',8");

wherein a first member (8) of said three members is adapted to accomplish a first throughflow area in said first position (14), and to accomplish a second throughflow area in said second position (14'), wherein the first throughflow area is different from the second throughflow area (fig. 3A); a second member (8') of said three members is adapted to accomplish a reduced first throughflow area in the channel in said first position (14) and to accomplish a reduced second throughflow area in the channel in said second positon (14'), wherein the first throughflow area is substantially as large as the second throughflow area (fig. 3C);

and wherein a third member (8") of said three members is adapted to accomplish a substantially unreduced first throughflow area in the channel in said first position (14) and to accomplish a substantially unreduced second throughflow area in the channel in said second position (14') wherein the first throughflow area is substantially as large as the second throughflow area (fig. 3D).

19. Milking equipment (20) comprising a pulsator (27) intended to be connected to a pneumatic source (28), and at least one teatcup (21a-d) consisting of a shell (22a-d) and a liner (23a-d), wherein a pulsation space is formed between the shell and the liner, characterized in that the pulsator (27) is adapted to communicate with said pulsation space via an apparatus (D, D') according to any one of the preceding claims.