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EP 0 118 403 B1 |
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EUROPEAN PATENT SPECIFICATION |
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Mention of the grant of the patent: |
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16.07.1986 Bulletin 1986/29 |
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Date of filing: 02.02.1984 |
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Back flow preventing device in the outlet pipe of a pump
Einrichtung im Auslass einer Pumpe zur Vermeidung von Rückströmung
Dispositif dans le tuyau d'émission d'une pompe pour éviter des courants contraires
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Designated Contracting States: |
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DE FR GB IT NL |
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Priority: |
15.02.1983 SE 8300797
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Date of publication of application: |
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12.09.1984 Bulletin 1984/37 |
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Applicant: Flygt AB |
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S-171 25 Solna (SE) |
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Inventor: |
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- Svensson, Roland
S-162 43 Vällingby (SE)
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Representative: Larsson, Sten |
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Flygt AB
Box 1309 171 25 Solna 171 25 Solna (SE) |
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Note: Within nine months from the publication of the mention of the grant of the European
patent, any person may give notice to the European Patent Office of opposition to
the European patent
granted. Notice of opposition shall be filed in a written reasoned statement. It shall
not be deemed to
have been filed until the opposition fee has been paid. (Art. 99(1) European Patent
Convention).
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[0001] This invention concerns a float supported device which controls the pump outlet with
reference to the receiver.
[0002] When pumping a liquid into a receiver having a changing liquid level, the outlet
pipe from the pumps must end on a level which is somewhat higher than the maximum
level of the receiver to ascertain that the liquid does not flow backwards through
the pump when the latter is not working. A disadvantage is that the static head then
is higher, sometimes much higher, than the difference between the levels of the pump
inlet and the receiver respectively, thus causing considerable energy losses.
[0003] Another method is to provide the outlet pipe with a check valve which prevents the
liquid from flowing back. Such a valve is however very sensitive to strokes and also
demands an essentially horizontal outlet pipe having additional tube losses.
[0004] A third possibility is to arrange the outlet pipe bent in such a way, that its upper
part always is above the liquid level in the receiver, a so-called siphon. Such a
device has however considerable losses and in addition there may be problems at pump
start if the liquid level in the receiver goes below the outlet of the siphon.
[0005] The problem to arrange the outlet from a pump at an optimum level is solved by help
of a device according to the following claims.
[0006] The invention is described more closely below with reference to the enclosed drawing.
[0007] In the drawing 1 stands for a submersible pump unit having an inlet 2 and an outlet
3. 4 stands for the outlet pipe and 5 for an outer telescopic pipe axially movable
on the first pipe. 6 stands for a float and 7 and 8 for different liquid levels.
[0008] The submersible pump unit 1 transports the liquid through the pipes 4 and 5. The
buoyancy of the float 6 is so chosen, that the upper end of the pipe 5 is at a suitable
height above the surface 7 to prevent backflow when no pumping takes place. If the
liquid level changes (7'), the end of the pipe 5 is automatically adjusted, as the
pipe may be moved along the rigid pipe 4.
[0009] During pumping the downhead force from the pumped liquid lowers the float 6 so that
the static head is minimized for each level of the receiver. This means of course
also that the energy losses are minimized which is also accentuated by the fact that
the liquid flows out around the entire periphery of the pipe.
[0010] The advantages of the invention are above all the following:
[0011] The static head, that is the distance between the levels 7 (7') and 8, is always
minimized.
[0012] The width of the outlet is maximized as the liquid flows out around the entire periphery
of the pipe.
[0013] No outer controlling means are needed.
[0014] The control forces are balanced and indepen- dant of the water depth of the receiver.
[0015] All forces from the liquid are taken up radially.
[0016] The closing time is almost zero.
[0017] No pressure strokes occur.
[0018] The energy losses are minimum.
[0019] I the drawings a submersible, so-called propeller pump is shown. The invention is
however possible to use also in connection with other types of pumps within the scope
of the invention.
1. A device for preventing back flow through the outlet pipe of a pump which pipe
ends in a receiver for pumped medium, characterized in, that it comprises a telescopically
movable pipe (5) on the essentially vertical outlet pipe (4), which pipe (5) is connected
to a float (6) which keeps the upper end of the pipe at a suitable height above the
liquid level of the receiver.
2. A device according to claim 1, characterized in, that the float (6) is so dimensioned
that the force from the outgoing liquid influences on the level of the float such,
that the static head, that is the difference between the levels (7) or (7') and (8),
is minimized.
1. Vorrichtung zum Verhindern eines Rückflusses durch das Auslassrohr einer Pumpe,
das in einen Aufnahmebehälter für das Fördermittel mündet, dadurch gekennzeichnet,
dass sie ein auf dem im wesentlichen vertikalen Auslassrohr (4) teleskopisch verschiebbares
Rohr (5) aufweist, das mit einem Schwimmer (6) verbunden ist, welcher das obere Ende
des Rohres in einer geeigneten Höhe über dem Flüssigkeitsspiegel des Aufnahmebehälters
hält.
2. Vorrichtung nach Anspruch 1, dadurch gekennzeichnet, dass der Schwimmer (6) so
bemessen ist, dass die von der austretenden Flüssigkeit ausgeübte Kraft die Höhe des
Schwimmers so beeinflusst, dass die Druckhöhe, d.h. die Differenz zwischen den Flüssigkeitsspiegeln
(7) oder (7') und (8), auf ein Minimum reduziert ist.
1. Dispositif pour éviter le reflux par le tuyau de sortie d'une pompe qui débouche
dans un récipient de l'agent pompé, caractérisé en ce qu'il comporte un tube mobile
télescopique (5) sur ledit tuyau de sortie sensiblement vertical (4), ce tube (5)
étant relié à un flotteur (6) qui maintient l'extrémité supérieure du tube à une hauteur
convenable au-dessus du liquide dans ledit récipient.
2. Dispositif selon la revendication 1, caractérisé en ce que le flotteur (6) est
dimensionné de façon que la force du liquide sortant agisse sur le niveau du flotteur
et que la hauteur manométrique, c'est-à-dire la différence entre les niveaux (7) ou
(7') et (8), soit minimisée.