Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
  • G01F11/00—Apparatus requiring external operation adapted at each repeated and identical operation to measure and separate a predetermined volume of fluid or fluent solid material from a supply or container, without regard to weight, and to deliver it
  • G01F11/28—Apparatus requiring external operation adapted at each repeated and identical operation to measure and separate a predetermined volume of fluid or fluent solid material from a supply or container, without regard to weight, and to deliver it with stationary measuring chambers having constant volume during measurement
  • G01F11/282—Apparatus requiring external operation adapted at each repeated and identical operation to measure and separate a predetermined volume of fluid or fluent solid material from a supply or container, without regard to weight, and to deliver it with stationary measuring chambers having constant volume during measurement for fluent solid material not provided for in G01F11/34, G01F11/40, G01F11/46

Definitions

• the present invention relates to a method of metering a pulverulent or particulate material.
• British patent specification No . 1, 492 , 033 discloses a metering apparatus having a tubular measuring chamber with compressible inlet and outlet end portions , of which end portions the inlet end portion is communicating with a feeding hopper .
• the compressible inlet and outlet end portions are surrounded by chambers , and by supply of vacuum and pressurized air, respectively , to these chambers , the said end portions may alternately be opened and closed by compression in such a time sequence that the measuring chamber is alternately filled with the material to be metered through the inlet end portion , and emptied through the outlet end portion .
• the present invention provides a metering method allowing an especially accurate metering and a substantially airless sluicing of the metered amounts of material into a container or treating plant, or another receiver.
• the method according to the invention comprises the use of a measuring chamber having compressible inlet and outlet end portions communicating' with an inlet and outlet space, respectively, each of said end portions being alternately closed by compression and opened in such a timed sequence that material is introduced into the measuring chamber, while the inlet end portion is open and the outlet end portion is closed, that a metered amount of material is thereafter enclosed within the measuring chamber by closing the inlet end portion , and that the metered amount of material is then discharged into the outlet space by opening the outlet end portion of the measuring chamber, and the method according to the invention is characterized in that a pressure substantially lower than the pressure within the inlet space , is generated in the outlet space as well as in one or more spaces or chambers surrounding the compressible wa ⁇ parts of the measuring chamber .
• the particles of the material to be metered will be tightly packed together when the material is sucked or pressed into the measuring chamber, and because the inlet end portion of the measuring chamber is tightly closed when the outlet end portion is opened, the metered amount of material will be sluiced from the inlet space to the outlet space substantially free of air .
• the compressible inlet and outlet end portions of the measuring chamber permits an air-tight closing of the end portions of the measuring chamber in a simple manner without using complicated or vulnerable valve devices .
• the compressible parts of the measuring chamber may be made from a highly flexible material, such as rubber or soft plastic , and in the preferred embodiment the measuring chamber is formed by a flexible tube or hose length of such a material.
• the invention also relates to a metering apparatus for carrying out the method described above, and the apparatus according to the invention is of the type comprising a measuring chamber having compressible inlet and outlet end portions communicating with inlet and outlet spaces , respectively , and means for compressing the inlet and outlet end portions , respectively , and the apparatus according to the invention is characterized in that means are provided adapted to generate within the outlet space a pressure which is substantially lower than the pressure within the inlet space , that the measuring chamber and the inlet and outlet end portions thereof are surrounded by an outer chamber, and that means are provided adapted to generate in this outer chamber a pressure which substantially corresponds to the pressure within the outlet space .
• the measuring chamber is advantageously formed by a flexible tube or hose length, which may be surrounded by a rigid tubular body extending between the end portions thereof, the inner diameter of said body being substantially equal to the outer diameter of the tube or hose length in its non-tensioned condition.
• a sxiitably low pressure for example, in the same order as the pressure within the outlet space is maintained within the outer chamber surrounding the tube or hose length , this length will assume a shape determined by the inner surface of the rigid tubular body, even when the tube or hose length is made from a relatively soft material in order to facilitate compression of the end portions of said tube or hose length.
• Fig. 1 is a side view and partially sectional view of a metering apparatus
• Fig. 2 is a side view and partially sectional view in an enlarged scale of part of the apparatus shown in Fig. 1
• Fig. 3 is a side view and partially sectional view of a tube or hose length forming the measuring chamber in the apparatus shown in
• the metering apparatus shown in the drawings is adapted to introduce metered amounts of pulverulent or particulate material into a production or treating plant, for example for introducing milk powder into a milk recombining plant as that described in applicant's Danish patent application No . 3161/80.
• the apparatus may, however , also be used for metering other kinds of pulverulent or particulate materials in cases where an accurate metering of amounts of material substantially free of air is desired.
• the apparatus may also advantageously be used for metering liquid materials , especially when they are relatively viscous or paste-like
• the apparatus shown in the drawings has an upwardly open material feeding hopper or a material reservoir 10 in which the material 11 to be metered is arranged.
• the lower outlet end of the hopper is tightly connected to the upper end of a flexible tube or hose length 12 having a sealing flange 13 at each end as shown in Fig. 3.
• the major part of the hose length 12 is surrounded by an outer vacuum chamber 14 having a front wall 15 , which , as shown in Fig. 1 , is removably fastened by means of a plurality of screws IS or similar fastening members , and which is made from a transparent material, such as glass .
• the lower end of the hose length 12 is tightly connected to a tube bend 17 , which is in turn communicating with the suction side of a self-priming pump 18 , which is inserted in a tubing system 19 forming part of a treating or production plant to which it is desired to supply metered amounts of material without entrainment of air.
• the center part of the hose length 12 is surrounded by a rigid tubular body 20 having an inner diameter which subs tan tiaiiv corresponds to the outer diameter of the hose length in the non-tensioned condition thereof , and this body is fastened to the walls of the vacuum chamber by means of radially extending mounting members 21.
• Rigid tubular supporting bodies 23 corresponding to the body 20 is mounted in the opposite end walls 22 of the vacuum chamber 14, and the ends of the hose length 12 extend out from the vacuum chamber 14 through these supportingbodies as shown in Fig.2.
• Opposite side walls of the vacuum chamber 14 are provided with two pairs of aligned, internally threaded mounting sockets 25 for mounting pneumatic or hydraulic cylinders 26 , preferably cylinders actuated by pressurized air .
• Each pair of cylinders 26 has oppositely directed piston rods each having a rotataoly mounted pinch roller 27 arranged at their free ends .
• each pinch roller may comprise a shaft and a cylindrical shell of steel, such as stainless steel, and an intermediate layer of plastics material.
• Each pair of pinch rollers 27 may be moved towards and away from each other by means of the cylinders 25 between a first position, which is indicated with dotted lines in Fig.
• the metering apparatus shown on the drawing operates as follows :
• the centrifugal pump 18 When the centrifugal pump 18 is operating it creates a substantial subatmospheric pressure at the suction side thereof , and when the outlet end portion 29 of the hose length 12 is not pinched this subatmospheric pressure will be transmitted to the measuring chamber 30 through the tube bend 17.
• the function of the cylinder 25 is controlled by means of a conventional control system, not shown, in such a manner that the pinch rollers 27 at any time close either the inlet end portion 23 or the outlet end portion 29 of the hose length 12 , and some times both of these end portions .
• the lower pair of pinch rollers 27 is now caused to close the outlet end portion 29 of the hose length , and immediately thereafter the upper pair of pinch rollers 27 is moved to their retracted position indicated by dotted lines so that the inlet end portion 28 is opened.
• the measuring chamber 30 will immediately be filled with material from the hopper 10 in a tightly packed condition substantially free of air.
• the inlet end portion 28 is closed by means of the upper pair of pinch rollers 27, and immediately thereafter the outlet end portion 29 of .the. hose length 12 is opened thereby that the lower pair of pinch rollers are moved back to their retracted position indicated by dotted lines in Fig. 2.
• the metered amount of material will then immediately be sucked out of the measuring chamber 30 and passed through the tube bend 17 into the tubing system 19.
• the sucking of the metered amount of material out from the measuring chamber 30 causes such a sudden transverse movement of the flexible walls of the chamber that possible sticky , for example moist, residues of the pulverulent or particulate material are released from the walls of the measuring' chamber, whereby the metering apparatus will be self-cleaning .
• the operating cycle of the pinch rollers 27 just described may now be repeated a desired number of times and at a desired rate or portions of material may be introduced into the tubing system 19 without entraining substantial amounts of air . This may i. a . be of importance if the tubing system 19 forms part of a plant , in which the existence of air might, for example , give rise to foaming or oxidation problems .
• the capacity of the centrifugal pump 13 preferably substantially exceeds the capacity of the plant (for example 3 - 6 times)
• the pump may , for example , be of the type marketed by Pasilac A/S , Silkeborg, Denmark, under the designation "ZMS 3" .
• the pressure at the suction side of the pump , and consequently in the measuring chamber 30 may be about 0.4 atmosphere.
• the subatmospheric pressure or vacuum in the measuring chamber may be provided in any other suitable manner for other applications of the apparatus according to the invention , for example by means of a conventional vacuum pump .
• the hose length 12 may suitably be made from a plastic or rubber material having a suitable flexibility and such a strength and wearability that the hose length may resist the repeated mechanical stresses to which it is exposed by the pinch rollers 27.
• the hose length may, for example, be made from natural rubber of a quality marketed by Sch ⁇ nning & Arve , Horsens , Denmark, under the quality designation "6344" .
• the metering apparatus according to the invention may advantageously be used in connection with a plant for recombining milk or other liquid food, products . It should be understood, however, that the metering apparatus according to 'the invention could also advantageously be used for other applications where an accurate metering of material substantially without entrainment of air is desired.
• the total measuring chamber is defined by the flexible hose length 12.
• the measuring chamber itself may, alternatively, have rigid walls provided that the inlet and outlet end portions 23 and 29 are of a material which may be closed by pinching.
• the pinching means need not necessarily be in the form of rollers but could have any other form allowing a tight closing of the end portion of the measuring chamber .
• the pneumatic or hydraulic cylinders for actuating the pinching means could be replaced by other forms of actuating means , such as cams , eccentrics , or the like.
• the vacuum provided within the outer vacuum chamber 14 need not be the same as that provided at the outlet end portion 29 by the centrifugal pump 18.
• the pressure within the chamber 14 may be substantially lower than the subatmospheric pressure provided in the measuring chamber 30.
• the pressure provided within the outer chamber 14 should preferably not be substantially higher than the subatmospheric pressure provided at the suction side of the vacuum pump 18.

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• Physics & Mathematics (AREA)
• Fluid Mechanics (AREA)
• General Physics & Mathematics (AREA)
• Weight Measurement For Supplying Or Discharging Of Specified Amounts Of Material (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=8119796

Family Applications (1)

Country Status (3)

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Family Cites Families (3)

• 1980
  • 1980-07-22 DK DK316280A patent/DK145208C/da not_active IP Right Cessation
• 1981
  • 1981-07-21 WO PCT/DK1981/000073 patent/WO1982000349A1/en not_active Ceased
  • 1981-07-21 EP EP19810902321 patent/EP0056412A1/de not_active Withdrawn

Non-Patent Citations (1)

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