GB2445473A - Metering device which accounts for dripping - Google Patents
Metering device which accounts for dripping Download PDFInfo
- Publication number
- GB2445473A GB2445473A GB0800152A GB0800152A GB2445473A GB 2445473 A GB2445473 A GB 2445473A GB 0800152 A GB0800152 A GB 0800152A GB 0800152 A GB0800152 A GB 0800152A GB 2445473 A GB2445473 A GB 2445473A
- Authority
- GB
- United Kingdom
- Prior art keywords
- liquid
- metered
- metering
- mass
- preset
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 239000007788 liquid Substances 0.000 claims abstract description 95
- 238000000034 method Methods 0.000 claims abstract description 33
- 239000000126 substance Substances 0.000 description 8
- 238000009434 installation Methods 0.000 description 5
- 238000005259 measurement Methods 0.000 description 5
- 238000011160 research Methods 0.000 description 3
- 238000000576 coating method Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 239000000853 adhesive Substances 0.000 description 1
- 230000001070 adhesive effect Effects 0.000 description 1
- 239000006071 cream Substances 0.000 description 1
- 230000003111 delayed effect Effects 0.000 description 1
- 238000009472 formulation Methods 0.000 description 1
- 239000012669 liquid formulation Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 238000005303 weighing Methods 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01G—WEIGHING
- G01G17/00—Apparatus for or methods of weighing material of special form or property
- G01G17/04—Apparatus for or methods of weighing material of special form or property for weighing fluids, e.g. gases, pastes
- G01G17/06—Apparatus for or methods of weighing material of special form or property for weighing fluids, e.g. gases, pastes having means for controlling the supply or discharge
-
- 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
- G01F11/02—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 measuring chambers which expand or contract during measurement
- G01F11/021—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 measuring chambers which expand or contract during measurement of the piston type
- G01F11/029—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 measuring chambers which expand or contract during measurement of the piston type provided with electric controlling means
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01G—WEIGHING
- G01G13/00—Weighing apparatus with automatic feed or discharge for weighing-out batches of material
- G01G13/02—Means for automatically loading weigh pans or other receptacles, e.g. disposable containers, under control of the weighing mechanism
- G01G13/04—Means for automatically loading weigh pans or other receptacles, e.g. disposable containers, under control of the weighing mechanism involving dribble-feed means controlled by the weighing mechanism to top up the receptacle to the target weight
-
- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
- G05D7/00—Control of flow
- G05D7/06—Control of flow characterised by the use of electric means
- G05D7/0617—Control of flow characterised by the use of electric means specially adapted for fluid materials
- G05D7/0623—Control of flow characterised by the use of electric means specially adapted for fluid materials characterised by the set value given to the control element
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Fluid Mechanics (AREA)
- Engineering & Computer Science (AREA)
- Automation & Control Theory (AREA)
- Feeding, Discharge, Calcimining, Fusing, And Gas-Generation Devices (AREA)
Abstract
The invention relates to a method for metering liquids using a metering apparatus whereby a desired mass of the liquid is to be metered. In a first step S1, a liquid is metered into a container, the metering of the liquid being performed volumetrically. In S2 the mass of the added liquid is determined. After a preset waiting time, in step S3, the mass of the added liquid is re-determined in S4. Step S5 comprises obtaining the difference of the two masses and repeating S3 if the difference exceeds a preset value. If necessary, the steps S3 - S5 are repeated until the difference between the measured masses falls below a preset value. Step S6 comprises comparing the mass of metered in liquid with the desired mass of liquid, and if they are the same (or within a preset deviation) the process is terminated. Otherwise steps S1 - S6 are repeated. The invention furthermore relates to an apparatus for carrying out the method.
Description
2445473
14 December 2006 Description 5 Title
Method and apparatus for metering liquids
Prior art
10 The invention relates to a method for metering liquids according to Claim 1 and to an apparatus for metering liquids according to Claim 8.
In the production of liquid formulations, for example 15 coatings, adhesives, creams, foodstuffs, etc., liquids having very different flow properties have to be metered with the greatest possible accuracy. The liquids may, for example, be of low or high viscosity, exhibit Newtonian or non-Newtonian behaviour or have a flow limit.
20
At present, in particular in fully automatic installations, as employed for example for high-throughput research, different liquids are metered in using different metering systems or it is necessary to set a large number of 25 parameters for each liquid. Thus, for example, the use of line dispensers is restricted to low-viscosity liquids or it is necessary to operate with initial pressure.
Customarily, the metering apparatuses known from the prior 30 art work volumetrically. Such metering apparatuses are, for example, pump metering modules. Since, however, it is customary, in the formulation of coatings for example, to specify the metering masses, for such metering apparatuses
2
the density must be known very precisely in order for precise gravimetric metering to be possible.
The gravimetric metering is performed in a plurality of 5 steps, as known for example from DE-A 101 59 272. In this case, the control of the metering of the sub-steps following the first step is performed in each case on the basis of the mass flow rate calculated in the previous sub-step.
10
The disadvantage of the method known from the prior art is, however, that liquid which continues to run or drip is not taken into account in the metering. Highly precise metering is thus not possible. Continued running results, for 15 example, from the high pressure required if the viscosity of the liquid is high or if compressible liquids, or gas present in the medium, are compressed.
Disclosure of the invention
20
Advantages of the invention
The method according to the invention for metering liquids using a metering apparatus whereby a desired mass of the 25 liquid is to be metered comprises the following steps:
a) metering a liquid into a container, the metering of the liquid being performed volumetrically,
30 b) determining the mass of the added liquid,
c) re-determining the mass of the added liquid after a preset waiting time,
3
d) obtaining the difference of two masses determined at the interval of the preset waiting time and repeating step c) if the difference exceeds a preset value,
5
e) if necessary, repeating steps a) to d) until the difference between the mass of metered-in liquid and the preset mass of the liquid to be metered falls below a preset value.
10
The advantage of the method is that it is not necessary, for the volumetric metering, to determine the precise density after a metering step. In addition, precise metering is possible since continued dripping of the 15 metered liquid is also taken into account. As long as the mass in the container changes between two measurements, liquid is continuing to drip. Thus, dynamic metering is possible, in which the waiting times until continued metering or until the metering of a new liquid are adapted 20 to the liquid to be metered. In the case of liquids where dripping continues for a relatively long time, which is the case for example with liquids having a high viscosity, the waiting time until continued metering is carried out is longer than, for example, with liquids having only a short 25 or no continued dripping time.
A further advantage of the method according to the invention is that no preliminary tests are required to determine the metering parameters, for example the waiting 30 time after metering, in particular in the case of new substances and mixtures. It is also possible to meter very different substances using one metering unit with constantly high precision.
4
The method according to the invention can be employed in fully automatic metering installations, for example in metering installations for high-throughput research, where 5 substances whose properties are not known in advance have to be metered.
Also, errors due to insufficient stiffness of the metering installation are compensated for by the method according to 10 the invention. In addition, each substance is metered as quickly as possible.
Preferably, at least two different liquids are metered in successively using the same metering apparatus. As a 15 result, costs for a further metering unit, for example, can be saved.
In order to take into account the entire liquid which continues to drip, the preset waiting time in step c) 20 between two mass determinations is preferably greater than the falling time of a drop. As a result, the metering-in or continued metering of a substance is terminated only when no further drop falls.
25 In order to exclude any inaccuracies in the mass determination and nevertheless be able to continue metering at the earliest possible point in time, the value preset in step d) for the difference between two masses determined at the interval of the preset waiting time is preferably less 30 than the mass of a drop of the liquid to be metered.
In order to avoid excess metering, it is preferred that the volumetric metering in step a) is performed on the basis of
5
the density of the liquid to be metered. The amount of the liquid to be metered in is initially less than the preset amount. The density is, for example, estimated and a rather somewhat higher value is input in the control. The 5 approximate volume is calculated from the density and the desired value for the mass to be metered in.
If the density of the liquid to be metered in is unknown, it is possible for part of the volume to be metered in 10 first of all. After the metering, the density is calculated from the mass determined in step c) and the metered-in volume. With the aid of the density thus calculated, steps a) to d) are then repeated until the desired mass has been metered in.
15
According to the invention, the method is carried out in an apparatus which comprises a volumetric metering device, a device for determining the mass and means for control, the difference of the mass between a first determination and a 20 second determination being obtained and being able to be compared with a stored value using the means for control.
Examples of suitable volumetric metering devices are syringes or pumps.
25
The waiting time between the first and the second determination of the mass is preferably preset by the means for control. Furthermore, it is also preferred that, using the means for control, a volume to be metered in is 30 determined from a preset density of the liquid to be metered and the desired mass of liquid to be metered. Furthermore, it is also preferred that, using the means for
6
control, the density of the determined mass and the actually metered-in volume is calculated.
Brief description of the drawings
5
An exemplary embodiment of the invention is illustrated in the drawing and is explained in more detail in the following description.
10 The single figure shows a block diagram of the method according to the invention.
Embodiments of the invention
15 A block diagram of the method according to the invention is illustrated in Figure 1.
In a first step SI, liquid is firstly metered volumetrically into a container. If the density of the
20 liquid is not known, it is not possible, by means of volumetric metering, carried out for example with the aid of syringes or pumps, to meter gravimetrically. Monitoring with a balance is required for this. For the metering, the density is estimated and input into a means for control.
25 The input value is preferably greater than the estimated density. As a result, it is possible to avoid metering in too great a mass. From the input density and the desired value for the mass to be metered in, the approximate volume which has to be supplied is calculated.
30
Where the density is not known, the liquid is preferably metered in a plurality of stages. In this case, in step SI, firstly only part of the amount to be metered in is metered
7
in. Thus, for example, firstly 80% of the volume is metered. Of course, any other proportion which is less than 100% of the volume is also possible. This proportion is preferably in the range from 60 to 95%. Subsequently, in a 5 step S2, the mass of the liquid supplied in step SI is determined.
In general, a pressure builds up during the metering step SI. This pressure is greater, the higher the viscosity of 10 the liquid to be metered. Compressible liquids, or gas present in the medium, are compressed. As soon as the volumetric metering is terminated, for example by stopping the advance of the plunger of a syringe, liquid continues to drip or run until the pressure equalisation is 15 completed. This may take different lengths of time depending on the flow properties of the liquid. To avoid excess metering, it is necessary to allow for the time in which liquid continues to run or drip before a next metering step is carried out. If a long waiting time is 20 chosen here, however, even substances which are easy to meter, i.e. substances which continue to run or drip for only a very short time if any, are metered very slowly.
To avoid this, immediately after the volumetric metering in 25 step SI, the mass of the metered-in liquid is determined in step S2. After the mass determination in step S2, a predetermined waiting time is allowed in step S3. The waiting time is preferably greater than the falling time of a drop. The waiting time is preferably likewise input into 30 the means for controlling the metering method. As a result, automatic metering is made possible.
8
After the waiting time in step S3, the mass of the metered-in liquid is re-determined in step S4. If liquid has still continued to run or drip, the mass determined in step S4 differs from the mass of the liquid determined in 5 step S2. A comparison of these two values is carried out in step S5. The comparison can likewise be carried out in the means for controlling the metering method.
For comparing the masses determined in steps S2 and S4, the 10 difference of these masses is obtained and compared with a preset value. This preset value is preferably less than the mass of a drop. It is thereby already detected if the mass between the measurements in step S2 and S4 has increased by the mass of a drop. In this way, continued dripping can be 15 detected. However, in order to exclude weighing inaccuracies, the value with which the difference of the two mass determinations is compared is preferably greater than 0.
20 If the difference of the mass determinations in step S2 and S4 is greater than the predetermined value, the waiting time in step S3 is again allowed. Following that, a re-determination of the mass is performed in step S4.
25 In order to ascertain whether liquid has still further continued to run or drip, the mass now determined in step S4 is compared with the mass determined in the preceding pass in step S4. This is repeated until the difference between two consecutively measured values for the metered-30 in liquid mass is less than the preset value.
After the mass of the liquid between two consecutively performed measurements has no longer changed, this last-
determined value for the liquid mass is compared with the desired value for the mass of the liquid to be added. This comparison is performed in step S6. If it is found in the comparison in step S6 that the mass of the added liquid 5 differs from the desired value of the mass to be added by more than a preset value, it is necessary to continue metering liquid. For this, steps SI to S6 are carried out again as described above. As soon as, in step S6, the difference between the actually metered-in liquid mass and 10 the desired value for the mass of the liquid to be metered in is less than the preset deviation, the metering process is terminated.
The preset deviation between the actually metered-in mass 15 of liquid and the desired value of the mass of liquid to be added is the tolerance within which the metering takes place. This value is preferably likewise preset in the means for controlling the metering process.
20 In order to attain as precisely as possible with the second metering step the preset desired value for the mass to be metered in, it is possible for the density to be calculated from the metered-in volume and the measured mass of the liquid. With this density value, the precise volume of the 25 mass still, lacking can be determined. However, in order to prevent excess metering, somewhat less liquid can be added so that no excess amount of liquid is metered owing to the delayed liquid discharge due to the continued running or dripping. If metering is performed without a waiting time, 30 the pressure at the end of the metering step is not yet reduced and more than calculated continues to run in the next metering step. This can lead to excess metering.
10
Through the repeated measurement in each case after allowing a waiting time in order to ascertain whether liquid has continued to run or drip, the waiting time can be set shorter than the longest waiting time which is 5 required for the substance which continues to drip or run the longest. In this way, dynamic metering is possible. After metering each liquid, it is only necessary to wait until this liquid no longer continues to run or drip. In the case of liquids whose continued dripping or running is 10 quickly ended, the waiting time is short, whereas in the case of liquids which continue to run or drip for a long time, a correspondingly longer waiting time with in each case intermediate measurements is allowed until the next metering step is carried out.
15
The method according to the invention is suitable in particular for the automatic metering of liquids. Thus, the method according to the invention can be used, for example, in a fully automatic installation, for example for high-20 throughput research. In this case, a wide variety of liquids can be metered with constantly high precision.
The method according to the invention can be carried out with any metering apparatus known to a person skilled in 25 the art if this apparatus comprises means for control. Suitable means for control are, for example, control devices or computers. To carry out the method in an automated manner, it is merely necessary to be able to transmit data from the volumetric metering apparatus and 30 from the balance to the control device.
11
Of course, it is also possible, alternatively, to carry out the method according to the invention in a non-automated manner.
Claims (1)
12 Claims
Method for metering liquids using a metering apparatus whereby a desired mass of the liquid is to be metered, the method comprising the following steps:
a) metering a liquid into a container, the metering of the liquid being performed volumetrically,
b) determining the mass of the added liquid,
c) re-determining the mass of the added liquid after a preset waiting time,
d) obtaining the difference of two masses determined at the interval of the preset waiting time and repeating step c) if the difference exceeds a preset value,
e) if necessary, repeating steps a) to d) until the difference between the mass of metered-in liquid and a preset mass of the liquid to be metered falls below a preset value.
Method according to Claim 1, characterised in that at least two different liquids are metered in successively using the same metering apparatus.
Method according to Claim 1 or 2, characterised in that the preset waiting time in step c) is greater than the falling time of a drop.
13
Method according to one of Claims 1 to 3,
characterised in that the volumetric metering in step a) is performed on the basis of the density of the liquid to be metered, the amount of the liquid to be metered in being initially less than the preset amount, in order to avoid excess metering.
Method according to Claim 4, characterised in that the density of the liquid to be metered is estimated if it is not known precisely.
Method according to one of Claims 1 to 5,
characterised in that, in step d), the preset value for the difference between two masses determined at the interval of the preset waiting time is less than the mass of a drop of the liquid to be metered.
Method according to one of Claims 1 to 6,
characterised in that the density of the liquid to be metered in is calculated from the mass determined in step c) and the metered-in volume, before step e) is carried out.
Apparatus for carrying out the method according to one of steps 1 to 5, comprising a volumetric metering device, a device for determining the mass and means for control, the difference of the values of a first and second determination of the mass carried out at the interval of a preset waiting time being able to be obtained and compared with a stored value using the means for control.
14
9. Apparatus according to Claim 8, characterised in that the waiting time between the first and second determination of the mass is preset by the means for control.
5
10. Apparatus according to Claim 8 or 9, characterised in that, using the means for control, a volume to be metered in is determined from a preset density of the liquid to be metered and the desired mass of liquid to
10 be metered.
11. A method of metering liquids substantially as herein described.
15
12. An apparatus for metering liquids substantially as herein described.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE102007001140A DE102007001140A1 (en) | 2007-01-05 | 2007-01-05 | Liquid metering method for producing e.g. adhesive, involves repeating re-determining mass of added liquid after preset waiting time and obtaining difference of two masses to point, where difference falls below preset value |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB0800152D0 GB0800152D0 (en) | 2008-02-13 |
| GB2445473A true GB2445473A (en) | 2008-07-09 |
| GB2445473B GB2445473B (en) | 2009-06-03 |
Family
ID=39477670
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB0800152A Expired - Fee Related GB2445473B (en) | 2007-01-05 | 2008-01-04 | Method and apparatus for metering liquids |
Country Status (2)
| Country | Link |
|---|---|
| DE (1) | DE102007001140A1 (en) |
| GB (1) | GB2445473B (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE102009038146A1 (en) | 2009-08-21 | 2011-03-03 | Heubach Gmbh | Dye set, useful to produce ready-made paint, preferably e.g. floor paint, comprises a substrate component, a shade component and a brightening component with achromatic coloring substances and chromatic coloring substances |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5375634A (en) * | 1993-10-07 | 1994-12-27 | Graco Inc. | Variable mass flow rate fluid dispensing control |
| DE10159272A1 (en) * | 2001-12-03 | 2003-06-12 | Bayer Ag | Method and device for dosing liquids |
-
2007
- 2007-01-05 DE DE102007001140A patent/DE102007001140A1/en not_active Withdrawn
-
2008
- 2008-01-04 GB GB0800152A patent/GB2445473B/en not_active Expired - Fee Related
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5375634A (en) * | 1993-10-07 | 1994-12-27 | Graco Inc. | Variable mass flow rate fluid dispensing control |
| DE10159272A1 (en) * | 2001-12-03 | 2003-06-12 | Bayer Ag | Method and device for dosing liquids |
Also Published As
| Publication number | Publication date |
|---|---|
| GB2445473B (en) | 2009-06-03 |
| GB0800152D0 (en) | 2008-02-13 |
| DE102007001140A1 (en) | 2008-07-10 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN113692321B (en) | Application device and corresponding application method | |
| DE102011122268B3 (en) | Method and device for dosing a fluid medium | |
| KR101927202B1 (en) | Method and apparatus for calibrating dispensed deposits | |
| WO2020220752A1 (en) | Liquid medicine filling control system, filling system, and control method | |
| US11346697B2 (en) | System and method for remote metering station sensor calibration and verification | |
| US8220501B2 (en) | Method for safe filling in valve-controlled filling systems | |
| US20090293986A1 (en) | Method and device to fill receiving containers | |
| US20170333927A1 (en) | Plural component dispensing system | |
| CN1258349A (en) | Overfill compensation for batch delivery system | |
| JP2006120149A (en) | Dosing system and method for fluid media | |
| US20050035146A1 (en) | Apparatus for dispensing liquids | |
| GB2445473A (en) | Metering device which accounts for dripping | |
| CN102806027A (en) | Multichannel liquid mixing system and online liquid mixing system | |
| US10060886B2 (en) | Method for high pressure gradient chromatography using pump stroke control | |
| RU2682063C1 (en) | Method for control of metrological characteristics of fixed or mobile metering installations and calibration unit for its implementation | |
| WO2017160904A1 (en) | Dispenser pump calibration system | |
| CN202087289U (en) | Multi-path liquid mixing system and liquid on-line mixing system | |
| US20190086251A1 (en) | Method of determining a filling level | |
| TW201930875A (en) | Methods for chromatography resin slurry determination | |
| JP2008253876A (en) | Device and method for discharging material | |
| JP2018513010A (en) | Method, device and apparatus for coating an inner surface of a substrate | |
| CN113669250B (en) | Glue pump testing system and method | |
| US11709085B2 (en) | Method for determining a dwell volume of a chromatographic system | |
| CN102805952A (en) | Multichannel liquid mixing system and online liquid mixing system | |
| US20070251597A1 (en) | Method for after-run amount regulation in filling units |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 20180104 |