GB2127980A - Measuring contents of containers - Google Patents

Abstract

A portable weighing device receives the bottom edge or rim of a container to be weighed on a load bar (3) fitted with strain gauges. Using a full container and an empty container, an electronic control unit can be calibrated to read the contents of similar containers in appropriate units. The control unit can store information from different types of container. <IMAGE>

Description

SPECIFICATION Container contents measurer The invention described herein describes and clearly explains a method of measuring the contents of containers such as oil drums, gas bottles, (i.e. calor, oxygen types etc.) also beercasksand beer kegs. It is also claimed to measure the contents of all cylindrical tubed containers in a detached condition (detached means free standing and moveable) of all kinds. This unit in its function can also be used for counting, and filling up containers of all kinds to desired contents.

This application also claims priority from my previous application No. 821 8833 filed atthe patent office on 30th June 1982 describing a similar device using an analogue meter system.

This invention relates to a method of measuring the contents of containers, such as oil drums, beer kegs, oxygen and or calor gas bottles, chemical containers, containers holding liquid or solid contents whether pressurised or not, cylindrical orflattypecontainers.

The contents of containers at some stage have to be accounted for intheirfull orpartiallyfull state. In the measurement of closed or pressurised containers this is normallyjudged by weight or bytilting and guessing their contents, which is not an accurate method at all.

The invention herein described is an electron1'c measuring device, using strain gauges, coupled to an amplifier, onto which a series of calibration circuits allowing various containersto bequicklyand easily measured. It is designed to be battery operated allowing itto be portable. Aspecifisdetail of the invention will now be described by way of example with reference to the accompanying drawings in which: FIGURE 1 shows the circuit diagram FIGURES 2 to 6 show a full scale design of the Unit FIGURE 7 shows the strain gauge mounting bar and wire connections FIGURE 8 shows the method of applying a container to it for measurement.

Referring to the drawing Figure 1 which shows the circuit diagram, all of the components except four SG1 -2, SWi -2-3 and meter can all be mounted on a standard single track printed circuit board.

Circuit diagram for container contents measuring instrument (circuit shows a six (6) position container selector switch with corresponding pre-set potentiometers for gain and tare). As claim suggests range can be increased by increasing switch positions plus gain and tare pre-set potentiometers. Drawing Figure 2to 6 showsthesuggested mechanical assemblyofthe device. The device obviously has to be strong and therefore a diecast box [1] is used along with a steel base plate [2]. The load bar [3] is of gauge plate because of the extreme weight which could be applied to it. A spacer between the load bar and base plate [4] is of steel to give strong enough support to the load bar under stress.The load bar cover [5] is aluminium channel to coverthe strain gauge mounted on the top ofthe load bar. Astrong steel half round bar t61 is screwed orwelded to the load barto supportthe bottom edge ofthe container being measured. The load barcover is screwed [7] to the load bar by 3 mm x 5 mm pan head screws. As a bumper protection of the diecast box [8] is a rubber stop stuck onto the side of the box.

Other external parts are a push button switch [9] which is SW3 on Figure 1-for meter illumination, a rocker switch [10] is SW2 of Figure 1-the on/off switch. Meter [11] is the LCD type referred to in Figure 1 - as meter. The container selector switch [12] is SW1 a and SW1 b on Figure 1.The battery compartment [19] is a drawer type case for a PP3 9 volt dry cell.

There are various port holes in the sides of the case marked [13] and [14]. [13] isthe port hole leading to VR1 of Figure 1 -- [14] arethe port holes leading to the pre-settareand gain calibration controls, PS1 to 12 of Figure 1 - if a printed circuit board is used [14] on this side of box are suitable. The load bar assembly Figure 7-shows the method of mounting the strain gauges SC1 -SC2.The solder pads [A.B.C.] for connecting the wires ofSG1 and SG2 are with reference to circuit diagram Figure 1 -SG1 -SG2-A.B.C. Screw holes [16-1 6a- 17-18] are for connecting to other metal work. [16] is aS mm clearance with [16a] being countersunk on the underside of the load bar. The container support [6] is screwed in this position. [18] are 3.5 mm taped holes for mounting the load bar to the base plate [2], via steel spacer [4]. [17] are the two holes 1 mm for feeding the wires of SG2 through the load barforconnection to solder pads [B] and [C].

This forms the description of the Unit. The electronic component critical in terms oftemperatu re tolerances and operating percentages, a list ofwhich is enclosed.

Calibration Procedure: (example: using beer on tainerofeleven (11) gallon capacity).

One empty container and one full container is used as basic calibration.

If container selector switch is putto position number one (1) unit is switched on, tilt keg and place the bottom rim ofthe keg on the load bartip, press down on the top of the container and release, (this isto ensurethatthefull weight of the container ison the load bartip). By inserting a screw driver ortuning tool into the tare (tare means empty) port position number one (1) and turn right or left until the meter reads 00.0 (zero). Remove empty container and replace as before with full container, insert screw driver or tuning tool into the gain (gain in this case means full container) port of position number one (1 ) turn to the right orto the left until the meter reads 11.0 or eleven gallons, checktare again for slight drift and adjust if required.

Once this is done position number one (1) is calibrated to measure all eleven (11) gallon containers of this type. The same procedure is repeated forthe otherfive (5) positions.

The drawings only show six (6) positions but by increasing the switch positions together with one (1 ) gain port control and one (1) tare control the unit can be extended further.

The full weight of the container is obviously not on [6] in Figure 3-this does not matter simply because when calibrating as described in previous text, by placing an empty' container on [6] Figure 3-and zeroing (00.0) the meter, then placing a full container on [6] Figure 3-and then setting the meterto the full contents of the container, the difference in partially full kegs is accuratelydisplayed. What in fact has been done, is the actual weight of the container has been converted by means of calibration to the full weight, so therefore, partiallyfull containers will display a reading somewhere between zero and full.When the unit has no container on [6] Figure 3-- itwill read minus(-) number, this number is in factthe weight of the container converted into gallons and pints (if liquids are being measured). Therefore the need to know exactly what the containers weigh is, by this method, but now required.

COMPONENTSLISTFORCIRCUITDIAGRAMDRAW- ING NO. 1 (Digital version of 'Container Contents Measurer') COMPONENTS LIST.

Resistors: R1 andR4= 180Kohms(seefootnote) R2 and R5 = 120ohms R6=1Mohms R7 = 56K ohms R3 and R8 = 500R ohms (see foot note) Note: [a] R1 -2-4-5-6-7 are all 1/4watt 1% (percent) metal film resistors.

[b] R3- 8 are precision wire would tolerance 0.1% (percent) powertaring 0.33 watts at 85"C (They are an ultra high stability, used in the 'container contents measurer' fortemperature control).

FOOT NOTE: By eliminating RI and R4and by changing the value of R3 and R8to 5K ohms precision wire wound resistors it is possible to slightly reduce temperature drift further.

Capacitors: C1, C2, C3 are 0.1 ilF Suppression class 'X' metallised polyester film with temperature range: -55"C to + 1 00 C C3 = 100 ijF at 16 volts working (standard).

Miniature Pre-set Potentiometers: Ps 1 to 13 are 10 K ohms miniature horizontal mounting cermet presets with carbon brush wipers, linear track rating 0.75 watt at 400C (0.5 watt at 700C) operating temperature range -40"C to + 1 25 C. Toler ance 20%. Ps 13 can bea panel mounted potentiometer of conductive plastic of 10 K ohms value, as this is the drift control.

Miniature 25 Turn Trimmer: VR1 this is a 25 turn cermettrimmer, value K ohms and has a slipping clutch at both ends.

Temperature range -50 Cto + 125"C. Mechanical tolerance 25 turns +5turns. Electrical tolerance 10%.

Voltage Regulator: Voltage Regulator: this is a fixed 100 mA regulator with internal over-load, thermal and short circuit protection, total dissipation 600 m watts at ambient temperature of 25"C with a positive output voltage of 5 volts. Tolerance +5%.

Switches: SW1 is a standard two pole six way wafer type switch (this range can be increased if required, along with gain and tare pre-set potentiometers).

SW2 is a single pole single throw switch such as a rockertype rated at 28volts DC at 4 amps, contact resistance 5 M ohms.

SW3 is a sub-miniature push button momentary action type switch rating 100 m amps at 30 volts DC (max.) Integrated Circuit: I.C.1 is an ultra low off-set voltage operation amplifier (eight pin device). This particular device provides excellent low noise, high accuracy amplifica tion or ofvery low level signals. (A P.M.l. [Bourns] type O.P.-07-E.P.) Strain Gauges: SG1 -2 are strain gauges these are precision strain gauges which give continuous static measurements over a temperature range of -75"C to +1750C (-1950C to +205"Cforshortterm exposure). It has self temperature compensation matched to the load bar characteristics. Also, they are 350 R ohms + 0.15% giving extremely low current drain as a PP3 9 volt battery is used to powerthe unit.

Meter: This is a liquid crystal display 3 digit meter with a built-in back light incorporating a dual-slope-integrating analogue-to-digital converter. It has a precision voltage reference. It also features a battery voltage monitorwhich causes low batterywaming lBAT.] to be shown when battery voltage drops to 7.25 volts. It has an operating temperature range of 0 C to +50"C.

The meter also uses a 9volt35 mA 1000 hour life bulb for illumination ofthe scale.

Claims (10)

1. Asmall portable weighing device, mounted on a flat steel base supporting a strain measurement device with an adjacent box containing controls and calibration facilities, for measuring all forms of detached containers. Only one edge of the container needs placing on the device to give an accurate measurement of its contents. It has a capability of measuring liquid or solid contents. It can store the information of many containers via a multiple range switch. Itdoes not need connectingto anyform of external powersupply.A digital reading can be given in gallons and tenths of gallons or in pints, or in litres.

It has a temperature off set drift control.

2. A container contents measuring device as claimed in Claim [1] wherethetotal unit is mounted on a small hand base which enables itto be used in areas where it is not practicable to move containers.

3. A container contents measuring device as claimed in Claim [1] or Claim [2] where on the device is temperature compensated with a manual drift control to compensatethe container load bar and the electronics.

4. A container contents measuring device as claimed in Claim [2] and Claim [3] which can be made to measure all forms of detached containers, i.e. beer kegs and casks, oil drums, chemical containers, calor gas or oxygen type bottles, cylindrical orflattypes holding liquid or solid contents.

5. A container contents measuring device as claimed in Claim [1] and in Claim [4], it is able to measure all forms of detached containers because only one edge or rim ofthe container is placed on the unit and not the full container.

6. A container contents measuring device as claimed in Claim [1] and in Claim [5], although only one edge of the container is placed on the unit, it will give a high degree of accuracy and also eliminate the empty weight of the containers.

7. Acontainercontents measuring device as claimed in Claim [1] and Claim [6], the empty weight is eliminated, as during calibration the container when empty will give a meter reading of zero (0.00) but when there is no container on the unit the meter will read a minus (-) number.

8. A container contents measuring device as claimed in Claim [1] and in Claim [7], where as the unit is calibrated on a full and empty keg, many types of containers full and empty weights can be stored into the unit.

9. Acontainercontentsmeasuring device as claimed in Claim [11 and in Claim [7] and in Claim [8], where the storage of information is retractable via a multi range switch. Each position of the range switch holds the information on each container. This information is the various emptyweight of the containers,which shows up on the meter as minus(-) numbers, which means when the range switch is in a position for a particular container.And that container (empty) is put on to the unit the meter will show zero (00.0). Therefore, any contents in acontainerwillshow a plus (+) number and if reading liquids will show in gallons and in tenths of gallons, or pints, or litres, or even in imperial or metric weight, if the unit is measuring solid weight in containers.

10. A container contents measuring device sub stantially described herein, with reference to Figure Nos. [1]to [8] oftheaccompanyingdrawings.