HYDROMETERS

Abstract: A hydrometer of the kind comprising a transparent tubular chamber (10) in which a float (20) is located and to which a sample of liquid to be tested is brought in order that a characteristic of the liquid may be ascertained by noting the level of the float within the liquid, which is provided with a calculator in the form of an area of coded information (A, B, C, D) viewable on a wall of the chamber (10) and a cursor (30) movable axially and circumferentially of the chamber across the viewed area of coded information to enable conversion of data read from the float within the chamber to another form. Such a hydrometer is particularly useful in testing the concentration of anti-freeze solution in the cooling system of an internal combustion engine.

Description: - l- TITLE: Hydrometers TECHNICAL FIELD The invention concerns hydrometers of the kind comprising a transparent elongate chamber in which a float is located and to which a sample of liquid to be tested is brought in order that a characteristic of the liquid may be ascertained by noting the level of the float within the liquid. BACKGROUND ART Normally such hydrometers comprise a glass or plastics material body in the form of a cylindrical tube having means (e.g. a nozzle) at one end via which liquid may be drawn into the ' hydrometer' by operation " of other means (e.g. a_ resiliently deformable bulb) coupled to the other end of the tube. The level of the float within the sample is determined by the specific gravity of the liquid and is indicated by a graduated scale on the float which a user may view and read through the wall of the tube. An object of the invention is the provision of a hydrometer of this kind which has means enabling information ascertained by inspection of the level of the float to be readily converted to another or more useful form. For example if the characteristic of the liquid being monitored is the concentration of an additive in the liquid the means may provide an indication of the additional amount of the additive to be added to the liquid to bring its concentration in the liquid to a desired level. • DISCLOSURE OF INVENTION An aspect of the invention provides a hydrometer of the kind referred to which is provided with a calculator in the form of an area of coded information on the wall of the chamber and a cursor movable axially and circumferentially of the chamber wall across the area of coded information to enable conversion of data read from the float within the chamber to another form. The area of coded information is preferably formed as an array of indicia relevant to the characteristic being monitored. With advantage the indicia are printed onto a plastics material sleeve fixed to the wall of the chamber. The indicia may indicate; firstly, the concentration of given additive in the liquid being tested; secondly selected volumes of that liquid and thirdly volumes of said additive to be added to that liquid to bring its concentration therein to a desired level. The indicia may be arranged in a plurality of sub-arrays each of which relates to a different desired final additive concentration in the liquid. The indicia or each sub-array thereof preferably comprises a first set of indicia equivalent to indicia provided on the float within the chamber, a second set of indicia indicating different selected volumes of the liquid under test and a third set of indicia enabling determination of the volume of the additive to be added to the liquid to bring its concentration therein to a desired level. With advantage the cursor is in the form of a first ring member movable axially and circumferentially of the chamber to bring a part thereof into juxtaposed relationship with one of the indicia of the first said set, a second ring member rotatably movable on the first ring member to bring part thereof into a predetermined relationship with one of the indicia of said second set so as to bring an indicator of said second ring member into a position identifying one of said third set of indicia which denotes the volume of additive which must be added to the liquid to achieve a desired additive concentration therein. Said parts of the first and second ring members may comprise lugs carried on the edges of the ring members and shaped generally as pointers and said indicator of the second ring member with advantage comprises an aperture formed in the lug of that member. A further aspect of the invention comprises a method of determining the volume of a material which must be added to a liquid under test to bring the concentration of that material in the liquid to a desired level making use of a hydrometer having a calculator as defined. Other aspects, features and advantages of the invention will become apparent from the following description of a hydrometer enabling determination of the additional volume of anti-freeze which must be added to a vehicle coolant system to achieve a desired concentration of anti-freeze therein. BRIEF DESCRIPTION OF DRAWINGS In this description reference is made to the accom¬ panying drawings in which:- Figure 1 is a side view of the hydrometer; Figure 2 is an enlarged view of that part of Figure 1 marked I; Figure 3 illustrates in more detail the indicia on a sleeve shown in Figure 1 , and Figure 4 illustrates an alternative form of the part shown in Figures 1 and 2. BEST MODES FOR CARRYING OUT THE INVENTION .The hydrometer-in ' the drawings comprises-a clear glass body 10 in the form of an open ended generally cylindrical tube one end, 12, of which carries a nozzle 14 and the other end 16 of which is coupled to a resiliently deformable bulb 18. Within body 10 is located a glass bulb float 20 of conventional form an having a graduated scale 22 on an upper portion 25 of it as shown. A float retaining buffer 26 is provided to prevent portion 24 of float 20 entering the resilient bulb 18. The lower part of body 10 has fitted therearound a sleeve 28 of plastics material. Sleeve 28 is shown 'unwrapped' in Figure 3, from which it can be seen that the sleeve has an array of indicia printed thereon, the indicia being disposed in four sub-arrays. The hydrometer further comprises a cursor 30 movable axially and circumferentially of the body 10 across the indicia printed on the sleeve 28. Cursor 30 has two parts, one being a first ring member 32 formed with a lug 34 of the double headed arrow shape shown and the other being a second ring member 36 located on the first member and rotatable around the first member. Movement of the first and second members relative to one another axially of the body 10 is prevented by a shoulder 38 against which the second member 36 abuts. The second member 36 is formed with an arrow shaped lug 40 in which an aperture 42 is provided and through which indicia on the sleeve 28 may be viewed. Desirably the first and second ring members are of different and contrasting colours. In the embodiment shown the indicia on the sleeve are divided into four sub-arrays which are used respectively for determining the volume of anti-freeze to be added to the liquid coolant system of a vehicle to bring the concentration of anti-freeze therein to ones of four different concentrations. The sub-arrays indicated at A, B, C and D are adapted to be used to achieve anti-freeze concentrations of, respectively, 30%, 35%, 40% and 50%. Other final concentration levels may, of course, be selected. Figure 3 shows the sleeve 28 in more detail and shows the four sub-arrays each to comprise three sets of indicia. A first linear set 44 of each sub-array being located along one -6- side of thereof, a second linear set 46 being disposed at the top of the upper sub-arrays (A, C) and at the bottom of the lower sub-arrays (B, D). A third rectangular set 48 forms the remainder of eac sub-array. The indicia in the sets 44 are equivalent to the indicia of the graduated scale 22 on float 20; The indicia 46 are equivalent to volumes of liquid under test and the indicia of the sets 48 indicate the volume of liquid under test which must be replaced with anti-freeze to bring the concentration of anti-freeze in that liquid to the desired level determined by the particular sub-array. In use, e.g. when determining the volume of anti-freeze to be added to a liquid coolant system of a motor vehicle, a user first decides what concentration of anti-freeze - is required. Assuming that the -desired concentration is 30% the user places the cursor on the body 10 with the lugs 34 and 40 uppermost, that is to say nearer the bulb 18. The user then squeezes the bulb 18, places the nozzle 14 in the liquid coolant and then releases the bulb to draw liquid into the body 10. After the hydrometer has been righted and the float allowed to settle the actual concentration of anti-freeze in the sample may be read from the graduated scale 22 of the float 20. The user then move ' s the cursor 30 across the indicia to bring the end of arrow headed lug 34 into register with the figure in set 44 of sub-array A corresponding to that read from the scale 22. The user then rotates the ring member 36 until the arrow shaped lug 40 points towards the figure in the set 46 of the sub-array A corresponding to the total capacity of the coolant system. At this point aperture 42 frames the indicia in the set 48 of sub-array A indicating the volume of liquid which must be replaced with anti-freeze to bring the concentration of anti-freeze in the coolant system to that desired - in this case 30%. If the user had wanted to achieve a final concentration of 40% he could have followed the procedure noted above making use of the sub-array C. If the final desired concentration were to be 35% or 50% the user would initially position the cursor with the lugs 34 and 40 spaced from the bulb end of the body 10 (i.e. nearer the nozzle 14) an hen use sub-arrays B or D as required bringing the end y of lug 34 into register with the appropriate figure in the set 44. Figure 4 shows an alternative form of cursor having advantage in certain situations and in which the ring member 36 is mounted on the ring 32 and held thereon by cooperating grooves 50 as shown. This alternative form of cursor also provides that the ring members 32 and 36 are slotted (i.e. incomplete) to permit their ready assembly one on the other and on the body of the hydrometer with this alternative form the rings are, whilst on the body 10, firmly linked together. Although the tube and float are described above as being of glass it will be appreciated that these two parts of the hydrometer may be made of any suitable alternative material - e.g. a plastics material. It will be seen from the drawings that the part of the tube 10 carrying the sleeve 28 is narrower than the upper part of the tube. This arrangement, which allows the hydrometer to be of substantially constant diameter along its length is though desirable not essential to the invention. Again, the described arrangement enables indicia of maximum size to be printed on the sleeve - such that they are readily read even when the hydrometer is soiled - by providing that the cursor overlies, in use, those sub-arrays of indicia not being used (and that the cursor be removed, reversed and replaced if a different sub-array of indicia is to be used). If it is thought necessary o ' r desirable the sub-arrays may be made somewhat smaller and the cursor held captive on the tube. INDUSTRIAL APPLICABILITY The invention thus provides a hydrometer which facilitates the testing and correction or alteration of the concentration of an additive in a liquid. It will be appreciated that various other modifications may be made to the described arrangement without departing from the scope of the invention. For example the sleeve 28 may be omitted and the indicia formed (e.g. etched) directly onto the wall of the tube. The indicia may provide more or less sub-arrays allowing the hydrometer to be used to determine a range of different final concentrations. The sleeve (if provided) may be readily replaceable with other sleeves giving different ranges of figures. Finally it will be appreciated that the use of the described hydrometers is not limited to that described. For example, it is envisaged that the described hydrometer could be used (with other indicia) to enable determination of the volume of sugar to be added in a brewing operation to achieve a desired alcohol concentration in the final product.

Claims: CLAIMS 1. A hydrometer of the kind comprising a transparent elongate chamber (10) in which a float (20) is located and to which a sample of liquid to be tested is brought in order that a characteristic of the liquid may be ascertained by noting the level of the float within the liquid, characterised by the provision of a calculator in the Jorm of an area of coded information (A,B,C,D) viewable on a wall of the chamber (10) and a cursor (30) movable axially and circumferentially of the chamber across the viewed area of coded information to enable conversion of data read from the float (20) within the chamber (10) to another form. 2. A hydrometer as claimed in claim 1, characterised in that the area of coded information .(A,B,C,D) is an ' array of indicia relevant to a characteristic of a liquid to be tested with the hydrometer. 3. A hydrometer as claimed in claim 1 , characterised in that the information is printed on a plastics material sleeve (28) carried on a wall of the chamber (10). 4. A hydrometer as claimed in claim 2, characterised in that the indicia indicate; the concentration of an additive in the liquid under test, selected volumes of the liquid and volumes of said additive to be added to the liquid to bring its concentration therein to a desired level. 5. A hydrometer as claimed in claim 4, characterised in that the indicia are disposed in a plurality of sub-arrays (A,B,C,D) each of which relates to a different desired final concentration of the additive in the liquid under test. 6. A hydrometer as claimed in claim 4, characterised in that the indicia or each sub-array thereof comprises a first set of indicia equivalent to indicia provided on the float (20) within the chamber (10), a second set of indicia indicating different volumes of the liquid under test and a third set of indicia enabling determination of amount of additive to be added to the liquid to bring its concentration therein to a desired level. 7. A hydrometer as claimed in claim 6, characterised in that said first and second sets of indicia are linear sets running along adjacent edges of the third set which is rectangular. 8. A hydrometer as claimed in claim 7 ' , characterised in that the cursor (30) is in the form of a first ring member (32) movable axially and circumferentially of the chamber to bring a part (34) thereof into juxtaposition with one of said first set of indicia, a second ring member (36) carried on the first ring member (32) and movable thereon circumferentially of the chamber to bring a part (40) thereof into a predetermined relationship with one of said second set of indicia such that an indicator (42) of the second ring member then identifies one of said third set of indicia. 9. A hydrometer as claimed in claim 8, wherein said parts (34,40) of the first and second ring members are lugs formed on the edges of those members (32,36) and wherein said indicator (42) of the second ring member comprises an aperture formed in the lug (40) comprising the said part of that member. 10. A method of determining the volume of an additive to be added to a liquid to bring the concentration of the additive in the liquid to a desired level which makes use of a hydrometer as claimed in any one of the preceding claims.

Inventors: POULTEN JOHN HENRY, POULTEN, JOHN, HENRY
Applicants: POULTEN LTD JOHN, JOHN POULTEN LIMITED
Application year: 1985
Main classification: G01N9
IPC codes: G01N9