BACKGROUNDART A conventional tot measuring device includes a thimble of predetermined volume (for example 25 ml which corresponds to a typical tot measure for liquors). The thimble includes an inlet for the liquor from a container and an outlet therefrom, both of which are controlled by suitable valve means. These valve means may be operated by electromagnetic, electro-optical or mechanical means. In the latter case the thimble may be moved from a first position in which it is full, to a second limiting position in which the full contents of the thimble are discharged. This movement may be actuated by the rim of a drinking tumbler so that the tot enters the tumbler ready for dilution with water or mixer.

The thimble then moves to its first position, during which it is refilled with liquor for the next discharge..

As there is a tight fit between the inlet of the thimble and the container, the liquor will only fill the thimble if the air therein is released above the level of the liquor in the container : An air vent has been used for this purpose which extends outside of the container to a position above the level of liquor therein. The level of liquor in the air vent corresponds with the level of the liquor in the container so that when the thimble is discharged, the volume of liquor in the air vent is drawn into the outward flow, thus resulting in a total volume of tot in excess of the predetermined volume. As the level of the liquor in the container drops so does the level of liquor in the air vent with the result that the actual volume of the tot discharged becomes smaller as the content of the container decreases. This may be a problem in some establishments and is also, in some countries, against the law as the total tot volume may be in excess of a preordained volume.

It is an object of the present invention to provide for the discharge of equal tot volumes whatever is the level of liquor in the container. The invention also extends to other liquids such as juices and beverages.

DISCLOSURE OF THE INVENTION According to the invention a liquid tot dispensing device includes a container for the liquid and a thimble of predetermined volume, the thimble having an inlet from the container and an outlet, both being valve controlled; the interior of the thimble having a vent leading to the atmosphere, and the container having a second vent leading from a low level in the container to the atmosphere, the location of the lower end of the second vent being determined in accordance with the desired height of the level of liquid in the first vent.

It is important that the container is airtight.

In operation, starting with a full thimble, the liquid is dispensed into a suitable vessel and air is drawn from atmosphere into the thimble through the first vent. The liquid is then caused to fill the thimble, thus displacing the air and causing a partial vacuum in the space in the container above the level of the liquid. This vacuum causes air to be drawn through the second vent from atmosphere, and this air bubbles through the liquid into the space, thereby restoring the pressure in the space.

The level of liquid in the first vent will be at the same level as the bottom end of the second vent. This will ensure that all tots will be of the same volume.

The thimble may be actuated by any of the means known in the art and as described above and below.

In the event that the ambient temperature may rise, for example after hours when the air-conditioning is off, the pressure in the space may rise to such an extent that liquid is forced through the second vent causing a mess and wastage. This may be avoided by the provision of a relief valve.

Such a relief valve may include a flexible membrane located in the filler cap. This membrane is clamped in the filler cap and has one or more orifices. A second membrane lies on the first membrane and seals the orifices in the normal state of pressure in the container. The bottom of the filler cap includes one or more openings in communication with the interior of the container. The filler cap is thus in a sealed condition. However, if the temperature, and therefore the pressure of the air in the space above the level of the liquid rises, air is caused to enter the openings and to bear against the lower side of the first membrane, which, in turn, causes the second membrane to lift from its seat so that the air can flow through the orifice/s in the first membrane to atmosphere.

BRIEF DESCRIPTION OF THE DRA WINGS An embodiment of the invention is described below with reference to the accompanying drawings, in which: Figure 1 is a sectional front view of a tot dispenser according to the invention; Figure 2 is an end view thereof ; and Figures 3 and 4 are sectional side views of a filler cap incorporating a relief valve.

BEST MODE FOR CARRYING OUT THE INVENTION In Figure 1 a container 10 for liquor connects with thimble 12 through orifice 14 which is controlled by a suitable valve 15. The thimble has an outlet 16.

An air vent 20 connects the interior of the thimble to atmosphere. A second vent 22 extends from a low level in the container to the atmosphere.

The pressure in the thimble after discharge will be atmospheric and this air is forced up vent 20 as the thimble is refilled with liquid. At the same time the flow of liquor in the thimble causes a partial vacuum to be formed in the space 24 above the level of the liquor in the container. The partial vacuum, causes air to be drawn into vent 22, and this air bubbles up through the liquor into the space 24. The pressure in the space 24 is atmospheric pressure less the pressure due to the head of liquor above the lower end of the. vent 22. This ensures that the level of liquor in the vent 20 corresponds with the end of the vent 22 at each discharge and refilling operation.

A filler cap 26 is provided which also serves as a relief valve in circumstances when the pressure in the space above the level of the liquor increases due to an increase in temperature-as may happen after closing hours when the air-conditioning is no longer operating.

This filler cap is illustrated in detail in Figures 3 and 4.

In Figure 3, the bottom 30 of the filler cap has openings 32 which communicate with the interior of the space 24.

A membrane 34 is clamped together with membrane 36 between the periphery of a cylindrical element 38 and a shoulder 40 of the filler cap. The membrane 34 has an orifice 42 and this is closed by the membrane 36 under normal conditions of pressure in the space 24. The membrane rests on a plinth 44 which has a post 46 receiving the central orifices 48 and 50 of the membranes. The filler cap thus seals the space. However, if the pressure in the space rises, the situation in Figure 4 may be reached with the air flowing through openings 32 to cause membrane 34 to expand and to cause membrane 36 to dome sufficiently for the air to move through the orifice 42, through the central orifice 50 of membrane 36 and thence to atmosphere via hole 52 in the cylindrical element 38.

A vent protection cap 28 is also provided.

The thimble comprises a spindle 60 which is actuatable by a solenoid 62 between a first position in which the lower end 64 of the spindle seals the discharge opening 16 and a second position in which the spindle moves into a position in which the other end 68 seals against the opening 14 between the container and the thimble. A compression spring 70 is located on the spindle.

The end 74 may include a spiral passage to prevent the possibility of persons opening the thimble by inserting a pin or the like upwards through the discharge opening 16.