GB2215464A

GB2215464A - Liquid level sight glass

Info

Publication number: GB2215464A
Application number: GB8805649A
Authority: GB
Inventors: R A O Ziko
Original assignee: Ziko Dr A O
Current assignee: Ziko Dr A O
Priority date: 1988-03-10
Filing date: 1988-03-10
Publication date: 1989-09-20
Anticipated expiration: 2008-03-10
Also published as: GB2215464B; GB8805649D0

Abstract

A liquid level indicator comprises a sight tube 4 and a bar chart 6 carrying vertical lines 8 located behind the tube. When the tube 4 is full of liquid, the tube acts as a magnifying lens and the apparent spacing of the vertical lines 8 is substantially increased. The actual liquid level is clearly distinguished as the junction of the differently spaced vertical lines when the lines are observed through the tube 4. The tube is mounted in a filler block of an anaesthetic vapouriser. <IMAGE>

Description

IMPROVED LIQUID LEVEL INDICATOR The present invention relates to liquid level indicators and in particular to liquid level indicators for anaesthetic vaporisers.

Throughout this specification the term "anaesthetic" is intended to embrace anaesthetic and analgesic agents.

As explained in UK Patent No. 1193241 anaesthetic vaporisers are used with anaesthesia machineS for mixing the vapour of a volatile liquid anaesthetic with a carrier gas such as air, oxygen, nitrous oxide or a combination thereof.

Usually an anaesthetic vaporiser is dedicated for use with only one type of anaesthetic and UK Patent No. 1193241 and UK Published Patent Application No. 2189472 each describe a filling system which substantially eliminates the possibility of an anaesthetic vaporiser being filled with the wrong anaesthetic vapour.

In order for an anaesthetist to know the amount or level or liquid anaesthetic in the sump of an anaesthetic vaporiser it is known to provide a liquid level or sight tube in the filler block of the vaporiser. The anaesthetist has to check the level of liquid anaesthetic appearing in the liquid level tube by looking for the meniscus of the liquid which is invariably transparent. It is known for the anaesthetist to have to shake the vaporiser to see the meniscus moving to verify its level in the liquid level tube.

It is an aim of the present invention to provide a liquid level indicator which allows the level of the liquid to be seen easily by an observer.

According to one aspect of the present invention, a liquid level indicator comprises a transparent tube for containing liquid the level of which is to be indicated and a member carrying spaced vertical lines said member being spaced from the tube, the arrangement being such that when the tube contains liquid, the tube acts as a magnifying lens so that the apparent spacing between adjacent vertical lines is increased when the lines are observed through the tube.

According to a further aspect of the present invention, an anaesthetic vaporiser comprises a liquid level tube for containing liquid anaesthetic the level of which is to be indicated and a member carrying spaced vertical lines said member being spaced from the tube, the arrangement being such that when the tube contains liquid, the tube acts as a magnifying lens so that the apparent spacing between adjacent vertical lines is increased when the lines are observed through the tube.

An embodiment of the invention will now be described, by way of example, reference being made to the Figures of the accompanying diagrammatic drawings which: Figure 1 is a perspective view of three anaesthetic vaporisers the middle one of which is being filled with liquid anaesthetic vapour via a filler block; Figure 2 is a perspective view of the filler block of Figure 1; Figure 3 is a horizontal cross section through a part of the filler block of Figure 2; and Figure 4 is a detail of the filler block of Figure 2 showing a view through a liquid level tube when said tube contains an anaesthetic liquid.

As shown three anaesthetic vaporisers 1 are releasably attached to the back bar (not shown) of an anaesthesia machine in a manner known in the art. Each vaporiser 1 has mounted thereon a filler block 2 which includes a transparent liquid level or sight tube 4 located at one corner of the filler block 2.

Behind the liquid level tube 4 and spaced therefrom is a member in the form of a bar chart 6 which has marked thereon spaced vertical bars or lines 8.

When the tube 4 is empty of liquid anaesthetic the individual lines 8 are clearly seen through the transparent tube at substantially their normal spacing. However, when the tube 4 is full of liquid the tube 4 acts as a magnifying lens and the apparent spacing of the lines is substantially increased.

When the tube 4 is partially filled with liquid anaesthetic then the actual liquid level is distinguished as the junction of the differently spaced lines (See line A-A in Figure 4).

It has been found that the junction of the apparently differently spaced lines is far easier to observe than the level of the meniscus of the liquid. This effect is much more easily seen from a distance.

In a modification, minimum and maximum lines may be marked horizontally on the bar chart 6 to indicated permitted minimum and maximum levels of anaesthetic liquid to be placed in the vaporiser.

The e longitudinal lines are preferably the same thickness as the vertical lines.

The e lines, both vertical and horizontal, may be colour coded to indicate the liquid anaesthetic agent contained within the vaporiser.

Furthermore, the lines may be made luminous so that they are visible in the dark. This is an advantage when certain eye operations are being performed.

The advantage of the embodiment described above is that rather than look for a very unclear meniscus to check the level of liquid anaesthetic in a vaporiser the anaesthetist now need only observe the junction of the apparently differently spaced lines. In practice, this makes the level of the liquid anaesthetic in a vaporiser very easy to observe. This is an important advantage particularly in an operating theatre when an anaesthetist may be required to monitor readings on a variety of different instruments.

Although reference has been made in the above described embodiment to a liquid level indicator for an anaesthetic vaporiser clearly the liquid level indicator could be incorporated into other devices where the level of a liquid needed to be indicated.

Claims

1. A liquid level indicator comprising a transparent tube for containing liquid the level of which is to be indicated and a member carrying spaced vertical lines, said member being spaced from the tube, the arrangement being such that when the tube contains liquid, the tube acts as a magnifying lens so that the apparent spacing between adjacent vertical lines is increased when the lines are observed through the tube.

2. An anaesthetic vaporiser comprising a liquid level tube for containing liquid anaesthetic the level of which is to be indicated and a member carrying spaced vertical lines, said member being spaced from the tube, the arrangement being such that when the tube contains liquid anaesthetic, the tube acts as a magnifying lens so that the apparent spacing between adjacent vertical lines is increased when the lines are observed through the tube.

3. An anaesthetic vaporiser as claimed in claim 2, in which the liquid level tube is mounted in a filler block at a corner of the filler block.

4. An anaesthetic vaporiser as claimed in claim 2 or 3, in which the member is in the form of a bar chart and includes horizontal lines indicating minimum and maximum positions for the level of the anaesthetic liquid.

5. A liquid level indicator constructed and arranged substantially as hereinbefore described with reference to and as illustrated in the Figures of the accompanying drawings.

6. An anaesthetic vaporiser constructed and arranged substantially as hereinbefore described with reference to and as illustrated in the Figures of the accompanying drawings.