GB2546272A

GB2546272A - A system comprising a transportable gas supply cylinder for pressurised gas and a method of monitoring such a cylinder

Info

Publication number: GB2546272A
Application number: GB1600568.8A
Authority: GB
Inventors: Bayerl WILHELM
Original assignee: Linde GmbH
Current assignee: Linde GmbH
Priority date: 2016-01-12
Filing date: 2016-01-12
Publication date: 2017-07-19
Also published as: GB201600568D0

Abstract

A transportable gas supply cylinder system has a sensor to measure the temperature of the cylinder contents, and an indicator to indicate an abnormal temperature condition. If the temperature condition is higher than a predetermined temperature and threshold then an abnormal temperature condition is indicated. The sensor may be thermochromatic material on the outer wall of the cylinder with a colour change providing the indication.

Description

A System Comprising a Transportable Gas Supply Cylinder for Pressurised Gas and a Method of Monitoring such a Cylinder

The present invention relates to a transportable gas supply cylinder for pressurised gas.

Such cylinders are known in a wide range of medical, industrial and domestic applications to deliver “bottled gas” which is usually brought to the site on a vehicle. Used cylinders are then taken away for refilling. Typical applications for these type of cylinders are: Acetylene and Oxygen for welding, shielding gases, modified atmosphere gases for food packaging.

Such gases tend to be stored in a wide variety of environments which may be subject to wide temperature fluctuations. There is no constant control of the gas cylinder temperature. However, an overheated cylinder (typically one at greater than 65-80 eC) can become an immediate safety risk in that it is liable to leak or explode. Alternatively, it can be irreversibly weakened thereby storing up problems for the future. Acetylene cylinders, in particular, can explode if they are overheated by external sources such as fire, welding torches or incorrect storage, or by flash-back. An overheated acetylene cylinder is a serious problem if the cylinder is not cooled down immediately.

In another example aluminium alloy cylinders are sometimes heated up by customers with electrical heating belts in order to increase the vaporisation speed of liquefied gases. If the temperature is too high, the material strength of the aluminium alloy is dramatically reduced and can lead to cylinder rupture during the next fillings of the cylinder.

According to a first aspect of the present invention there is provided a system comprising a transportable gas supply cylinder for pressurised gas, a sensor to measure the temperature of the cylinder contents, and an indicator to indicate an abnormal temperature condition if the temperature condition is higher than a predetermined temperature and threshold.

The provision of a sensor allows the temperature of the cylinder contents to be monitored over a period of time and the indicator can be used to determine if there has been a temperature increase which is likely to be unsafe.

The sensor may be a thermochromatic material on the outer wall of the cylinder with a colour change providing the indication. This provides a simple way of obtaining an indication of an abnormal temperature condition. This is an indirect way of sensing the temperature of the contents as it senses the temperature of the contents via the cylinder wall. This can simply be painted onto the cylinder wall or may be on a label which his adhered to the cylinder wall. Such a sensor does not require a separate power source.

The thermochromatic material may be configured to undergo an irreversible temperature change. This will provide an indication to a user or the supplier that, at some period, there has been an unsafe change in temperature. Alternatively or additionally the thermochromatic material may be configured to undergo a reversible change such that it provides an indication to the user only at the point that the temperature condition is now abnormal.

Irreversible and reversible thermochromatic materials may be used in combination to provide an indication of both present and past temperature changes.

There may be more than one thermochromatic material used, these different materials being arranged to change colour at different temperatures which provides some indication of the severity of the temperature change.

As an alternative to or in addition to the sensor being a thermochromatic material, it may be an electrical sensor as this is more versatile than the thermochromatic material. With an electrical sensor, the indicator may be attached to the cylinder or may be remote from the cylinder and the cylinder further comprises transmission means to transmit the signal indicative of cylinder temperature to the indicator. Such an arrangement is useful, for example, where the sensors are in communication with a separate workstation allowing a user to monitor the temperature of numerous cylinders simultaneously. Alternatively, it may be linked to a portable device such as a smart phone or tablet or to some wearable device all of which are good ways to generate an alert to a user if the temperature condition is outside a predetermined temperature.

The temperature condition may be such that the abnormal temperature condition will be reached if a predetermined temperature is exceeded only on one occasion and for a short time. Alternatively the abnormal temperature condition requires a predetermined temperature to be exceeded for a predetermined number of times. This will alert a user to the fact that a cylinder has been repeatedly overheated. Alternatively or additionally the abnormal temperature condition is that a predetermined temperature has been exceeded for a predetermined time. This will allow a user to be alerted if the cylinder is at a high temperature for a relatively long period.

Any combination of the above may be used. For example, the user may be alerted to the fact that the temperature of the cylinder has exceeded a relatively high threshold on a single occasion or to the fact that it has exceeded a lower threshold but for a relatively long time or on a large number of occasions.

According to a second aspect of the present invention there is provided a method of monitoring a transportable pressurised gas supply cylinder, the method comprising measuring the temperature of the cylinder an alerting a user to an abnormal temperature condition.

The method may be used in combination with any one of the preferred features of the apparatus referred to above.

An example of a system and method in accordance with the present invention will now be described with reference to the accompanying drawings, in which:

Fig. 1A is a schematic cross-section of a cylinder with an electrical sensor in a non-critical condition;

Fig. 1B is a similar view in the process of undergoing a dangerous overheating;

Fig. 1C is a similar view after it has undergone dangerous overheating;

Fig. 2A is a cylinder with thermochromatic label in a non-critical condition;

Fig. 2B is a similar view in the process of undergoing a dangerous overheating; and Fig. 2C is a similar view after it has undergone the dangerous overheating.

The cylinder 1 is generally well-known in the art and will not be described here. Suffice it to say that it is a pressure containing vessel with a wall 2 and a valve system 3 via which the cylinder can be refilled and emptied.

The improvement provided by the present invention is the addition of a temperature sensor as shown in Figs. 1A to 1C which may either be an electrical sensor 3A positioned inside the cylinder or an electrical sensor 3B positioned outside the cylinder to provide an indirect measurement. The cylinder may be connected to a controller 4 which is integral with the cylinder. This may provide an alert in the form of a light and/or sound from the cylinder itself. Alternatively, the sensor 3A, 3B may be connected to a wireless transmitter 5 which transmits signals to a remote location such as a control centre or remote device to alert a user to a dangerous overheating condition. Suitable sensors for this purpose include thermistors, thermocouples, resistance thermometers and silicon bandgap temperature sensors.

Alternatively, a thermochromatic sensor 10 may be placed on the external wall of the cylinder as shown in Figs. 2A-C. This may either be painted or may be a label which is adhered to the outer wall of the cylinder. It is preferably placed in several locations on the cylinder for greater visibility.

Figs. 2A-C show the manner in which the thermochromatic sensor operates. This particular sensor is a combination of reversible and irreversible thermochromatic material. Fig. 2A shows the sensor before dangerous overheating has occurred which is a single plane colour. Fig. 2B shows the sensor which has been overheated to an unsafe temperature, in this case over 80SC. The overheating has caused the thermochromatic materials to reveal the words Overheated” and “Danger”. This will alert a user to the fact that the cylinder has become dangerously hot.

The thermochromatic change which indicated by the word “Danger” (Fig. 2B) is a reversible thermochromatic change. Thus, a user can take preventative measures to cool the cylinder down and will become aware when this has happened by the disappearance of the word “Danger”. The word Overheated” (Fig. 2C) has been displayed due to an irreversible change. Thus, when the cylinder is sent for refilling, the person doing the refill is aware that it has been subject to a potentially dangerous temperature overload and can carry out further safety checks on the cylinder and discard it if necessary.

Reversible and irreversible thermochromatic sensors suitable for this use are available from different suppliers ( e.g. Brady Corporation, etifix GmbFI, bsb-bentlage GmbFI).

Claims

CLAIMS:

1. A system comprising a transportable gas supply cylinder for pressurised gas, a sensor to measure the temperature of the cylinder contents, and an indicator to indicate an abnormal temperature condition if the temperature condition is higher than a predetermined temperature and threshold.

2. A system according to claim 1, wherein the sensor is a thermochromatic material on the outer wall of the cylinder with a colour change providing the indication.

3. A system according to claim 1 and claim 2, wherein the thermochromatic material is configured to undergo an irreversible temperature change.

4. A system according to claim any one of the preceding claims, wherein the thermochromatic material is configured to undergo a reversible change.

5. A system according to any one of the preceding claims, wherein the sensor is an electrical sensor.

6. A system according to claim 5, wherein the indicator is remote from the cylinder and the cylinder further comprises transmission means to transmit the signal indicative of cylinder temperature to the indicator.

7. A system according to any one of the preceding claims, wherein the abnormal temperature condition will be reached if a predetermined temperature is exceeded only on one occasion and for a short time.

8. A system according to any one of the preceding claims, wherein the abnormal temperature condition requires a predetermined temperature to be exceeded for a predetermined number of times.

9. A system according to any one of the preceding claims, wherein the abnormal temperature condition is that a predetermined temperature has been exceeded for a predetermined time.

10. A method of monitoring a free-standing transportable pressurised gas cylinder, the method comprising measuring the temperature of the cylinder an alerting a user to an abnormal temperature condition.

11. A method of claim 10 carried out on the system of any one of claims 1 to 9.