Measuring and testing – With fluid pressure – Leakage
Reexamination Certificate
1999-11-05
2001-11-06
Larkin, Daniel S. (Department: 2856)
Measuring and testing
With fluid pressure
Leakage
C073S04050R, C073S049200, C137S313000, C222S051000, C222S067000, C222S108000, C141S086000, C141S088000, C141S31100A
Reexamination Certificate
active
06311547
ABSTRACT:
FIELD OF INVENTION
The present invention relates to a sensor for detecting leaks in a dispenser for liquid hydrocarbons.
The invention can be applied to particular advantage in the field of environmental protection against hydrocarbons, especially fuels for motor vehicles.
BACKGROUND OF THE INVENTION
In view of growing concerns to preserve the quality of the environment, it appears essential to fit liquid hydrocarbon dispensers with a sensor for detecting leaks, regardless of where they originate within the dispenser.
Several detection systems have been proposed for this purpose.
Firstly, it is possible to detect the vapours from liquid hydrocarbons inside the dispenser. This can be achieved either by means of biological, optical or combined sensors or by measuring the density of vapours contained in the dispenser. However, in view of the very marked variety of temperatures, humidity and quality of installation at service stations, this type of detection triggers numerous false alarms or, even worse, no alarm at all. Biological sensors, furthermore, have a tendency to become poisoned by additives. When it comes to liquid hydrocarbons of the gas oil type, these generate no or little vapour and it is difficult to detect their presence other than by the odours of the additives which they contain.
It would be conceivable to detect leaks by taking pressure measurements at different points in the pipework system for the hydrocarbons. However, to detect slight leaks, it is necessary to have a perfect knowledge and model of the distribution of pressure in the passages depending on the conditions under which the dispensers are installed on site and the sensors need to be extremely sensitive, in order of several mbars, and be capable of withstanding pressure surges of more than 15 bars, which require extremely expensive equipment. Moreover, the software must exhibit a high degree of intelligence to be able to process data from the sensors. Finally, sensors operating in hazardous areas also need to be security-protected and are therefore very expensive.
SUMMARY OF THE INVENTION
Accordingly, the technical problem to be resolved for the purposes of the invention is that of proposing a sensor for detecting leaks in a liquid hydrocarbon dispenser that would be simple in design and cost-effective whilst providing perfect efficiency and the requisite security.
This technical problem is resolved for the purposes of the invention due to the fact that said sensor comprises a sealed plate, arranged on the base of said dispenser and fitted with a catchment container designed to receive the liquid hydrocarbons collected by said sealed plate and coming from leaks in the dispenser, said catchment container having a level detector for said hydrocarbons, capable of halting operation of the dispenser if the detected level of hydrocarbons reaches a given level.
This provides a perfectly reliable sensor due to the presence of the sealed plate in the base of the dispenser where liquid hydrocarbons emanating from all leaks, regardless of their origin, are collected and detected. Furthermore, the sensor proposed by the invention uses components (plate, catchment container and level detector) which are cheap and easy to install in the dispensers.
By virtue of another advantageous feature of the leakage sensor proposed by the invention, said dispenser has a pump, a flow-rate counter and a computer, said computer being capable of detecting a flow rate of liquid hydrocarbons in said counter after the dispensing process because said pump continues to operate for a given period.
As a complement to overall detection of leaks inside the dispenser, this particular feature pinpoints any leaks which might occur downstream of the flow-rate counter. In practice, after dispensing, immediately after the gun is replaced, rather than halting the motor of the pump in the dispenser as usually happens, operation of said motor is continued for a period in the order of a few seconds during which the computer continues to monitor the data from the counter so that if a flow rate is detected by the computer, it can only be attributable to a leakage downstream of the counter, and an indication of this fault can then be given to the service station manager, pinpointing where the dispenser is faulty. This detection system is particularly useful in the case of dispensers fitted with double hose vapour recovery devices as a means of detecting any leaks of liquid hydrocarbons which might be sucked in by the recovery device.
The description outlined below with reference to the appended drawings, given by way of illustration and not restrictive in any respect, should provide an understanding of what the invention comprises and how it can be operated.
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Drinker Biddle & Reath LLP
Larkin Daniel S.
Tokheim Services France
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