Invention Background

 Prepaid gas meters have been produced in our country for the past 10 years. During this time, manufactures have gone through many changes with the first ones in the field going bankrupt and their products discontinued. There has not been a big market up until now, however with the development of this type of meter, the situation will change.

Experience has shown that it has been difficult gain widespread acceptance of traditional battery powered prepaid gas meters in the government market. The reason for this is very simple, one reason is it violates the price law, and another, it is very easy to steal heat from the heat meter. Many manufactures promote their products vigorously in the traditional Chinese manner, but, because they can't satisfy their customers' requirements, they can't establish the popularity of the products and have wide spread application within a city. There is still a large gap between existing prepaid gas meters and the ideal

Many years of experience have shown that in moist environment ,it is very difficult to keep battery operated gas meters working continuously. It is not absolutely impossible however it can only be achieved by increasing the cost. Increasing the cost makes it difficult improve its popularity. The basic gas meters cost less than RMB 120, but the prepaid gas meter will cost hundreds of Yuan. The value of this increased investment must be matched by improved functionality. Some users will not care about the high price, but if high-cost prepaid gas meters are unreliable, gas supply company will not accept them.

Battery performance is crucial as it will be required to supply the prepayment gas meter with power for a long period. If the battery is influenced by external temperature or humidity then the performance of the complete product and its lifespan will be affected.

When batteries run out the situation can be unplanned and unexpected. This affects people’s daily life and causes disruptions to supply. If the batteries could be timed to all run out at the same time they could be replaced after set periods of operation, however because of differences in the performance of batteries and unpredictable power demand they cannot be expected to run out at the same time.

Dismantling meters and changing batteries creates endless problems for whoever is responsible for them. Monitoring the state of the battery requires electronic circuitry which consumes energy and the effectiveness of this will also influence the reliability of the whole product.

When system control circuit is working, it must be powered and the IC card interface should be open. Once interrupted by the external high pressure, system will paralyse. Therefore, it will cause the failure of measurements and the control of the prepaid gas supply.

Using the circuit to monitor the meter flowrate and to obtain measuring data, requires an electric sensor with good performance. Moreover, enabling the system to switch the pipeline off effectively needs a control valve system.

To satisfy the requirements described above will require the meters to be fitted with high price battery, battery monitoring circuit, good performance sensor, reliable valve control system and a complicated electronic display. These greatly raise the cost of the product making the popularity and wide spread application of prepaid gas meters increasingly difficult to establish.

If we want to solve the problems associated with prepayment meters described above we need to develop a new approach to traditional measuring and control technology.

After more than two years of research and development on the basic of combining the facility of the ‘IC card prepaid gas meter’ and security of the ‘code-type prepaid gas meter’, we have developed a control function for a prepaid gas meter which does not need working power.