By Wang Xiangming
A water meter is a type of measurement instrument with a calculator to continuously determine the volume of water passing through the device, and generally these fall into three categories: simple mechanical water meters, mechanical water meters with an electronic communication device, and fully electronic water meters.
With nearly 20 years of development, the measurement accuracy and flow features of mechanical water meters are constantly improving. There are various types of mechanical meters, such as the single jet type, multi jet type, Woltmann type, volumetric type, etc., all of which have become widely used in the water meter market and will continue to meet market demand for the foreseeable future.
The advantages of the mechanical meter lie in its simple structure and reliable operation while the obvious disadvantages are the narrow measurement range and reduced accuracy at low flow rates. Moreover, being mechanical the errors change over a long period of operation. This type of meter is only suitable for use when the pipe is sealed and full of water, and it also demands a higher standard of water quality, but it does not measure well or even cannot measure multi-types of flows. The meter also has simple functions and can only calculate and display the cumulative flow. Thus, it needs manual data collection and payment settlement, and is unable to meet the modern information needs.
Mechanical water meters with electronic communication have come into market within the last 20 years. With the mechanical meter as the basis, and by adding various types of electronic signal sensors, this type of meter can now meet the normal informational and management requirements. Currently they are a substitute for the simple mechanical meters, but as the basis is still mechanical, there is no change in the measurement aspect. Further, with the addition of the electronic components these not only require protection but also increase the possibility of product instability. For most of this type of meter, the electronic readings and mechanical readings coexist, with the possibility of an inconsistency between the two readings giving rise to settlement issues. Therefore, backwardness in technology development determines that this is still a transitional product.
The electronic water meter is a type of instrument which is based on various new measurement principles, and is completely electronic. These measurement principles include fluidic measurement, electromagnetic measurement, and ultrasonic measurement, among others.
The fluidic method is a way to deduce the fluid volume by making use of the Coandå effect, in which an oscillation frequency in proportion to the fluid velocity is established in a fluid path with a specific structure. Meters with this measurement principle have the advantage of a broad measurement range and high accuracy at low flow rates, with no possibility of also measuring air. In addition the device is completely electronic and has a remote communication capability.
The electromagnetic method is a way to deduce the fluid volume by making use of the induced electromotive force produced by the fluid flowing through a magnetic field, which is in proportion to the fluid velocity.
Generally, compared with mechanical water meters, the measurement accuracy of electronic meters is much higher, which make it easier to realise the desired informational requirements and to provide better methods for networking and automation.
With the development of electronic technology, electronic water meters mainly powered by batteries will also become more mature, and will surely become part of daily life with the push of the global professional utility meter manufacturers. It can be foreseen that in the next 10 to 20 years, or even within a shorter time, fully electronic water meters will replace the mechanical water meters and those mechanical water meters with electronic communication.
The energy meter field has realised full electronisation and is coming to the phase of the “intelligent electricity network.” In this way, information collection and the control of electricity use data can be realised. Further, effective data for second time use can be provided, in order to finally realise the reasonable allocation and use of electricity and to help ease the energy crisis. We believe that in the future, the water meter field will be similarly electronicised and that the “intelligent water network” will come into being, providing an important tool for water resource settlement and to ease the water resource crisis.