Since water and other liquids are used literally everywhere, their metering devices have become necessary in all areas of human life and work – from a hydroelectric power station to a private bathroom. In this article we will try to understand the intricacies of accounting for water for our own needs..
Classification of meters
Water meters perform three critical tasks:
- Removal of data on the flow, its speed and volume.
- Conversion of flow data into mechanical motion, pulse or voltage drop.
- Visualization or transmission of converted data.
Ways to implement these tasks are solved in all possible ways, thanks to modern technologies..
According to the principle of operation (fixing the properties of the flow), there are three types of water meters.
The action is based on the creation of a difference in the values of electromagnetic induction. Water moves in a constant magnetic field and creates an electric current (induction phenomenon). The strength of this current is always directly proportional to the speed of the water flow. Having data in this proportion, the result (volume of passing water) can be obtained through mathematical calculations.
- The viscosity of the medium does not matter.
- No parts subject to wear.
- No contact with water – no flow resistance.
- A weak signal can be drowned out or distorted by stronger magnetic fields such as live wires. Additional signal amplifier required.
- High requirements for liquid quality – no sediment and complete transparency.
The flow rate is measured through the difference in the ultrasound propagation speed in the directions “along the course” and “against the course” of the water flow. The data is captured continuously to a recording device or transmitted for processing. It is an electronic sensor that is attached to the water pipe – this is the whole installation.
- Extremely Accurate – 0.1 L error at close to 0 flow rate.
- Outdoor mounting (fixing).
- All the advantages of an electromagnetic device.
- Sound conductive pipe material required.
- Requires no air in the water.
- Susceptible to distortion from external magnetic fields.
- Does not have a standard visualizer – an additional device for reading data is required.
They take data from sensors directly in the environment. Their installation is associated with a tie-in into the pipe. According to the method of reading data on the flow, they are divided into two types.
Vortex.The force of vortex of the medium flow, which meets a static obstacle, is registered. The sensor, located behind the prism-shaped barrier, transmits a signal to the converter, which displays the readings on a standard electronic display. Instead of a scoreboard, it is allowed to install a transmitting or recording device.
- No mechanical wear on moving parts.
- Completely insensitive to environmental conditions.
Disadvantage: high resistance to flow.
All of the above flow meters have one common drawback, sometimes decisive. Electronics is volatile and constantly requires electricity, that is, an uninterruptible power supply is needed, otherwise a failure may occur. This makes residential installation risky – temporary blackouts are commonplace.
Tachometric.An impeller is located inside the pipe (device branch pipe), which the flow rotates, passing through the pipe. The rotation is transmitted to the meter’s accounting devices and converted into readings. In turn, such devices are divided in size into two types:
- Vane – for pipe diameters up to 30 mm. It is them that we most often see installed in apartments. Fastening method – insert.
- Turbine – for diameters from 40 to 200 mm. The sensor is essentially an enlarged modified impeller. Flange mounted. Used in factories and water supply units.
The tachometer counter has quite understandable disadvantages associated with the mechanical operation of parts:
- Wear and contamination. Poor quality water makes the impeller unusable relatively quickly. Therefore, such meters require regular (every 4-5 years) verification by the Metrological Supervision.
- The operation of the mechanism can be disrupted by a powerful magnet, which often pushes the consumer to violate the law.
- Installation requires stopping the system and tapping into it.
It also has valuable advantages:
- Autonomous non-volatile work.
- Standard scoreboard with measurement results.
- Possibility of installing upgrade devices (impulse tube, radio module).
It was energy independence that served as a decisive factor for the adoption of tachometric meters for wide technical “armament”. Water accounting is carried out around the clock, without regard to power surges or its absence. At the same time, data is accumulated continuously on a standard mechanical display.
Data transfer methods
The increase in the number of metering devices in recent years has led to an increase in the volume of data on their readings that require processing. For this, transmitting devices and concentrators (in fact, servers) have been developed, which receive signals from flow meters and calculate all the necessary values arising from them. This is how the classification of meters by data transfer method appeared.
A modern meter can record and transmit data in three ways:
- Visualization of digital values on the display, which can be electronic (volatile) or analog (independent).
- Impulse tube. This is an additional device that improves the conventional vane meter. The tube has a sealed contact (reed switch) at the base, which converts the rotation of the impeller into an impulse and transmits it for further computational processing, including wireless transmission.
- Radio module. I mean any device for wireless data transmission – radio beacon, internet modem, GPS beacon. Thanks to such a system, an individual centralized system for collecting water consumption data can be installed – at the entrance or at the house..
A noteworthy fact is that the described devices are both standard and optional. That is, they can be used to modernize primitive models. And here again simple mechanical vane counters win. They are inexpensive – 12-17 USD. That is, they do not require electricity, show the result on an integral display and allow you to install, if necessary, the devices described above.
Simply put, the task of a meter is to create movement or vibrations of any kind – mechanical, ultrasonic or electromagnetic – and receive a signal from them. This signal is subsequently recorded and processed – this is how we receive data about the flow and call them “meter readings”.
Table. Comparative characteristics of water meter models
Model Manufacturer A type Water type Add. equipment Price, cu e. Zenner Minomess etw-n qn1.5 Germany Vane Hot Calibration drum + 4 precision dials 23 SGV-15 “Betar” Tatarstan Vane Hot Calibration drum 13.5 Meter (SHV-20) Russia Vane Cold Calibration drum + reed switch mounting option 15.5 Zenner ETK-N-AM Germany Vane Cold Calibration drum + impulse tube (standard) 20 “Meter” DU-32 Russia Vane Universal Calibration drum 45 Prompribor “MasterFlow” 50 mm Russia Electromagnet Universal Transmitting device 230 AC Electronics US-800 Russia Ultrasound Universal Electronic scoreboard with transmitting device 280 MULTICAL 62 Denmark Ultrasound Cold Electronic scoreboard 120
Another invisible, at first glance, nuance speaks in favor of simple vane models. To take readings, the personal presence of a person is required – along the way, the condition of the meter, pipes, connections, premises is examined. This provides additional insurance against accidents – a potential leak or breakthrough can be identified along the way..
Whichever expensive meter you choose, its payback is only a matter of time. Even the most “advanced” models with the maximum configuration and the price of 120 USD. e. pay off in 4-6 years (with a service life of up to 20 years).